Case Essay Example | Topics and Well Written Essays - 500 words - 9

Case - Essay Example Moore Tires offered Jonathan, who was an employee and owner of Morecedes Tires an employment opportunity that he agreed to. While conducting his routine responsibilities within the new job, the claimant was an employee of Moore Tires and not Morecedes tires, where he had previously worked. While undertaking his duties there, the claimant was injured and sustained significant injuries to his body. As Jonathan was unhooking a trailer, a jack handle from the trailer struck him. He suffered from various broken bones on his face as well as a detached retina. Despite having sustained injuries while undertaking his routine activities, Jonathan was not compensated by Moore tires for these injuries. To determine the status of employment of the claimant to the organisation (Moore Tires), during the time when he sustained injuries, and whether he was undertaking the job that he was supposed to be doing within the company. The kind of claim that Jonathan is seeking can only be made to individuals who are employees of the company and this can be proved. The form of agreement that the claimant had with Moore Tires has not been clearly defined as a formal agreement or an informal agreement. As the proprietor of Morecedes Tires, the claimant had been undertaking other duties assigned by Moore Tires and was paid through Morecedes, which was an independent company. The activities that he was undertaking when he sustained the injuries could similarly be on the same capacity and this has not been defined. The employment contract must be produced to show evidence that the claimant was actually an employee of Moore Tires and not an independent contractor. There is also need to determine the employer’s right of control in the work relationship that existed between the claimant and the employer (Miller, 2012). If the control of the employment terms and condition of work lies within the employer, then the claims that are being made by

History of Modern Philosophy Essay Example for Free

History of Modern Philosophy Essay 1- How, and with what success, does Hume deal with the apparent anomaly of the missing shade of blue? In A Treatise of Human Nature, Hume attempt to rid 18th century moral philosophy of what he considered to be meaningless and vacuous concepts underlying our theory of knowledge be it metaphysical arguments or hypotheses seemingly formulated from the mere imagination of many philosophers. Influenced by the emerging trend of empiricism and naturalistic science like Newton and Locke, which Hume owed much of his basic principles from Hume presented the Treatise as an attempt to introduce experimental methods of reasoning into the area of moral philosophy. In the first book of the Treatise, entitled Of the Understanding, Hume devoted the first part Of the Origin of our Ideas for explaining the basis of his philosophical system that appeals on the similar empiricist approach as that of Lockes. However, curiously, Hume had cited an explicit counter-argument the problem of missing shade of blue that could invalidate his whole philosophical system that is based on this central principle. Even more puzzling is Humes complacency with this problem, and although he considers the problem as singular and exceptional, he fully admitted to this counter example and did not try to resolve it. Yet, this case merits a deeper investigation, and it is this essays attempt to see whether his apparent complacency with the missing shade of blue would have any effect on the strength of his philosophical system, and other attempts to render this problem irrelevant. The problem of the missing shade of blue by Hume is as follows: suppose a man who is well acquainted with colours for thirty years and has seen all the colours in the set of possible colour spectrum, except for one particular shade of blue. Then, he is presented with a full spectrum of the shades of blue, from the darkest shade to the darkest, all except the one particular shade in which he has not yet encountered. It is then conceivable that this man would be able to produce this single missing shade of blue. The problem of this lies in the basis of the empiricist doctrine at which Hume is following, namely, that all ideas must be preceded by experience, yet, in this example, it is demonstrated that it is possible for an idea to precede sensation experience, as the man is able to produce the idea of the missing shade of blue without having first encountered it through his senses. At this point, I would like to elaborate more on Humes theory of mind and the origin of ideas as that would clarify why this example is so damaging to Humes system. As stated before, Humes project can be put into a general label of empiricism, which is a belief that all knowledge comes from experience. Much of his line of argument resembles that of Lockes, another prominent empiricist. Hume even borrowed Lockes key terminology to a certain extent, with terms like ideas and impressions. Locke believes that ideas are whatever the mind perceives in itself, or is in the immediate object of perception, thought, or understanding, as when one perceives, thinks, or understands, the ideas are before the mind. This limits all ideas to be originated from experience (perception), and also shows the connection between thought and perception and their interchangeable nature. The ideas can be divided into ideas of sensation (touch, smell, sight, etc.) and ideas of reflection (fear, happiness, sadness, etc.), which can then be separated further into simple and complex ideas, where complex ideas are derived from simple ones. Hume follows this line of argument with some modifications. He claims he restores the term ideas to its original sense by classifying the objects the mind is perceiving as perceptions, not directly as ideas as Locke have used, and from perceptions he then distinguished them into impressions and ideas, where they differ in degree, as impressions are more vivid and forceful before the mind, such when sees a colour, and the ideas are more faint, such when one thinks of a colour after having the impressions of it. Hume then makes the distinction of simple and complex ideas, and by introspection, Hume demonstrates that one can think of any simple ideas and then find corresponding simple impressions that are exact copies of each other, and one can do this with any conceivable simple ideas. Complex ideas are different in that they are composites of simple ideas. And with this experiment in introspection, Hume then postulates his first thesis, That all our simple ideas in their first appearance are derivd from simple impressions, which are correspondent to them, and which they exactly represent. We may call this the Copy Principle, as it simply states that every simple idea is a copy of a corresponding impression. One of the most important components of this thesis is the fact that its a genetic one in that it shows the origin of ideas as following from impressions as impressions to be the cause of ideas. Again, this is proved by the constant conjunction of simple impressions preceding simple ideas, which one can do to every simple idea one may have. Another support Hume gives is that of a man born defective of certain perceptive organs, hence, missing certain impressions (e.g. sight or sound), one would not have any ideas of those corresponded with the impressions, for it is evident that deaf people also have great trouble speaking. The genetic component is important in that they validate the empiricism doctrine on the reliance of experience. Anyhow, now we can see how the problem seems to defeat the purpose of this thesis. Moreover, a counter example, from a logical standpoint, one counter example is sufficient to turn an argument invalid. So why did Hume not deal with this problem? We may try to take it as Hume claimed the problem to be a singular case where it is not worth investing time on. Being a singular case, one may have to take the argument in closer inspection. Hume states explicitly that the man in question may have enjoyed the sights for thirty years and perfectly well acquainted with all the possible colours except one, and that may be the attempt by him to restrict this to some specific scenario. It is implicitly embedded in the counter example that the subject of this example must be well acquainted with all the colours, such that one can make up colours in ones mind, much like how only musicians of a certain skill level can sight read music. Thus, it appeals to some amount of experience such that one may be bound to experience, habits, or personal background. Yet, when given further consideration, this seems to be invalid as well, as these restrictions do not seem to hold. As far as experience go, a child who does not know what turquoise mean does not necessarily have an idea of the colour turquoise. So this case is certainly not an exceptional case and Hume had not dealt with it satisfactorily. Yet, Humean scholars have tried to find solutions for this problem and some even disregard it as a problem altogether. Firstly, the first objection to this counter argument is that there is no way to test whether the person in question does in fact have an idea of the missing shade of blue before seeing the missing shade or not. There is a great difference between being able to spot a missing spot in a complete spectrum of blue, and being able to produce an idea of the shade of blue without first encountering the impression of it. If ones sees a constant change in shade from, lets say blue-0 where it is darkest to blue-255 where it is the lightest shade, then if there is one shade of blue missing, it would be quite noticeable as the mind notices the jump in gradual and constant change, but it does not follow that one could create an idea of that missing shade. To test this is also impossible, as if one is to reproduce colour, it still does not follow that he produces the idea since he would only be mixing the existing colours to brighter shades, and thus, after finishing mixing the colour, one then has the idea of the colour following the impression. All other ways of testing is equally futile because they all involve exposing the subject to the missing impression one way or another. Alternatively, if we look at the thesis again, and instead of taking it as a genetic form of the argument that Hume meant it to be, and instead, modifies it slightly to a more analytical empiricism form. Humes thesis on the theory of mind, upon closer inspection, can be taken as a form of meaning empiricism, in the sense that ideas to him are the same as different thoughts, which are different kinds of concepts, which is linked to when one understands something in a linguistic sense one is linking the word with the meaning, or the concepts associated to the word. Hence, if we think of the initial genetic content of the thesis, that impressions strictly precedes ideas, we may relax it slightly in favour of the analogy to meaning empiricism and forget its genetic form and instead formulate the following thesis: that all simple ideas must have corresponding conceivable and encounterable impressions. By doing this, we are no longer faced with the problem of the missing shade, since it is perfectly possible that the subject would be able to encounter this particular shade. Lastly, from a personal view, I see the problem of the missing shade of blue as not a problem at all, but Humes mistake lies in classifying colours as simple ideas. It is true that the impressions of light blue might very well be different than dark blue, so to speak, but to use Humes method, it is possible to separate using our imagination the components light and dark from blue. Thus, it is the impression of blueness which is a simple impression, combined with the impression of light and absent of light that combine to give this multitude of shades of colours. Take this example, suppose some neutral shade of blue, lets number it blue 124, were put somewhere with light, you will be able to see blue 124. However, lets say for some reason, the room becomes lighter, certainly, the shade of blue 124 would have changed to some lighter shade of perhaps blue 200. If we vary the light in the room from darkest to lightest, it is then possible to observe from the darkest to the lightest shade of blue likewise. One may argue that the colour can be calibrated to some objective criteria, perhaps the ratio of pigments of colour blue of some sort, yet, that does not matter since all that matters to Hume is indeed only impression. Furthermore, using this example, we can also say that perhaps the subject of the experiment may have in fact encountered the particular shade of blue sometime before without acknowledging it. Conclusively, although Humes treatment of the missing shade of blue is very limited and very complacent, it is perhaps Humes own mistake for considering such example a problem, rather than the problem itself being a threat to his theory of origins of ideas.

Theories of planned behavior: Smoking

Theories of planned behavior: Smoking To examine if the Theory of Planned Behavior (TPB) predict smoking behavior, 35 data sets (N= 267,977) have been synthesized, containing 219 effect sizes between the model variables using a meta-analytic structural equation modeling approach (MASEM). Consistent with the TPBs predictions, 1) smoking behavior was related to smoking intentions (weighted mean r =.30), 2) intentions were based on attitudes (weighted mean r =.16) and subjective norms (weighted mean r =.20). Consistent with TPBs hypotheses, perceived behavioral control was related to smoking intentions (weighted mean r = -.24) and behaviors (weighted mean r =-.20) and it contribute significantly to cigarette consumption. The strength of associations, however, was influenced by studies and participants characteristics. Smoking remains the leading preventable cause of death and disease in western countries. Despite the constant reduction in smoking prevalence among adults over the last 20 years in developed countries, smoking rates have not decreased among young people, and the highest youth smoking rates can be found in Central and Eastern Europe. In an attempt to understand the psychosocial determinants of smoking initiation and maintenance, a variety of social cognitive models have been applied. One of the most influential theories predicting smoking behavior, the Theory of Planned Behavior (TPB) 1has been used both for conducting a wide range of empirical research on smoking behavior antecedents and for designing many theory-based intervention programs to reduce tobacco consumption. An increasing number of empirical studies have examined this model in relation to smoke and the variability of results suggests that a quantitative integration of this literature would prove valuable. Up to the present, various quantitative reviews of the TPB have been performed but centered in other behavioral outcomes, as exercise, 2 condom use 3 and others. Hence, the purpose of this study was to evaluate the success of TPB as a predictor of smoking behavior through meta-analytic structural equation modeling (MASEM), involving the techniques of synthesizing correlation matrices and fitting SEM as suggested by Viswesvaran and Ones. 4 The TPB, an extension of the Theory of Reasoned Action,5 incorporates both social influences and personal factors as predictors, specifying a limited number of psychological variables that can influence a behavior, namely 1) intention; 2) attitude; 3) subjective norm (SN); and 4) perceived behavioral control (PBC). 1 First, subjective norms are conceptualized as the pressure that people perceive from important others to execute a behavior. Second, peoples positive or negative evaluations of their performing a behavior are conceptualized as other predictor of intention (attitudes). Third, PBC represents ones evaluation about the easy or difficulty of adopting the behavior and it is assumed to reflect the obstacles that one encountered in past behavioral performances. Finally, attitudes, SN and PBC are proposed to influence behavior through their influence on intentions, which summarize persons motivation to act in a particular manner and indicate how hard the person is willing to try and how much time and effort he or she is willing to devote in order to perform a behavior. 6 The TPB has been applied through a relevant amount of primary studies and their predictive utility has been proved meta-analytically both for a wide range of behaviors 7, 6 and for specific health risky or health protective behaviors. 3, 2 These previous meta-analyses, however, have neither examined how useful the TPB is to predict smoking behavior, nor the overall structure of the model applied to tobacco consumption. Hence, some concerns remain relating to TPB and its utility to predict smoking behavior that deserves further examination through MASEM. Firstly, a weakness of the SN-intention relation has been found by previous meta-analysis 7 compared with attitude-intention and PBC-intention associations. It has been suggested that this lack of association indicates that intentions are influenced primarily by personal factors 6. In spite of, some primary studies finding strong beta values, ranging from .44 to .62, for attitude on smoking intention such as Hanson, 8 while others founded values near .18 or .19. 9, 10 At the same time, although researchers have theorized about the importance of PBC in this domain, regarding health-risky behaviors, the correlation between PBC and behavior had sometimes been disappointing. 3 One possible explanation is that PBC may not capture actual control. Other is that risky behaviors performed in social contexts may be more determined by risky-conducive circumstances than by personal factors. 11 Moreover, primary studies on smoking behavior have found contrasting results for PBC -behavior, such as r =.55 12 or r =.06. 13 Based on these discrepant findings, we proposed, as a first purpose of this review, to test the strength of relationships between TPB constructs applied to smoking behavior. Secondly, in order to clarify the influence of moderator variables and to provide further explanation for the variability on the effect sizes (ES) between primary studies, some studies and participants characteristics may be taken into account. Ajzen and Fishbein 5 argued that intention and behavior should be measured as close in time as possible to the behavior. In spite of that, primary studies on smoking behavior 14, 15 have found that beta values for intention- behavior association have been maintained during six months (à ¯Ã‚ Ã‚ ¢=.38), nine months (à ¯Ã‚ Ã‚ ¢=.35) and a year (à ¯Ã‚ Ã‚ ¢=.35). Thus, it is important to quantitatively review the moderator effect of time interval on strength of TPB constructs. It has been recognized that culture provides a social context that affects prevalence of certain behaviors. Moreover, some studies have compared results of TPB applied to smoking behavior by using diverse ethnic groups into the USA, such as Hanson, 8 while a great amount of primary studies have expanded their applicability to different cultural contexts. 16, 15, 10 These studies have revealed contradictory results, such as for Puerto-Ricans and non-Hispanic whites, SN was not found as a significant predictor of intention, 8 while it was significant for African-American teenagers, or beta values for SN-behavior ranging from à ¯Ã‚ Ã‚ ¢=.20 for UK samples 17 to à ¯Ã‚ Ã‚ ¢ =.43 for Netherlanders students. 18 Hence, because of cultural differences with respect to the SN-outcomes association, there is a need to meta-analytically examine the moderator effect of culture. Ajzen and Fishbein 5 and Ajzen 19 also recommended scale correspondence of measures for intention to properly predict behavior. However, meta-analysis on TPB applied to exercise behavior have found that only 50% of examined studies had scale correspondence, 20 and that ES was the strongest for the intention-behavior association when studies had scale correspondence. 2 Based on these previous findings, we contend that a thorough examination of moderator effect of scale correspondence on strength of smoking intention and behavior relationships is needed. Research indicates that teenage years are associated with heightened sensitivity to SN 6 and differences have been found in previous meta-analyses between age groups regarding their intention -exercise behavior association. 2 At the same time, only one study has tested gender differences applying TPB to cigarette smoking, 13 founding that the model fitted better among female students. Despite the fact that no consistent evidence has been found relating to the moderator effect of age and gender on the TPB constructs association, we state that an exploratory analysis would be advisable. Thirdly, while previous studies on TPB on smoking behavior had used stepwise regression analyses, more recent ones apply SEM or path-analyses. When all TPB relationships were tested simultaneously, same patterns would change. For instance, after controlling the influence of intention, the PBC- behavior association would turn to negligible values (à ¯Ã‚ Ã‚ ¢=.05), such as Albarracà ­n et al 3 proved for condom use. Moreover, based on the fruitful results of meta-analysis obtained in many research domains, 3, 21, 22, 23, 24, 25 it can be beneficial to use meta-analytic structural equation modeling techniques (MASEM) in testing causal models, such as some authors suggested. 4, 26 Based on these methodological and conceptual issues, the main objective of this meta-analysis was threefold. The first objective was to test the strength of the relationships between the TPB constructs with the smoking behavior. Specifically, we hypothesized: (1) large ES for intention-behavior, PBC-intention, PBC-behavior, and attitude -intention; (2) moderate ES for SN- intention; (3) larger ES for intention-behavior than for PBC-behavior and (4) larger ES for PBC-intention and SN-intention than for attitude-intention. The second purpose was to test the influence of moderator variables on the relationships between the TPB constructs. Specifically, we proposed (5) larger ES for attitude- behavior, PBC- behavior, SN-behavior, and intention-behavior when measures have been taken simultaneously; (6) larger ES when the time interval was shorter; (7) the largest ES for SN-intention and SN- behavior when participants belong to a collectivist culture, coded as Others into the category orig in of the sample; (8) larger ES for attitude- intention, SN-intention, PBC-intention and intention -behavior when constructs have been measured with scale correspondence; and (9) mean age of the sample, percentage of males and year of publication would moderate the relationships among TPB constructs. The third purpose was to test the predictive utility of TPB on smoking behavior through MASEM analyses. Specifically, we hypothesized that: (10) intention and PBC will predict smoking behavior; (11) attitude, PBC, and SN will predict intention and (12) intention will be a stronger predictor of behavior than PBC. Method Literature search In order to locate relevant studies, we conducted a computerized bibliographic search of the PsycInfo, MedLine, ERIC, using the terms smoke, smoking behavior, nicotine, tobacco consumption, and TPB as keywords. We also conducted a manual search of journals that regularly published smoking behavior research. Descendent searches have been conducted based on the references section of retrieved studies specifically previous TPB meta-analyses including multiple behavioral outcomes- and some authors have been contacted to obtain unpublished papers. This processes resulted in 52 studies retrieved in full text to further screening. Inclusion and exclusion criteria A study was considered for this meta-analysis if it met the following inclusion criteria: (1) the study had to report quantitative research on TPB applied to smoking behavior; (2) the study had to report a Pearson correlation coefficient between TPB constructs or data that enable us to calculate ES. Upon closer examination of the remaining 52 studies, a total of 27 studies were included which provided an amount of 35 independent samples (N= 267,977) and 219 ES. A total amount of 25 studies were excluded. Reasons for elimination have been that TPB construct measures were not included (8 studies), i.e.: 27, or that the studies were focused on smoking cessation instead of on smoking behavior (17 studies), i.e.: 28, 29. Only one dissertation has been included and no unpublished papers have been obtained. The studies that focused on smoking cessation have been excluded because the outcome variable in the model-smoking behavior versus smoking cessation-differs substantially. These studies will be used to conduct a separate meta-analysis on smoking cessation. All the included studies are marked with an asterisk in the reference section. Coding of studies The study characteristics coded were: year of publication, origin of the sample, scale correspondence, and time interval between TPB measures. The subject characteristics coded were: the number or participants, mean age of the sample, and gender (as percentage of men in the sample). We consider relevant to code how smoking behavior was assessed (i.e., objective vs. self-report.) but we could find only one study which used objective measures, as CO (carbon monoxide) tests. 30 Following the procedures of Symons and Hausenblas, 2 the time interval between intention and behavior was examined by classifying the studies as: (1) short (less than or equal to six months), (2) medium (greater than six months and less than or equal to one year), (3) large (greater that one year). Regarding scale correspondence, we examined the method section of each study in search of the detailed information. Such as Symons and Hausenblas suggested 2, scale correspondence has been fulfilled when the same magni tude, frequencies or response formats are used to assess the constructs. If intention and behavior were measured exactly with the same items, we considered that scale equivalence was present. If intention was measured with a broader redaction (i.e.: How certain are you that you could resist smoking this term?) while behavior was assessed by a more detailed item (i.e.: How many cigarettes did you smoke per day?), or by asking participants to classify themselves as non-smoker/current-smoker, we considered that scale correspondence has not been fulfilled. In order to ensure accuracy, the studies were coded by two authors independently, reaching an intercoder agreement of 90%. The level of agreement reached was highly satisfactory and inconsistencies were solved by consensus. Some decisions about independence of the samples were taken. If the same study design was carried out in multiple but independent samples (i. e, boys and girls, asthmatic and no-asthmatic students, African-American, Puerto Rican and Non-Hispanic white teenagers) results were entered into the meta-analysis as independent samples. 8, 18, 13 In other cases, only one ES per study has been considered. Data analysis We followed Hedges and Oldkins 31 meta-analytic fixed effects procedures to estimate weighted mean correlations. In these procedures, correlations were converted using Fishers r to z transformations and weighted by N 3, the inverse of which is the variance of z, in analyses. Using Cohens criteria, 32 ES values of .10, .30 and .50 were considered small, moderate and large effects, respectively. Graphical procedures were used to explore the skewness of data. When an extreme value was detected, analyses were carried both including and excluding the outlier. Next, we tested the homogeneity of the ES (Q statistics) and we analyzed the influence of moderator variables using categorical model (ANOVA analogous) and weighted regression analyses (fixed-effect model). One problem in the interpretation of meta-analytic results is the potential bias of the mean ES due to sampling error or to systematic omission of studies that are hard to locate. According to Orwin, 33 the tolerance index of nul l results should be calculated and there must be more than 300 unpublished studies (and not recovered by the meta-analyst) for the results to be annulled. However, this statement should be qualified because the index by categories yields small values in some of these categories. Therefore, we can conclude that publication bias is not very likely to threaten the results severely. MASEM analyses Meta-analytic structural equation modeling, which involves the techniques of synthesizing correlation matrices and fitting SEM, is usually done by applying meta-analytic techniques on a series of correlation matrices to create a pooled correlation matrix, which then can be analyzed using SEM, as suggested Viswesvaran and Ones. 4 However, these procedures have received criticism by Becker (1992) and more recently by Cheung and Chan. 26 Despite some problems, the major advantage of these univariate approaches are their ease of application in applied contexts. Based on these recommendations, we used Viswesvaran and Ones procedure to test the strength of the association among the TPB constructs with smoking behavior. The complete weighted correlation matrix was 5 x 5 and it was submitted to SEM analyses. The predicted model was fitted assuming the harmonic mean (N= 239) as sample size, 4 and it was estimated with unweighted least squares procedures. The proposed model, according to TPB l iterature, had three exogenous latent variables and two endogenous ones, such as depicted Figure 1. Besides chi-square, we reported Goodness of Fit Index (GFI), Adjusted Goodness of Fit Index (AGFI), Normative Fit Index (NFI), and Root Mean Squared Residual (RMR) as fitness indices. It is typically assumed that GFI, AGFI, and NFI >=.90, RMR values

A Feminist Reading of Updikes Rabbit, Run Essay -- Feminism Feminist

A Feminist Reading of Rabbit, Run  Ã‚        Ã‚  Ã‚   I do not like Harry "Rabbit" Angstrom. This creation of John Updike, this man who abandons his pregnant wife and young child, and his alliance to the late 1950's feeling of unrest and rebellion makes me angry. Many times throughout this novel my cheeks flushed furiously and I could not contain my exasperated sighs. When I read the last sentences of Rabbit, Run and closed the book, I was disappointed. It was not because Updike fails to make it clear where or to whom Rabbit runs (home to his wife? back to the prostitute?). Surprisingly, I was most disappointed because the novel had come to an end. Although my reaction to Rabbit was negative, it was a very strong reaction; I had become emotionally involved. Because Updike created this anti-heroic but fascinating main character, I was absorbed into his world. I do not like Harry "Rabbit" Angstrom, but because Updike's writerly skill, I understand him. And, by understanding him, I am able to realize the importance his place i s among the most influential (particularly American) literary characters.   Part of the reason that Updike's novel (and the subsequent three Rabbit novels to follow) has become such an essential piece of literature in the American tradition is Rabbit himself. Although he is not likeable, there are various important aspects and depths to the character of Harry Angstrom that cannot be overlooked. Some critics choose to look at the surface and explore Rabbit's nature comparatively with rabbits (the animal). There are many instances when we do see Rabbit acting much like his namesake. For example when he visits his parents home Updike describes this in very rabbit-like terms: Rabbit stealthily approaches hi... ...h him for anything.    Works Cited Detweiler, Robert. John Updike. Indianapolis: Indiana University, 1984. 33-45.    Kielland-Lund, Erik. "The Americanness of Rabbit, Run: A Transatlantic View." New Essays on Rabbit, Run. Ed. Stanley Trachtenberg. Cambridge: Cambridge University Press, 1993. 77-94.    O'Connell, Mary. Updike and the Patriarchal Dilemma. Carbondale, IL: Southern Illinois University Press, 1996. 13-36.    Pinsker, Sanford. "Restlessness in the 1950s: What Made Rabbit Run?" New Essays on Rabbit, Run. Ed. Stanley Trachtenberg. Cambridge: Cambridge University Press, 1993. 53-76.    Stevick, Philip. "The Full Range of Updike's Prose." New Essays on Rabbit, Run. Ed. Stanley Trachtenberg. Cambridge: Cambridge University Press, 1993. 31-52.    Updike, John. Rabbit, Run. New York: Alfred A. Knopf, 1960.   

Relationship between humans and nature Essay

Marlowe in his poem ‘The passionate shepherd to his love’ talks of the strong link between humans and the nature that surrounds them. The poem from beginning to the end talks mainly of the nature that surrounds us wherever we go. The poem makes us understand that we are actually dependent on nature for all our needs. The nature in its splendor is so beautiful that Marlowe has actually united with the environment. The poem captures the joy of love, in the midst of nature. In fact reading the poem makes one wonder, if the natural splendor that surrounded Marlowe when he wrote the poem, was the reason for his love to flow like a river. Nature makes one forget about the present. In fact, it makes us forget all about ourselves and become one with nature as we enjoy and be part of the beauty that surrounds us in all its glory. Marlowe in this poem talks more of the nature that surrounds him and less about his love. The poem talks of the quiet simplicity of rural life and how humans are part of nature. There is no way of separating humans from nature. The humans are dependent on nature for their very existence. The nature is dependent on humans to be admired and glorified. The human dependence on nature is highlighted by the fact that Marlowe is sitting upon a rock. He wants to make a bed of roses; wool for a coat from the lambs, buckles for the slippers from gold, a belt of straw, the list goes on. Marlowe by writing this poem has made the readers understand the relationship between humans and nature. Annie Dillard in ‘Sojourner’ talks of the Earth in its entire splendor. She talks of the mangrove tree that floats and becomes like an island in a sense. She rediscovers the magic of nature and how it can be viewed in a beautiful sense. People ordinarily will not give a second thought to a tree floating. She magnifies the significance and projects a simple natural event into something extraordinary. In fact Annie Dillard brings to life the mangrove tree that is all but dead. A tree that has no life has been brought to life with her words. When Dillard talks about the mangrove tree, she actually means the Earth and its movements. She tells that Earth is a sojourner, creating its own path and moves in a path that cannot be followed by any other thing on Earth. She tells that Earth is a wet ball thrown into eternity and humans are part of this. We the humans and nature have united to become one. She ends with a question asking what will happen at the end of the journey. The mangrove tree will finally end up in the Ocean. So where do the Earth and the humans living on it finally end up, is a question left unanswered. Mangroves play a major role in the essay by Annie Dillard. She uses the tree to show the human nature. The mangrove starts from scratch and builds a strong foundation. The human nature and relationships are similar. We all start from scratch and build many strong relationships as we grow. Some who are not able to make any relationships are like the mangrove tree felled by the hurricane, being tossed and not knowing the final destination. Annie Dillard unites with nature and is part of it. She talks of the Earths movement in words that make a person imagine and feel the true aura of nature. She has merged the human nature and the nature to be examples of each other.

Creativity and Creative Industries

Creativity and Creative Industries Introduction: Creativity and creative industries Creativity can be referred to as developing of a new substance that has never existed; it could be a solution or product. Creativity occurs if one invents something new that has never existed, or if it exists elsewhere, the creator is not aware of it.Advertising We will write a custom essay sample on Creativity and Creative Industries specifically for you for only $16.05 $11/page Learn More Creativity can also refer to a new process of tackling something or inventing a new idea. One can also introduce an existing product into a totally different market. With the emerging technology, upcoming industrious people are able to create their work and hence establishing outlets for their creativity as a way of promoting and distributing their creative work. The creative industries may include design, architecture, writing and publishing, music, photography, and performing arts. The screen production such as in the tel evision is inclusive. Hence, creative industries are economic activities that concentrate on the generation of knowledge and ideas. These industries are usually as a result of an individual creativeness inclusive of talents and skills (Queensland University of technology, n.d). Nevertheless, the creative industries contribute widely in a country’s economy due to their uniqueness in their operations, thus attracting many clients from within and abroad. Creativity yields creative industries, which in turn lead to employment, growth, and development in a country. Hence, creative industries contribute to gross domestic product (GDP), in distribution term and job creation (Henry, 2007, pp 9). To build creative organizations, knowledge and leadership is required; therefore, the presence of an ideal leader is important. This is a person who has the capabilities of spotting an idea that suits well with the needs of an organization.Advertising Looking for essay on business ec onomics? Let's see if we can help you! Get your first paper with 15% OFF Learn More He is an entrepreneur who finds ways of selling and guiding his/her through implementation. He is however conscious of how his ideas can be affected by contradicting actions of managers who are not keen. However, creativity is challenged by several factors, for instance, it is not easy to demonstrate the value of a new service or product that is not in existence. New ideas may be threatening to the existing market; nevertheless, if they sail through, developing of these ideas in to tangible products may be an easy task. There are a number of factors that an ideal leader should consider including the surrounding environment, which must promote idea generation. Scanning for new opportunities should be done continuously by clarifying the emerging problem. Practical techniques should also be implemented to encourage the generation of new possibilities. When the idea is finally implemented , a follow-up should be done regularly to ensure that the idea follows the right track (Arnold, 2010). Creativity can fall in many categories, for instance, the private health sectors. In is evident that private hospitals have more medical facilities as compared to public hospitals, which are limited to facilities. This is most evident in developing countries where a patient has to be referred to a private hospital to be attended. This may be due to the fact that a certain machine is only available in a certain private hospital. The profound point here is that, the management of such a hospital thought through how to attract patients or gain fame as a hospital. They then opted to import an expensive life saving machine form abroad, after surveying and discovering that such a machine does not exist in any of the hospitals in that country.Advertising We will write a custom essay sample on Creativity and Creative Industries specifically for you for only $16.05 $11/page Learn More Such an idea changes the lives of many people in the society, from the patient to the new employees / experts needed to operate the machine. Another example could be establishing a borehole in a community that has scarcity of water and by use of technology, pumping the water to taps. The business can decide on how to charge for the water service, thus making a community’s life easier and at the same time making money. Creativity is what gives sight to the blind, and what provides a better heart to the children with a heart condition. Through creativity, these surgeries are innovated, studied, and taught to medical specialists such that, when they perform the surgeries, they are a success. Therefore, everything in our lives revolves around creativity, which develops into ideas that form creative industries that deal with different products and services. Hence, creativity has contributed greatly to the community in that, it provides quality life for people in the society, and this is evident through a number of creative industries that surround us; architecture, designs, advertising, software, publishing, internet, electronics, infrastructure, among others. With technological know-how, our live move a little fast, since we no longer have to send an urgent letter via post office that task can be completed through an instant chat message or through yahoo-mail or face book. Despite the importance associated with creative industries, the cultural industries are also of benefit to a country such as the museums. However, it is due to their tradition state probably shuns visitors away; nevertheless, creative industries can boost such industries technologically to revive their fame.Advertising Looking for essay on business economics? Let's see if we can help you! Get your first paper with 15% OFF Learn More The creative industries can also contribute to the cultural industries via architectural services, thus improving the outward image of these heritages. The internet has emerged as a result of creative industries, with its presence tasks are completed faster and communication is much easier due to the social clouds like facebook, my space among others. Information can also be acquired fast due to the search sites such as; Google, wikipedia and yahoo among others which can be referred to as information clouds. With the emerge of cloud culture, the internet has enabled exchange of information through chatting which enables one to express themselves and understand other peoples culture through interaction with other online communities. Culture gives us a sense of belonging and identity and hence through sharing of information and interaction, through clouds such as facebook, twitter and my space among others. Knowledge is the key to success, since it is through knowledge that one can be able to develop a generated idea. However, according to Arnold (2010), creativity may be faced by obstacles if the organization’s culture, does not entertain new ideas, but instead it criticizes them. Management may not be willing to take risks, thus hindering implementation of ideas. In organization where workload is routine and unrealistic expectations are required, it proofs difficult for the creativity to occur, since employee are always occupied with work. New Zealand’s creative industries According to a journal by Fritsch (2008), creativity is seen as a process mostly, other than a product in the earlier years, people used their own skills and to expand. In addition, with the presence of creative process, it leads to creative production and if creative output is emphasized, definitely a creative outcome results, hence leading to an economic success. The creative industries in New Zealand lead to the creation of goods, services, and knowledge in the textile, des ign, fashion, production, art and even in the photography sector. According to Grants et al (2009), the New Zealand creative industries led to 121,000 jobs in 2006; nevertheless, this sector led to increase of incomes, such that, as in 2006, the employee earned about $52,000 per year. A community creates a relationship that encourages the exchange of ideas and risk taking in a business environment. Nevertheless, the relationship in creative industries included a number of elements among them being an idea, which resulted to a process, experience, innovation, and collaboration. Creative industries are a part of Auckland, which is in New Zealand. According to Bruin (2005, pp 143), the creative industries in New Zealand are well acknowledged since it is believed to be a major contributor to the country’s economy. The New Zealand film industry is an example of a creative industry, which has over the years, attained recognition internationally by participating in movie production. For instance, the return of the lords, the whale rider, resulted to winning of an award like the Oscar for the actors, directors, screen artist, and digital animators in 2004. Due to technology, New Zealand has special effects on their productions, hence producing awards of this approach are evident in the innocentive company that broadcasts scientific questions for scientists to solve. Thirdly is the peer-vetted creative production approach, that is applicable in cases where no right answer exists thus, the online community task is find an answer that will respond to the customer’s tastes and preferences. Threadless is one of the companies that use this approach, where assigns a t-shirt design competition to the public. The distributed human intelligence tasking is the final approach, which is used when human intelligence tasks need to be tackled. Crowdsourcing organizations normally apply this approach when a lot of labor is required to organize piles of information in a p articular systematic way. Hence the crowdsourcing organization distributes the data online for the online communities to handle it. Amazon mechanics Turk is a company that allows organizations to hire an online community that can perform human intelligence tasks. However crowdsourcing faces critiques on its functionality, people tend to think that crowdsourcing organizations exploit an individual’s talent for the organization’s benefit; however, the online community participates willingly without being forced to and if any of their ideas win, they are then rewarded (Braham 2011, pp 6). The interaction between the creative industries and the cultural industries Creative industries are yielded from cultural industries. The difference is that the creative industries trend with up-to-date technology as opposed to the cultural industries. The cultural industries emerged in the early years and even then, people were creative as they are today. The creativity within culture i s evident in the way crops were grown from sowing seeds, and meat products were extracted from rearing animal, while wood was retrieved from growing of trees. Therefore, culture mostly relate to the past activities. Some of the cultural industries include broadcasting, internet, music, publishing, advertising, and even marketing industries. Some of the cultural products like the theatres have been modernized to big screen cinema, and in homes, the televisions are used to convey messages. Nevertheless, cultural institutions like the museums are present, thus portraying the past years of culture through exhibition of the old culture and traditions. Such cultural industries normally contribute to the economy of a country via tourism. Creative industries can be seen as a part of the cultural industries, since some cultural industries can be said to be creative in nature. The interaction between these two industries can be seen in this example of the music industry; a songwriter is the o ne who generates a unique idea of a song, â€Å"which is performed by artists in recording studios, then modified and produced by engineers, and then reproduced, marketed and distributed by record labelsâ€Å" (Brabham, 2008). Nevertheless, technology has contributed to creative industries due the easy accessibility of internet that can contribute to the growth of an idea, because of research. However, in the case of music industry where music is recorded on CDs and MP3s nowadays, they are also prone to creative destruction like piracy, thus interfering with the original targeted sales, leading to losses eventually. Nevertheless, these two industries have their differences, the table below explains: Fig 1: Table illustrating the differences between the creative industries and the commercial industries Cultural industries Creative industries Use low technology in its operation They use high technology, in terms of internet. In case of the museums and art gallery, customers n eeds are ranged a secondary. They target customer needs so as to develop They are not commercial at all. Concerned in innovation and entrepreneurship. They mostly focus on education matters like the museums. Their focus is on knowledge and information, so as to develop unique products. Employees in these industry are academics and artists, They employees here are interested in business and are mostly entrepreneurs. Its employees often have acquired high level of knowledge in academics. Technology is not an issue These industries employ employees on the basis of skills and knowledge. And must be familiar with the demanding technology. The employees’ salaries are usually low, since most of their work is based on interest. Employees in this industry are rewarded via money and reputation. The profound point here is that, the creative industries are privately funded and are modernized in contrast to the cultural industries, which mainly belong to a state and are tradi tion-based. Nevertheless, the main challenge that face the creative industry is mainly uncertainty in demand, because the goods produced depend solely on the preference of the customer, therefore, rendering it difficult to estimate the sales to be made. Hence, their main aim is to satisfy a customer, thus hoping that their products will be identified by the customers. Employees in such companies attribute their work to quality of what they produce, since the aim of creative industries is to maximize on their profits. However, product of creative industries differs in terms of quality, symbolism, aesthetics, and styles associated with the product. These industries work against time and therefore must comply with the time given. This usually applies to even their staff. In addition, their products are usually durable, such that they can be used repeatedly; an example is a video game (Puchta et al, 2010 pp 32- 35). Creativity contribution to the cultural industries Cultural industries can be enhance in a creative approach, for instance, by use of architecture and design whereby, through creativity, outstanding buildings can be redesigned and developed, thus emerging as unique and enhance their appearance; this can apply to museums. Secondly, the cultural industries should aim in adopting a creative approach in the marketing and branding area so that they can achieve a competitive advantage, hence be in a position to compete at global level, and even attract local tourists. The cultural industries should be able to embrace technology in their operations, thus being at a competitive advantage since they will be advanced technologically. The lack of commercial experience by the cultural industries, hence the creative entrepreneurs can assist in commercializing these sectors. The goods and products of these two industries vary in terms of ownership. Cultural industry goods are usually state owned thus described as the public goods, which are run by non-profitable org anization, while the creative industries are privately run and their good and services are marketed and distributed to convenient customers. In addition, these industries have to be at a competitive advantage in order to survive in the competitive market. According to Smith (2009, pp 153), the main reason why cultural industries are no longer a concern for visitors is because they seem old fashioned and less fun and attractive, hence people prefer visiting the cinemas, and watching soap operas on the television as a way of spending their leisure time. However, if these old heritages were renovated and a state of modernity is installed, then they would receive many audiences, not only for educational matters but also for leisure purposes. Conclusion Creativity is the source of developments across the world, since it leads to a creative society, which also yields to a creative economy that generates huge profits for its country, and in return provides of job opportunities and developm ent in the society. Without creativity, human beings cannot survive, thus thinking out of the box is what makes nations develop and earn profits. People’s living standards also improve due to creativity, since new source of incomes develop thus providing employment to the society; thus, a relationship between creativity and the society is build. Creativity is however, a major competitive factor in a country, due to the inclusiveness of technology, which is also a key to competition that may positively or negatively affect a product. Since creativity depends on one’s skill or talent, it literally affects the process of production. Creativity yields to external and internal benefits such that the external benefits are evident as an innovative idea while internal benefits of creativity are evident in job satisfaction and a person’s well-being, hence, these factors should be encouraged in organizations. Nevertheless, creativity should be incorporated to the cultural industries to develop them technologically such as good infrastructure, which could include wireless internet in public buildings. Crowdsourcing is evident in creative industries whereby tasks are distributed to the public for experts to tackle them. This practice is very efficient since the crowdsourcing company generates a variety of ideas and chooses the best among them. Though crowdsourcing is criticized for exploiting the community’s ideas, an organization benefits fully from this process and the winning idea is rewarded. The internet has brought about easy accessibility to information and communication has been made easier, effective and fast, thus yielding to many clouds in the community. Cloud culture for instance is a way in which different culture may be expressed, however cloud culture can only contribute to creativity if people are willing to cooperate, share and create information. Culture provides a sense of identity to people while creativity contributes to gr owth as culture stabilizes the society. It is however clear that the internet has benefited the world and made life easier. References Anon. (2011). Creative industries. Retrieved from http://business.newzealand.com/Industries/15245.aspx#apparel. Arnold, A. (2010). Building a creative organization. Business week. Retrieved from businessweek.com/managing/content/sep2010/ca2010091_968396.htm. Braham, D. (2011). Crowdsourcing: A draft on; A Model for Leveraging Online Communities. Retrieved from http://dbrabham.files.wordpress.com/2011/03/brabham_handbook_crowdsourcing.pdf. Brabham, D. (2008). A convergence article; Crowd sourcing as a Model for; Problem Solving. NY: Sage publishing. Bruin, A. (2005). Multi-level entrepreneurship in the creative industries New Zealand’s screen production industry. Retrieved from http://sme-centre.massey.ac.nz/files/deBruinMulit-level_entrepreneurship.pdf. Flew, T. (N.d). Beyond ad hocery: Defining Creative Industries; Media Communication. Creat ive Industries Faculty. Queensland University of Technology. Retrieved from http://eprints.qut.edu.au/256/1/Flew_beyond.pdf. Fritsc, J. (N.d). Can a ‘Communities of Practice’ framework be applied to the creative industries as an identified audience for the VA? Head of Gallery Interpretation, Evaluation Resources, VA. Retrieved from vam.ac.uk/content/journals/research-journal/issue-01/can-a-communities-of-practice-framework-be-applied-to-the-creative-industries-as-an-identified-audience-for-the-v-and-a/. Grant, A. et al. (2009). The creative sector in New Zealand: mapping and economic role: report to New Zealand Trade and Enterprise. Retrieved from http://eprints.qut.edu.au/31133/. Haavisto, V. (N.d). University of Art and Design Helsinki UIAH School of Design. Toward a creative society; embracing the diversity of creativity. Retrieved from etla.fi/files/1253_FES_04_3_towards_a_creative_society.pdf. Hagoort, G., and Kooyman, R. (N.d). Creative Industries. NY: Eburon Uit geverij B.V. Publisher. Henry, C. (2007). Entrepreneurship in the creative industries: an international perspective. London: Edward Elgar Publishing. Leadbeater, C. (2010). Cloud culture; the future of global cultural relations. (Attached material). Leadbeater, C. (2010). Cloud culture: the promise and the threat. [2.2.10]. edge foundation Inc publishers. Retrieved from edge.org/3rd_culture/leadbeater10/leadbeater10_index.html. Montgomery, L. (2011). Chinas Creative Industries: Copyright, Social Network Markets and the Business of Culture in a Digital Age. London: Edward Elgar Publishing. Potts, J. et al. (2008). Social network markets: a new definition of the creative industries Journal of Cultural Economics; Volume 32, Number 3 / September 167-185. Retrieved from http://eprints.qut.edu.au/18071/2/18071.pdf. Puchta, D. et al. (2010). The Berlin Creative Industries. Berlin: Gabler Verlag Publisher. Queensland University of technology. (N.d). what are the Creative Industries? Retriev ed from creativeindustries.qut.edu.au/about/what-are-the-creative-industries/ Schmit, G. (N.d). Can Creativity Be Crowd sourced? New Tools and Technology Force Big Changes in the Ad Industry. Ad Age Digital. Retrieved from http://adage.com/article/digitalnext/tools-technology-force-big-ad-industry/136019/. Simpson, M. (N.d). The Importance of Creativity on Our Global Society and in Today’s Educational System; Baylor University. Retrieved from wfate.org/papers/Power_and_Influence_of_the_Right_Brain.pdf Smith, M. (2009). Issues in Cultural Tourism Studies. Second edition. London: Taylor Francis Publisher. UK trade and investment. (N.d). Creative and media sector in New Zealand. Retrieved from www.ukti.gov.uk//Creative%20sector%20in%20New%20Zealand.pdf.html.

Free Essays on Single Subject Design

Free Essays on Single Subject Design INTRODUCTION Self-control programs, in which one is taught to control one’s own behavior by devising antecedent and consequent events, have been gaining in popularity for quite some time now. A central aspect of these programs is self-reinforcement, in which a subject self-administers reinforcers dependent upon requisite performance. Self-reinforcement techniques have been shown to alter therapeutically a wide variety of behaviors, including studying, eating, depression and smoking, in both educational and clinical settings (Nelson, Hayes, Spong, Jarrett if the consequences are postponed, intermediate cues may be mislabeled as self-reinforcement. In a study conducted by Nelson, Hayes, Spong, Jarrett and McKnight (19...

College Campus Smoking Bans essays

College Campus Smoking Bans essays Today about four hundred thousand Americans die annually because of the health problem due to smoking. One and a half million people quit smoking a year, but more than fifty millions people continue to smoke. Smoking is one of the most major public health issues in America. The largest population of smokers in the country are college students. Tobacco companies mostly use advertisements that draw college students in. As of October 5, 2012, at least 826 colleges or universities in the U.S. have adopted 100% smoke free campus policies. These policies eliminate smoking in indoor and outdoor areas across the entire campus including residences. Just to name a few in Pennsylvania you have, Keystone College, Lackawanna College, Widener University, and Lehigh Carbon Community College. In the list of campus in Pennsylvania, Northampton Community College is nowhere on the list. Northampton still allows students to smoke in their cars, and in designated spots around their facilities. I purpose that they ban all smoking on campus, and offer a penalty for those who violate a 100 percent campus smoking ban. It is reasonable for some to argue that smoking on campus is not healthy for smokers or non-smokers. As we all know, smoking is detrimental to our health. Every year a large amount of people die from diseases caused by smoking cigarettes such as lung cancers, heart diseases and stroke. There is a mixture of nicotine and carbon monoxide in each cigarette. Which can cause an increase in your heart rate and blood pressure. It can also cause straining in your heart and blood vessels. Even though people know all these facts they still continue to smoke. Right now the issue on smoking causes a lot of mixed feelings in people. Some people hate smoking because lung cancer claimed a loved one. Others dont like it because it causes secondhand smoke which is just as unhealthy. Secondhand smoke is also called environmental tobacco smoke, in...

Communication Research Assignment Example | Topics and Well Written Essays - 750 words - 2

Communication Research - Assignment Example This is where the all the data comes from.> Might be helpful to the class if you mentioned why Qual research doesn’t do sampling? Qualitative research doesn’t do sampling because unlike in quantitative research which rely heavily on sample size as the key drivers for statistical analysis, qualitative research rely more on observation and the interpretations are mostly value-bound. Qualitative research is subjective in nature while quantitative research is objective. Given the context and implications of the use of sampling in a research study, it is important to ensure that the sample size chosen is appropriate and adequate in order to derive effective results from the study. Since the analysis of the data relies heavily on the sampling methods used as well as on the sample size it is highly crucial to ensure that the chosen method is apt for the research study. However determining an appropriate sample size is highly tedious process and the researchers are generally found to be vulnerable to random sampling errors. These sampling errors encountered by researchers refer to ascertaining the appropriate sample size and disregarding the response and non-response bias Yes. Response bias means when the respondents answer in accordance with what they perceive the researcher expects them to answer rather than relying on their own personal beliefs. Non-response bias occurs in statistical surveys and refers to the difference between the answers provided by the respondents and those likely to be provided by potential respondents who did not participate in the study (Wunsch, 1986). The key advantages of sampling is that it allows the researchers to use numbers as a tool to assign value to a given phenomenon and derive meaning out of the numerical data, collected by them (Keyton, 2011). Quantitative research enables the researchers to use/ select smaller groups or

The Emergence of Modern Science Essay Example | Topics and Well Written Essays - 250 words

The Emergence of Modern Science - Essay Example Whereas it is healthy to ask critical questions, scientific proof, and evidence, accepting the scientific reality is a necessity. For instance, whereas our ancestors gladly accepted polio vaccine and eradicated polio, it is overwhelmingly difficult for present generation to accept genetically modified foods as a solution to rising food crisis. As argued by Michael Specter, healthy skepticism calls for asking the right questions, at the right time, to the right people. Pinpointing a problem is also a prerequisite to healthy skepticism. 3. A healthy skepticism requires an understanding between correlation and causation. Learning widely and gaining all round knowledge provides a basis for unbiased skepticism. Additionally, critical review of previous fundamental scientific theories makes it possible to question scientific knowledge based on scientific questions and scientific assumptions. 4. Articulate use of brains is one of the key to success in education. Understanding the unlimited relations between brain hemispheres is overwhelming. However, understanding that such relations exist makes it possible to prepare psychologically to expect, accept, interpret, and analyze wide array of knowledge. I hope to learn more about how brain hemispheres work in preparation for optimal use of brain resources. 5. Whereas it has been argued that schools kill creativity, I believe creativity starts with oneself and can be nurtured with time. Going beyond classwork and course books for search of knowledge is a prerequisite for creativity. Working in tandem with lecturers and like minded students will go a long way into cultivation creativity in my journey through UHD. 6. The first cartoon is funny because it depict a scientist in denial of scientific evidence. Whereas many scientists are looking hard for evidence to support theoretical predictions, it is funny that a scientist would disregard archaeological evidence of evolution in first the first

Report Assignment Example | Topics and Well Written Essays - 2500 words - 1

Report - Assignment Example You may as well think about both your fleeting procedures and long haul objectives in the arranging stage, giving careful consideration to contrasting the dangers and the potential The Marketing Process rewards. When you have improved a plainly characterized marketing arrangement, you can start the usage stage. The triumph or disappointment of the usage stage depends practically altogether on the work you have finished in the examination and arranging stages. In the event that your arrangements are practical, well thoroughly considered and dependent upon sound investigation, the execution stage may as well bring about triumph for your business. It is vital to remain concentrated on your target goals throughout the execution stage and be readied to acclimate your arrangements to suit evolving conditions. We have to be attentive to changing economic situations, our rivals and clients and alter marketing techniques in like manner. These fundamental standards of marketing apply to all business sectors far and wide. Coca-Cola is extremely market orientated, accompanying the arrival of distinctive products, for example, Coke Lime flavour, and diet Coke. They went under far reaching statistical surveying to discover what individuals preferred, and regulating around the range of 59% of the planet market. Coca-Cola is the drink that gives where it counts down refreshment for the brain, figure and soul since just ice-frosty Coca-Cola makes a minute more uncommon by joining together the extraordinary Coca-Cola sensation with whats true and bona fide giving a wellspring of satisfaction in regular life. Coca-Cola customers are not just restricted to just drinking Coca-Cola, they can look over an assortment of juices, games beverages, and mineral waters. Despite the fact that carbonated beverages are their biggest development fragment, the Asia showcase alone has around 3.2 billion buyers. Globally, Coca-Cola

Terrorism Affecting The World Economy Essay Example | Topics and Well Written Essays - 750 words

Terrorism Affecting The World Economy - Essay Example To trigger development, it encouraged the formation of rural enterprises, liberalized foreign trade and investment, introduced education reforms, and invested heavily in industrial production. In several peak years, the GDP hit as high as 13 % and today the per capita income has quadrupled compared to what it was 15 years and if the predictions by various analysts hold true, the Chinese economy will cross that of United States in another 20 years. (Khan 2007) According to a research conducted by IMF in an attempt to find the key sources of its growth, it was found that the increase in the number of Chinese workers has been one of the major factors of its growth. At the same time capital accumulation through the growth in the overall assets of the country, new factories, manufacturing machinery and development in its communication systems have also marked its growth. According to most theoretical and empirical analysis conducted, more than 42 percent of china's growth has to do with productivity gains since 1979-94 but after 1994 capital took over as the most significant and primary source of growth. This marks an avid departure from the more traditional views on development wherein capital investment takes the lead. In most cases, economists studying Chinese Growth have faced lots of theoretical and empirical issues most of which cr... It elaborates over the link between productive factors such as capital and labour to output. This model is mostly applied to market economies but can also be used for command economies. In addition, finding from such empirically modelled data has led to the conclusion that in recent year's capital investment in goods and technology have led to increase in productivity. (A Measurement of the Contribution Made by Foreign Investment 2005) India: India has shown remarkable economic growth for the past three years of its running. For a decade, it has been registering an economic growth of 7% plus which has led to reduction in poverty by 10 %. However 60% of India's population continues to thrive on agriculture which makes a poverty alleviation a major economic channel. The fact that droughts and floods are still common in the nation, does not sit too well with the agents of economic growth. According to a hypothetical analysis that was recently conducted, one main reason behind India's economic growth has been the structural transformation that has been adopted by the national government. India's economic growth has been oft conceived as directly related to that of its performance in the service sector in particular. Its growth rate was above 11 % in 2007 and contributes to 53 % of GDP today. Investment in industrial sector has been another key component of its growth and it contributes to 29% of its GDP where as agriculture is 17 % of its economy. Manufacturing sector has emerged rapidly and has shown remarkable progress between 2005 and 2006. It grew by 12 % during this time where as communication and storage sectors grew by 16 %. (Indian Economy overview

I have an article need to be reviewed Example | Topics and Well Written Essays - 1000 words

I have an need to be reviewed - Article Example Chris Howell has a Doctor of Philosophy from Yale University, while Rebecca Kolins Gavin has a doctorate in Political Science from Northwestern University. Their work has been cited 14 times since it was published in 2011. Comparative political economy claims that institutions are important because they mediate economic pressures, distribute powers among actors, and offers solutions to problems that are faced by market economies (Hall & Taylor 1996). The authors have focused on the political economic approach, developed by Frege and Kelly (2013), in which the focus is on the historical and institutional roots of employment regimes and institutions. They have described in detail the role of the state in the development of industrial relations in all three countries, but have given limited description about the role of the market factors in these events. The Varieties of Capitalism (VOC) model (Hall & Soskice 2001) has been used to try to understand and compare the patterns of industrial relations and institutional changes in the three countries. It is mentioned in the article that institutions are not able to perform in isolation, and that there will be interactions and complementarities between them as suggested by the VOC model. The Dunlop system theory has assumed that common technologies and cross-national markets would create convergence towards a common model of employment regulation. A feature of the period since the mid-1980s can support this claim where it can be observed that even though there have been differences in the policies and details accompanying reform, the direction of institutional change has been broadly similar across governments of different political natures. However, it also assumes that the market factors and employers are the main factors, while politics and the government are just secondary forces.

The Apex of Regional Civilizations Essay Example | Topics and Well Written Essays - 250 words

The Apex of Regional Civilizations - Essay Example In this context, the war was not inevitable. The Chronicle of the Incans also present the views of the Incan economy and redistributive early civilization. Nevertheless, as illustrated by Cieza de Leon’s, the document is an historical narrative of the events of the Spanish conquest of Peru and the civil wars among the Spaniards. The parallelism coming forth from the Aztec and Incan (Americans) and the European (Spanish) civilization is that while one was convinced at unionizing their cultural identity, others were rocked into civil wars allowing the Europeans to conquer them. The similarities in the way Duran and de Cieza view indigenous American civilizations begin by the modes of their colonization by Spain. The civil war and lack of coordinated cultural views and hypocritical combination of Christianity and their prehispanic religions amount to some of the similarities in the two documents. In conclusion, the presence of the strong American Indian empires in the 16th century was disrupted by European civilizations and civil wars among them. This made it easy for the Europeans (such as Spain) to introduce religious wars as an excuse f conquering them. Duran and de Cieza gives an illustrative accounts of how the indigenous Americans, Aztecs and Incans, lost their

Terrorism Affecting The World Economy Essay Example | Topics and Well Written Essays - 750 words

Terrorism Affecting The World Economy - Essay Example To trigger development, it encouraged the formation of rural enterprises, liberalized foreign trade and investment, introduced education reforms, and invested heavily in industrial production. In several peak years, the GDP hit as high as 13 % and today the per capita income has quadrupled compared to what it was 15 years and if the predictions by various analysts hold true, the Chinese economy will cross that of United States in another 20 years. (Khan 2007) According to a research conducted by IMF in an attempt to find the key sources of its growth, it was found that the increase in the number of Chinese workers has been one of the major factors of its growth. At the same time capital accumulation through the growth in the overall assets of the country, new factories, manufacturing machinery and development in its communication systems have also marked its growth. According to most theoretical and empirical analysis conducted, more than 42 percent of china's growth has to do with productivity gains since 1979-94 but after 1994 capital took over as the most significant and primary source of growth. This marks an avid departure from the more traditional views on development wherein capital investment takes the lead. In most cases, economists studying Chinese Growth have faced lots of theoretical and empirical issues most of which cr... It elaborates over the link between productive factors such as capital and labour to output. This model is mostly applied to market economies but can also be used for command economies. In addition, finding from such empirically modelled data has led to the conclusion that in recent year's capital investment in goods and technology have led to increase in productivity. (A Measurement of the Contribution Made by Foreign Investment 2005) India: India has shown remarkable economic growth for the past three years of its running. For a decade, it has been registering an economic growth of 7% plus which has led to reduction in poverty by 10 %. However 60% of India's population continues to thrive on agriculture which makes a poverty alleviation a major economic channel. The fact that droughts and floods are still common in the nation, does not sit too well with the agents of economic growth. According to a hypothetical analysis that was recently conducted, one main reason behind India's economic growth has been the structural transformation that has been adopted by the national government. India's economic growth has been oft conceived as directly related to that of its performance in the service sector in particular. Its growth rate was above 11 % in 2007 and contributes to 53 % of GDP today. Investment in industrial sector has been another key component of its growth and it contributes to 29% of its GDP where as agriculture is 17 % of its economy. Manufacturing sector has emerged rapidly and has shown remarkable progress between 2005 and 2006. It grew by 12 % during this time where as communication and storage sectors grew by 16 %. (Indian Economy overview

The Apex of Regional Civilizations Essay Example | Topics and Well Written Essays - 250 words

The Apex of Regional Civilizations - Essay Example In this context, the war was not inevitable. The Chronicle of the Incans also present the views of the Incan economy and redistributive early civilization. Nevertheless, as illustrated by Cieza de Leon’s, the document is an historical narrative of the events of the Spanish conquest of Peru and the civil wars among the Spaniards. The parallelism coming forth from the Aztec and Incan (Americans) and the European (Spanish) civilization is that while one was convinced at unionizing their cultural identity, others were rocked into civil wars allowing the Europeans to conquer them. The similarities in the way Duran and de Cieza view indigenous American civilizations begin by the modes of their colonization by Spain. The civil war and lack of coordinated cultural views and hypocritical combination of Christianity and their prehispanic religions amount to some of the similarities in the two documents. In conclusion, the presence of the strong American Indian empires in the 16th century was disrupted by European civilizations and civil wars among them. This made it easy for the Europeans (such as Spain) to introduce religious wars as an excuse f conquering them. Duran and de Cieza gives an illustrative accounts of how the indigenous Americans, Aztecs and Incans, lost their

Archduke Ferdinand and Gavrilo Princip Essay Example for Free

Archduke Ferdinand and Gavrilo Princip Essay The connection between Archduke Ferdinand and that of Gavrilo Princip was that of an assassin and a victim. Though these two men had nothing in common at birth, their fates were intertwined by a series of events that led to their meeting on the fateful Sunday of June 28th, 1914. Archduke Francis Ferdinand was an Archduke of Austria-Este who was provisionally scheduled to inherit the Austro-Hungarian throne. At birth, there was no reason to think that he would be heir presumptive, but certain events happened that quickly changed this presumption. His cousin Crown Prince Rudolf committed suicide and his father relinquished his succession rights within days of the tragedy. From then on, he started being groomed for succession. He met and married Countess Sophie Chotek. Politically, the archduke advocated for sovereignty of all the ethnic groups in the empire. With Serbia, he approached it carefully believing that harsh treatment of Serbia would bring a disagreement between Austrian- Hungary and Russia . Gavrilo Princip on the other hand was an ethnic Serb born in Bosnia- Herzegovina in July, 1984. He left for Serbia in his teenage years to continue his education. While there, he joined the Black Hand secret society, a terrorist group that had mandated itself with the task of separating Bosnia-Herzegovina from the Austria-Hungarian Empire and unifying it with an independent Serbia . Senior members of Black Hand felt that Archduke Franz Ferdinand’s political plans would make attaining the independence of Serbia slow, if not impossible. It therefore followed that when they learned that the Archduke Franz Ferdinand was planning a trip to Sarajevo in June of 1914, they planned an assassination . On 28th June, 1914 Archduke Ferdinand and his wife Sophia arrived in Sarajevo. Gavrilo Princip was among the seven members of Black Hand mandated with the task of assassinating him. The seven members spaced out along the Appel Quay each having been given instructions to and kill the Archduke when his motorcade approached his position. The attempts of all seven of them failed with only one of them managing to throw a grenade that did not kill the archduke. Ferdinand and his wife proceeded to the town hall to attend their official reception. Later, as they were on their way to the hospital to see those that had been injured from the earlier incident, they came face to face with Gavrilo Princip. Princip took advantage of the situation and fired two bullets, one killing Duchess Sophia and the other one killing the Archduke. This assassination sparked a series of events that led to the First World War. References: Belfield, Richard (1966) The Assassination Business: A History of State-Sponsored Murder. Carroll Graf Publishers: New York Gilbert, Martin (1995). First World War. HarperCollins. pp. 11-12 Marshall, S. L. A. (2001). World War I. Mariner Books. p. 2-3 www. spartacus. schoolnet. co. uk/FWWprincip. htm. Accessed on 2nd April, 2009 www. imdb. com/name/nm1532728/bio. Accessed on 2nd April, 2009

History and Development of Psychology

History and Development of Psychology DEVELOPMENT OF PSYCHOLOGY The commencement of the history of psychology is difficult to determine, essentially for the reason that it is hard to found accurately what psychology is. Instead, we can simply point that psychology is the study of the mind and its  functions particularly those disturbing comportment in a given context. One way to think about the olden times of psychology is to categorize the different theorists and theories into â€Å"sections† (or schools of thought). Each section is a manner of thinking about human mind and actions that actually dominated the field for a certain epoch until a new manner of considering psychology started to control the field. THE BEGINNINGS OF PSYCHOLOGY The most primitive origins of psychology are, predictably, found in the primeval cultures of Greece, Egypt, China and India. (Oren Lahav .Origins of psychology.Available: http://psychology.learnhub.com/lesson/3833-origins-of-psychology. Last accessed 27 January 2015.) While modern psychology reveals the discipline’s rich and diverse history, the roots of psychology fluctuate considerably from present conceptions of the field. (Kendra cherry.The OriginsofPsychology.Available:http://psychology.about.com/od/historyofpsychology/a/psychistory.htm. Last accessed 27 January 2015.) From its initial beginnings, psychology has been confronted with several questions. The initial interrogation of how to describe psychology help out to establish it as a science distinct from physiology and philosophy. Further questions that psychologists have faced all through history comprise: Is psychology truly a science? Should psychology emphasis on visible behaviors, or on inner cerebral processes? What topics and issues should psychology be concerned with? Whatresearch methodsshould be used to study psychology? Psychology itself had a long history, as a topic within the fields of philosophy and physiology. The initial psychological fundamentals are deep-rooted in philosophy. While the great philosophical dissimilarity between mind and body in western believed can be originated to the Greeks, it is to the powerful work of Renà © Descartes, French mathematics, philosopher and psychologist that we owe the concept of dualism that stated that the mind and the body were two dissimilar things that interrelate to create the human experience. (History of Psychology. 123HelpMe.com. Available: http://www.123HelpMe.com/view.asp?id=69704. Last accessed 27 January 2015). Today psychology is still related with several of the fundamental philosophical enquiries that thinkers were considering many years ago such as the correlative contributions of nature vs. nurture. (Kendra cherry.The Influence of Philosophy and Physiology. Available:http://www.netplaces.com/psychology/psychology-yesterday-and-today/the-i nfluence-of-philosophy-and-physiology.htm. Last accessed 27 January 2015). So what sorts out psychology unlike from philosophy? Early philosophers have recourse to techniques such as observation and judgment while modern psychologists made use of scientific ways to investigate and derive conclusions about human notion and actions. Early physiology enquiry on the mind and actions had an outstanding influence on psychology, essentially giving rise to the application of scientific methods to the study of human mind and behavior. (Kendra cherry.The OriginsofPsychology.Available:http://psychology.about.com/od/historyofpsychology/a/psychistory.htm. Last accessed 27 January 2015.) Psychology emerges as a separate discipline. Psychology took so long to emanate as a research-based field because it required time to mingle. Interpretating behavior, thoughts and emotions is challenging, which may possibly demonstrate why it was basically disregarded between ancient Greek times and the 16th century. (Saul McLeod. (2008). Psychology as a Science. Available: http://www.simplypsychology.org/science-psychology.html. Last accessed 27 January 2015.) So how psychology did became an independent field? Wundtian Psychology and Structuralism Psychology as a research-based subject began to spring in the 1800’s. (Saul McLeod. (2008). Psychology as a Science. Available: http://www.simplypsychology.org/science-psychology.html. Last accessed 27 January 2015.) Wilhelm Wundt (1832-1920) is recognized with founding the first psychology laboratory in Leipzig, Germany in 1879. Generally reckoned as the father of psychology, we might credit the founding to Wundt in 1874 when he composed his first textbook issued as â€Å"Principles of Physiological Psychology†. (â€Å"Early Frameworks: Structuralism and Functionalism.†(20 Sep 2014). Boundless Psychology. Available:https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/introduction-to-psychology-1/history-of-psychology-23/early-frameworks-structuralism-and-functionalism-111-12648/ Last accessed 28 January 2015). Wundt actually made use of scientific methodologies especially his primary method of research which was â€Å"introspection†. (History of Psychology. 123HelpMe.com. Available: http://www.123HelpMe.com/view.asp?id=69704. Last accessed 27 January 2015). Wundt was concerned in studying the mind and conscious involvement. He maintained the point that the investigation of mindful thoughts would be the key to know the mind. His method to the enquiry of the mind was revolutionary in that it was founded on methodical and rigorous reflection, setting the groundwork for modern psychological research. †. (â€Å"Early Frameworks: Structuralism and Functionalism.†(20 Sep 2014). Boundless Psychology.Available:https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/introduction-to-psychology-1/history-of-psychology-23/early-frameworks-structuralism-and-functionalism-111-12648/ Last accessed 27 January 2015). Introspection was a practice used by investigators to term and examine their personal internal thoughts and emotions throughout a research experience (From R. Eric Landrum. Brief History of Psychology. Available: http://personal.psu.edu/faculty/a/c/acp103/PSYCH105/brief_history.htm. Department of Psychology. Boise State University. Last accessed 28 January 2015). Introspection subsisted for a few times and is still used today in present neuroscience study; nevertheless many scientists slate the use of introspection for its lack of experimental approach and fairness. (Kendra cherry.The Influence of Philosophy and Physiology. Available:http://www.netplaces.com/psychology/psychology-yesterday-and-today/the-influence-of-philosophy-and-physiology.htm. Last accessed 28 January 2015). Structuralism Becomes Psychology’s First School of Thought Structuralism emerged from Wundts concepts. Edward B. Titchener, an English instructor who was an apprentice under Wundt’s management, elaborated upon Wundts ideas and used them to establish the theory of structuralism, which aim to comprehend the mind as the â€Å"sum of varying underlying parts†. (â€Å"Early Frameworks: Structuralism and Functionalism.†(20 Sep 2014). Boundless Psychology.Available:https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/introduction-to-psychology-1/history-of-psychology-23/early-frameworks-structuralism-and-functionalism-111-12648/ Last accessed 28 January 2015). The ultimate objective was to understand the brainpower. He assumed that if the rudimentary constituents of the mind could be demarcated and classified, then the structure of mental processes and higher thinking could be resoluted. (â€Å"Early Frameworks: Structuralism and Functionalism.†(20 Sep 2014). Boundless Psychology.Available:https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/introduction-to-psychology-1/history-of-psychology-23/early-frameworks-structuralism-and-functionalism-111-12648/ Last accessed 28 January 2015). Using Wundt’s primary method that is introspection, however with strict guidelines, Titchener’s volunteers would try to crack down their responses and reactions to the most root feelings and discernments. (Kendra Cherry. ().The Origins of Psychology.Available: http://psychology.about.com/od/historyofpsychology/a/psychistory.htm. Last accessed 28 January 2015.) Structuralism was criticized because its subject of scrutiny—the conscious experience—was not simply studied with skillful experimentation. Its reliance on introspection, despite Titcheners strict rules, was disapproved for its deficiency in authenticity. Judges claimed that self-reflection is not viable, and that introspection can provide diverse results depending on the subject. (â€Å"Early Frameworks: Structuralism and Functionalism.†(20 Sep 2014). Boundless Psychology.Available:https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/introduction-to-psychology-1/history-of-psychology-23/early-frameworks-structuralism-and-functionalism-111-12648/ Last accessed 28 January 2015). Even though the quest of structuralism mostly died with Titchener (1867-1927), he supplied a solid system of psychology which would well along be the matter and center of major alterations in psychology, resulting in a substitute approach to psychology: functionalism. (â€Å"Early Frameworks: Structuralism and Functionalism.†(20 Sep 2014). Boundless Psychology.Available:https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/introduction-to-psychology-1/history-of-psychology-23/early-frameworks-structuralism-and-functionalism-111-12648/ Last accessed 28 January 2015). Functionalism Functionalism is of great significance to the history of American psychology, for the reason that it is a system of psychology that is exclusively American. Wundtian psychology and structuralism one and the other have their origins in Germany, but functionalism is an American product. (From R. Eric Landrum. Brief History of Psychology. Available: http://personal.psu.edu/faculty/a/c/acp103/PSYCH105/brief_history.htm. Department of Psychology. Boise State University. Last accessed 28 January 2015). The Functionalism of William James American psychologist William James emerges in the mid- to late-1800s. While structuralism centered  (synonymize)on discovering the structure of consciousness and how its contents are organized and stored, functionalists were more interested in how the mind worked, what mental processes accomplish, and what role consciousness plays in our behavior. As you can see, these are two strikingly different approaches. The functionalist wanted to know how and why the mind works (as opposed to how is it structured).

Proposing Windsor Boys and Girls Group Learning of Dance and Drama :: essays research papers

I am a six form council representative and I proposed an idea, discussed at length and agreed by everyone at the meeting and also by the students that study dance and drama that Windsor boys and Windsor girls should join together to study these lessons. This arrangement would cover a two-year period- AS and A2 level study. It would only apply to these two subjects however it could work well in other subject areas too. I do understand that some concerns will arise but I hope I can overcome any problems that do come up and hopefully I can persuade you in to this arrangement. I have taken this idea to the head of the department in the boy’s school and also the head of the department in our school. Both departments are very supportive of the idea and think that it would be very helpful in making lessons and productions more realistic. This would be a joint project, the drama and dance teachers will be working as a team and each teacher will mark a joint assessment however, each teacher will be responsible for their own pupil. Having thought this arrangement and talking it through with everyone concerned the boy’s school have offered to us the use of their facilities and equipment as they are much superior to ours. We have also decided that as the boy’s school is in walking distance, we would be prepared to walk to the school to complete our lesson, we would be in groups so it would be safe and also the dance and drama teachers would accompany us in order to reduce cost and facilities. Both schools are prepared to co operate with this p roject. We are also strong willed about scheduling to leave our school in our lunch time and start walking to the boy’s school in order for us to be able to arrive at the correct time so we will be able to begin and finish our lesson on time without having to over run or to make up for lost time because of lateness. Everyone concerned in this idea agrees that this would be a fantastic opportunity as the outcome consists of many advantages. Joining both schools’ together and having mixed gender lessons would mean that the productions and lessons would be more realistic, it would improve the performance to a high standard as everyone would be playing realistic and right roles.

Airport Security Essay -- Safety Airlines Terrorism Papers

Airport Security On September 11, 2001, twenty Arab men boarded four different airplanes with the intent of attacking our country. They boarded the planes with the intent of causing tremendous damage to New York City and Washington, D.C. Two planes crashed into each tower of the World Trade Center, one plane crashed into the Pentagon, and the last plane crashed into a Pennsylvanian field. These twenty men cut short over 3000 lives. The innocent people that died had no need to have their lives taken in the way that they were. However, they lost their lives because they were American, and to the terrorists, they stood for certain principles. How were these terrorists allowed to board these planes with the weapons that they used for the take over? There is an easy answer to that question: airport security was virtually nonexistent. Anyone could be in the terminal. Friends and family could be with the passenger up to the time that the passenger went through the gate. However, since that fateful day, security has been tighter at the airports. Now, before passengers board a plane, they have to go through an x-ray machine and a metal detector before entering the terminal. Sometimes they have to go through random searches at the plane's gate. One question raised from the tighter security measures is whether these security measures invade people's personal rights. Airport security has changed since September 11, but this change is not always a good thing. One of the major changes that has taken place in airport security is more searches are being done. As a result of increasing the number of searches taken place, more people have their privacy rights violated. Another result of the increase of airport security is that less peopl... ...y.html Simon, Harvey. "Homeland Security and Defense." Aviation Week. n.d. 5 June 2002 Swenson, Dan. Personal interview. 23 October 2002 Sperry, Paul. "Know Your Rights at Airport Checkpoints." Worldnetdaily. 9 January 2002, 15 Oct. 2002 http://www.worldnetdaily.com/news/printer-friendly.asp?ARTICLE_ID=25974 "Suggestions for Reducing Security Related Threats." Airsafe. 22 October 2001, 16 September 2002 http://www.airsafe.com/events/war/moresafe.htm The Thompson Chain-Reference Bible: The NIV Version. Indianapolis, Indiana: B.B. Kirkbridge Bible CO., INC., 1990 "Travelers' Blues." Free-Market Net. n.d.15 October 2002 http://www.free-market.net/spotlight/airtravel/organizations/ "Women Travelers Complain of 'Busy Hands' Among Airport Guards." Startribune. 25 November 2002, 15 Oct. 2002 http://www.startribune.com/stories/1631/850064.html

Solution Manual for Fluid Mech Cengel Book

Chapter 6 Momentum Analysis of Flow Systems Chapter 6 MOMENTUM ANALYSIS OF FLOW SYSTEMS Newton’s Laws and Conservation of Momentum 6-1C Newton’s first law states that â€Å"a body at rest remains at rest, and a body in motion remains in motion at the same velocity in a straight path when the net force acting on it is zero. † Therefore, a body tends to preserve its state or inertia. Newton’s second law states that â€Å"the acceleration of a body is proportional to the net force acting on it and is inversely proportional to its mass. Newton’s third law states â€Å"when a body exerts a force on a second body, the second body exerts an equal and opposite force on the first. † r 6-2C Since momentum ( mV ) is the product of a vector (velocity) and a scalar (mass), momentum must be a vector that points in the same direction as the velocity vector. 6-3C The conservation of momentum principle is expressed as â€Å"the momentum of a system remains constant when the net force acting on it is zero, and thus the momentum of such systems is conserved†.The momentum of a body remains constant if the net force acting on it is zero. 6-4C Newton’s second law of motion, also called the angular momentum equation, is expressed as â€Å"the rate of change of the angular momentum of a body is equal to the net torque acting it. † For a non-rigid body with zero net torque, the angular momentum remains constant, but the angular velocity changes in accordance with I? = constant where I is the moment of inertia of the body. 6-5C No.Two rigid bodies having the same mass and angular speed will have different angular momentums unless they also have the same moment of inertia I. Linear Momentum Equation 6-6C The relationship between the time rates of change of an extensive property for a system and for a control volume is expressed by the Reynolds transport theorem, which provides the link between the r system and control volume concepts. The linear momentum equation is obtained by setting b = V and thus r B = mV in the Reynolds transport theorem. -7C The forces acting on the control volume consist of body forces that act throughout the entire body of the control volume (such as gravity, electric, and magnetic forces) and surface forces that act on the control surface (such as the pressure forces and reaction forces at points of contact). The net force acting on a control volume is the sum of all body and surface forces. Fluid weight is a body force, and pressure is a surface force (acting per unit area). -8C All of these surface forces arise as the control volume is isolated from its surroundings for analysis, and the effect of any detached object is accounted for by a force at that location. We can minimize the number of surface forces exposed by choosing the control volume such that the forces that we are not interested in remain internal, and thus they do not complicate the analysis. A well-chosen cont rol volume exposes only the forces that are to be determined (such as reaction forces) and a minimum number of other forces. 6-9C The momentum-flux correction factor ? nables us to express the momentum flux in terms of the r r r r & ? V (V ? n )dAc = ? mV avg . The value of ? is unity for uniform mass flow rate and mean flow velocity as ? Ac flow, such as a jet flow, nearly unity for turbulent flow (between 1. 01 and 1. 04), but about 1. 3 for laminar flow. So it should be considered in laminar flow. 6-1 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission.Chapter 6 Momentum Analysis of Flow Systems 6-10C The momentum equation for steady one-dimensional flow for the case of no external forces is r r r & & F= ? mV ? ? mV ? ? out ? in where the left hand side is the net force acting on the control volume, and first term on the right hand side is the incoming momentum flux and the second term is the outgoing momentum flux by mass. 6-11C In the application of the momentum equation, we can disregard the atmospheric pressure and work with gage pressures only since the atmospheric pressure acts in all directions, and its effect cancels out in every direction. -12C The fireman who holds the hose backwards so that the water makes a U-turn before being discharged will experience a greater reaction force since the numerical values of momentum fluxes across the nozzle are added in this case instead of being subtracted. 6-13C No, V is not the upper limit to the rocket’s ultimate velocity. Without friction the rocket velocity will continue to increase as more gas outlets the nozzle. 6-14C A helicopter hovers because the strong downdraft of air, caused by the overhead propeller blades, manifests a momentum in the air stream.This momentum must be countered by the helicopter lift force. 6-15C As the air density decreases, it requires more energy for a helicopter to hover, because more air must be forced into the downdraft by the helicopter blades to provide the same lift force. Therefore, it takes more power for a helicopter to hover on the top of a high mountain than it does at sea level. 6-16C In winter the air is generally colder, and thus denser. Therefore, less air must be driven by the blades to provide the same helicopter lift, requiring less power. 6-2 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc.Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-17C The force required to hold the plate against the horizontal water stream will increase by a factor of 4 when the velocity is doubled since & F = mV = ( ? AV )V = ? AV 2 and thus the force is proportional to the square of the velocity. 6-18C The accele ration will not be constant since the force is not constant. The impulse force exerted by & water on the plate is F = mV = ( ? AV )V = ?AV 2 , where V is the relative velocity between the water and the plate, which is moving. The plate acceleration will be a = F/m. But as the plate begins to move, V decreases, so the acceleration must also decrease. 6-19C The maximum velocity possible for the plate is the velocity of the water jet. As long as the plate is moving slower than the jet, the water will exert a force on the plate, which will cause it to accelerate, until terminal jet velocity is reached. 6-20 It is to be shown that the force exerted by a liquid jet of velocity V on a stationary nozzle is & proportional to V2, or alternatively, to m 2 . Assumptions 1 The flow is steady and incompressible. 2 The nozzle is given to be stationary. 3 The nozzle involves a 90 ° turn and thus the incoming and outgoing flow streams are normal to each other. 4 The water is discharged to the atmo sphere, and thus the gage pressure at the outlet is zero. Analysis We take the nozzle as the control volume, and the flow direction at the outlet as the x axis. Note that the nozzle makes a 90 ° turn, and thus it does not contribute to any pressure force or momentum flux & term at the inlet in the x direction. Noting that m = ?AV where A is the nozzle outlet area and V is the average nozzle outlet velocity, the momentum equation for steady one-dimensional flow in the x direction reduces to r r r & & & & F= ? mV ? ? mV > FRx = ? m out V out = ? mV ? ? out ? in where FRx is the reaction force on the nozzle due to liquid jet at the nozzle outlet. Then, & m = ? AV & > FRx = ? mV = AVV = AV 2 & & or FRx = ? mV = ? m & & m m2 =? ?A ? A Therefore, the force exerted by a liquid jet of velocity V on this & stationary nozzle is proportional to V2, or alternatively, to m 2 . Liquid Nozzle V FR 6-3 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc.Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-21 A water jet of velocity V impinges on a plate moving toward the water jet with velocity ? V. The force required to move the plate towards the jet is to be determined in terms of F acting on the stationary plate. Assumptions 1 The flow is steady and incompressible. 2 The plate is vertical and the jet is normal to plate. 3 The pressure on both sides of the plate is atmospheric pressure (and thus its effect cancels out). Fiction during motion is negligible. 5 There is no acceleration of the plate. 6 The water splashes off the sides of the plate in a plane normal to the jet. 6 Jet flow is nearly uniform and thus the effect of the momentum-flux correction factor is negligible, ? ? 1. Analysis We take the plate as the control volume. The relative velocity between the plate and the jet is V when the plate is st ationary, and 1. 5V when the plate is moving with a velocity ? V towards the plate. Then the momentum equation for steady one-dimensional flow in the horizontal direction reduces to r r r & & & & F= ? mV ? ? mV > ? FR = ? mi Vi > FR = miVi ? out ? in Stationary plate: ( Vi = V and Moving plate: ( Vi = 1. 5V and & mi = ? AVi = ? AV ) > FR = ? AV 2 = F & mi = ? AVi = ? A(1. 5V ) ) > FR = ? A(1. 5V ) 2 = 2. 25 ? AV 2 = 2. 25 F Therefore, the force required to hold the plate stationary against the oncoming water jet becomes 2. 25 times when the jet velocity becomes 1. 5 times. Discussion Note that when the plate is stationary, V is also the jet velocity. But if the plate moves toward the stream with velocity ? V, then the relative velocity is 1. 5V, and the amount of mass striking the plate (and falling off its sides) per unit time also increases by 50%. 1/2V VWaterjet 6-4 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-22 A 90 ° elbow deflects water upwards and discharges it to the atmosphere at a specified rate. The gage pressure at the inlet of the elbow and the anchoring force needed to hold the elbow in place are to be determined. v Assumptions 1 The flow is steady, frictionless, incompressible, and irrotational (so that the Bernoulli equation is applicable). The weight of the elbow and the water in it is negligible. 3 The water is discharged to the atmosphere, and thus the gage pressure at the outlet is zero. 4 The momentum-flux correction factor for each inlet and outlet is given to be ? = 1. 03. Properties We take the density of water to be 1000 kg/m3. Analysis (a) We take the elbow as the control volume, and designate the entrance by 1 and the outlet by 2. We also designate the horizontal coordinate by x (with the direction of flow as being the positive direction) and the vertical coordinate by z.The continuity equation for this one-inlet one-outlet steady flow system is & & & & m1 = m 2 = m = 30 kg/s. Noting that m = ? AV , the mean inlet and outlet velocities of water are & & 25 kg/s m m = = = 3. 18 m/s 2 ? A ? (? D / 4) (1000 kg/m 3 )[? (0. 1 m) 2 / 4] Noting that V1 = V2 and P2 = Patm, the Bernoulli equation for a streamline going through the center of the reducing elbow is expressed as V1 = V 2 = V = P V12 P V2 1 + + z1 = 2 + 2 + z2 > P ? P2 = ? g ( z2 ? z1 ) > P , gage = ? g ( z2 ? z1 ) 1 1 ? g 2 g ? g 2 g Substituting, ? ? 1 kN 2 ? P , gage = (1000 kg/m3 )(9. 81 m/s 2 )(0. 35 m)? 1 ? 1000 kg ? /s2 ? = 3. 434 kN/m = 3. 434 kPa ? ? r r r & & (b) The momentum equation for steady one-dimensional flow is F= ? mV ? ? mV . We let the x- ? ? out ? in and z- components of the anchoring force of the elbow be FRx and FRz, and assume them to be in the positive directions. We also use gage pressures to avoid dealing with the atmospheric pressure which acts on all surfaces. Then the momentum equations along the x and y axes become & & FRx + P1,gage A1 = 0 ? ?m(+V1 ) = ? ?mV & & FRz = ? m(+V 2 ) = ? mV z x FRz 2 35 cm Solving for FRx and FRz, and substituting the given values, & FRx = ? ?mV ? P1, gage A1 ? N = ? 1. 03(25 kg/s)(3. 18 m/s)? ? 1 kg ? m/s 2 ? = ? 109 N ? ? ? (3434 N/m 2 )[? (0. 1 m) 2 / 4] ? ? ? ? = 81. 9 N ? ? FRy FRx = tan -1 Water 25 kg/s FRx 1 ? 1N & FRy = ? mV = 1. 03(25 kg/s)(3. 18 m/s)? ? 1 kg ? m/s 2 ? and 2 2 FR = FRx + FRy = (? 109) 2 + 81. 9 2 = 136 N, ? = tan -1 81. 9 = ? 37 ° = 143 ° ? 109 Discussion Note that the magnitude of the anchoring force is 136 N, and its line of action makes 143 ° from the positive x direction. Also, a negative value for FRx indicates the assumed direction is wrong, and should be reversed. 6-5 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc.Limited distribution permitted only to teachers and educators for course preparatio n. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-23 An 180 ° elbow forces the flow to make a U-turn and discharges it to the atmosphere at a specified rate. The gage pressure at the inlet of the elbow and the anchoring force needed to hold the elbow in place are to be determined. v Assumptions 1 The flow is steady, frictionless, one-dimensional, incompressible, and irrotational (so that the Bernoulli equation is applicable). The weight of the elbow and the water in it is negligible. 3 The water is discharged to the atmosphere, and thus the gage pressure at the outlet is zero. 4 The momentumflux correction factor for each inlet and outlet is given to be ? = 1. 03. Properties We take the density of water to be 1000 kg/m3. Analysis (a) We take the elbow as the control volume, and designate the entrance by 1 and the outlet by 2. We also designate the horizontal coordinate by x (with the direction of flow as b eing the positive direction) and the vertical coordinate by z.The continuity equation for this one-inlet one-outlet steady flow system is & & & & m1 = m 2 = m = 30 kg/s. Noting that m = ? AV , the mean inlet and outlet velocities of water are & & 25 kg/s m m = = = 3. 18 m/s 2 ? A ? (? D / 4) (1000 kg/m 3 )[? (0. 1 m) 2 / 4] Noting that V1 = V2 and P2 = Patm, the Bernoulli equation for a streamline going through the center of the reducing elbow is expressed as V1 = V 2 = V = P V12 P V2 1 + + z1 = 2 + 2 + z2 > P ? P2 = ? g ( z2 ? z1 ) > P , gage = ? g ( z2 ? z1 ) 1 1 ? g 2 g ? g 2 g Substituting, ? ? 1 kN 2 ? P , gage = (1000 kg/m3 )(9. 81 m/s2 )(0. 70 m)? 1 ? 1000 kg ? m/s2 ? 6. 867 kN/m = 6. 867 kPa ? ? r r r & & (b) The momentum equation for steady one-dimensional flow is F= ? mV ? ? mV . We let the x- ? ? out ? in and z- components of the anchoring force of the elbow be FRx and FRz, and assume them to be in the positive directions. We also use gage pressures to avoid dealing with the atmospheric pressure which acts on all surfaces. Then the momentum equations along the x and z axes become & & & FRx + P1,gage A1 = ? m(? V 2 ) ? ? m(+V1 ) = ? 2 ? mV FRz = 0 Solving for FRx and substituting the given values, & FRx = ? 2 ? mV ? P1, gage A1 ? 1N = ? 2 ? 1. 03(25 kg/s)(3. 18 m/s)? 1 kg ? m/s 2 ? = ? 218 N ? ? ? (6867 N/m 2 )[? (0. 1 m) 2 / 4] ? ? 2 z x FRz Water 25 kg/s 35 cm and FR = FRx = – 218 N since the y-component of the anchoring force is zero. Therefore, the anchoring force has a magnitude of 218 N and it acts in the negative x direction. Discussion Note that a negative value for FRx indicates the assumed direction is wrong, and should be reversed. FRx 1 6-6 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission.Chapter 6 Momentum Analysis of Flow Systems 6-24E A horizontal water j et strikes a vertical stationary plate normally at a specified velocity. For a given anchoring force needed to hold the plate in place, the flow rate of water is to be determined. Assumptions 1 The flow is steady and incompressible. 2 The water splatters off the sides of the plate in a plane normal to the jet. 3 The water jet is exposed to the atmosphere, and thus the pressure of the water jet and the splattered water is the atmospheric pressure which is disregarded since it acts on the entire control surface. The vertical forces and momentum fluxes are not considered since they have no effect on the horizontal reaction force. 5 Jet flow is nearly uniform and thus the effect of the momentum-flux correction factor is negligible, ? ? 1. Properties We take the density of water to be 62. 4 lbm/ft3. Analysis We take the plate as the control volume such that it contains the entire plate and cuts through the water jet and the support bar normally, and the direction of flow as the positive direction of x axis. The momentum equation for steady one-dimensional flow in the x (flow) direction reduces in this case o r r r & & & & F= ? mV ? ? mV > ? FRx = ? mV1 > FR = mV1 ? ? out ? in We note that the reaction force acts in the opposite direction to flow, and we should not forget the negative & sign for forces and velocities in the negative x-direction. Solving for m and substituting the given values, & m= FRx 350 lbf = V1 30 ft/s ? 32. 2 lbm ? ft/s 2 ? ? 1 lbf ? ? ? = 376 lbm/s ? ? Then the volume flow rate becomes V& = & m ? = 376 lbm/s 62. 4 lbm/ft 3 = 6. 02 ft 3 /s Therefore, the volume flow rate of water under stated assumptions must be 6. 02 ft3/s.Discussion In reality, some water will be scattered back, and this will add to the reaction force of water. The flow rate in that case will be less. m 1 FRx = 350 lbf Waterjet 6-7 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparati on. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-25 A reducing elbow deflects water upwards and discharges it to the atmosphere at a specified rate.The anchoring force needed to hold the elbow in place is to be determined. v Assumptions 1 The flow is steady, frictionless, one-dimensional, incompressible, and irrotational (so that the Bernoulli equation is applicable). 2 The weight of the elbow and the water in it is considered. 3 The water is discharged to the atmosphere, and thus the gage pressure at the outlet is zero. 4 The momentumflux correction factor for each inlet and outlet is given to be ? = 1. 03. Properties We take the density of water to be 1000 kg/m3. Analysis The weight of the elbow and the water in it is W = mg = (50 kg)(9. 1 m/s 2 ) = 490. 5 N = 0. 4905 kN We take the elbow as the control volume, and designate the entrance by 1 and the outlet by 2. We also designate the horizontal coordina te by x (with the direction of flow as being the positive direction) and the vertical coordinate by z. The continuity equation for this one-inlet one-outlet steady flow system is & & & & m1 = m 2 = m = 30 kg/s. Noting that m = ? AV , the inlet and outlet velocities of water are & 30 kg/s m V1 = = = 2. 0 m/s ? A1 (1000 kg/m 3 )(0. 0150 m 2 ) & 30 kg/s m V2 = = = 12 m/s ? A2 (1000 kg/m 3 )(0. 025 m 2 ) Taking the center of the inlet cross section as the reference level (z1 = 0) and noting that P2 = Patm, the Bernoulli equation for a streamline going through the center of the reducing elbow is expressed as ? V 2 ? V12 ? ? V22 ? V12 ? P V12 P V2 1 ? ? ? + + z1 = 2 + 2 + z2 > P ? P2 = ? g ? 2 1 1 ? 2 g + z2 ? z1 ? > P , gage = ? g ? 2 g + z2 ? ?g 2 g ? g 2 g ? ? ? ? Substituting, ? (12 m/s) 2 ? (2 m/s) 2 ? 1 kN ? = 73. 9 kN/m 2 = 73. 9 kPa P , gage = (1000 kg/m3 )(9. 81 m/s 2 )? + 0. 4 1 2 ? 1000 kg ? m/s 2 ? 2(9. 81 m/s ) ? ? The momentum equation for steady one-dimensional flow is & & ? F = ? mV ? ? ? mV . We let the x- and out in r r r z- components of the anchoring force of the elbow be FRx and FRz, and assume them to be in the positive directions. We also use gage pressures to avoid dealing with the atmospheric pressure which acts on all surfaces. Then the momentum equations along the x and z axes become & & & FRx + P1,gage A1 = ? mV 2 cos ? ? ? mV1 and FRz ? W = ? mV 2 sin ? 2 25 cm2 Solving for FRx and FRz, and substituting the given values, & FRx = ? m(V 2 cos ? ? V1 ) ? P1, gage A1 ? 1 kN = 1. 03(30 kg/s)[(12cos45 ° – 2) m/s]? ? 1000 kg ? m/s 2 ? ? (73. 9 kN/m 2 )(0. 0150 m 2 ) = ? 0. 908 kN ? ? ? Water 30 kg/s 45 ° FRz FRx 150 m2 W 1 ? ? 1 kN ? & FRz = ? mV 2 sin ? + W = 1. 03(30 kg/s)(12sin45 ° m/s)? ? 1000 kg ? m/s 2 ? + 0. 4905 kN = 0. 753 kN ? ? 0. 753 2 2 2 2 -1 FRz FR = FRx + FRz = (? 0. 908) + (0. 753) = 1. 18 kN, ? = tan = tan -1 = ? 39. 7 ° FRx ? 0. 908 Discussion Note that the magnitude of the anchoring force is 1. 18 kN, and its line of action makes –39. 7 ° from +x direction. Negative value for FRx indicates the assumed direction is wrong. 6-8 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation.If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-26 A reducing elbow deflects water upwards and discharges it to the atmosphere at a specified rate. The anchoring force needed to hold the elbow in place is to be determined. v Assumptions 1 The flow is steady, frictionless, one-dimensional, incompressible, and irrotational (so that the Bernoulli equation is applicable). 2 The weight of the elbow and the water in it is considered. 3 The water is discharged to the atmosphere, and thus the gage pressure at the outlet is zero. The momentumflux correction factor for each inlet and outlet is given to be ? = 1. 03. Properties We take the densi ty of water to be 1000 kg/m3. Analysis The weight of the elbow and the water in it is W = mg = (50 kg)(9. 81 m/s 2 ) = 490. 5 N = 0. 4905 kN We take the elbow as the control volume, and designate the entrance by 1 and the outlet by 2. We also designate the horizontal coordinate by x (with the direction of flow as being the positive direction) and the vertical coordinate by z. The continuity equation for this one-inlet one-outlet steady flow system is & & & & m1 = m 2 = m = 30 kg/s. Noting that m = ?AV , the inlet and outlet velocities of water are & 30 kg/s m = = 2. 0 m/s V1 = ? A1 (1000 kg/m 3 )(0. 0150 m 2 ) & 30 kg/s m V2 = = = 12 m/s ? A2 (1000 kg/m 3 )(0. 0025 m 2 ) Taking the center of the inlet cross section as the reference level (z1 = 0) and noting that P2 = Patm, the Bernoulli equation for a streamline going through the center of the reducing elbow is expressed as ? V 2 ? V12 ? ? V22 ? V12 ? P V12 P V2 1 ? ? ? + + z1 = 2 + 2 + z2 > P ? P2 = ? g ? 2 1 1 ? 2 g + z2 ? z1 ? > P , gage = ? g ? 2 g + z2 ? ?g 2 g ? g 2 g ? ? ? ? or, P , gage = (1000 kg/m3 )(9. 81 m/s2 )? 1 ? ? ? (12 m/s)2 ? (2 m/s)2 2(9. 81 m/s ) ? 1 kN ? = 73. 9 kN/m 2 = 73. 9 kPa + 0. 4 1000 kg ? m/s 2 ? ? The momentum equation for steady one-dimensional flow is & & ? F = ? ?mV ? ? ? mV . We let the xout in r r r and y- components of the anchoring force of the elbow be FRx and FRz, and assume them to be in the positive directions. We also use gage pressures to avoid dealing with the atmospheric pressure which acts on all surfaces. Then the momentum equations along the x and z axes become & & FRx + P1,gage A1 = ? mV 2 cos ? ? ? mV1 and & FRy ? W = ? mV 2 sin ? Solving for FRx and FRz, and substituting the given values, & FRx = ? m(V 2 cos ? V1 ) ? P1, gage A1 ? 1 kN = 1. 03(30 kg/s)[(12cos110 ° – 2) m/s]? ? 1000 kg ? m/s 2 ? FRz ? ? ? (73. 9 kN/m 2 )(0. 0150 m 2 ) = ? 1. 297 kN ? ? ? ? 1 kN ? + 0. 4905 kN = 0. 8389 kN & = ? mV 2 sin ? + W = 1. 03(30 kg/s)(12sin110 ° m/s)? 2 ? ? 1000 kg ? m/s ? ? 2 25 cm2 110 ° 2 2 FR = FRx + FRz = (? 1. 297) 2 + 0. 8389 2 = 1. 54 kN and FRz 0. 8389 = tan -1 = ? 32. 9 ° FRx ? 1. 297 Discussion Note that the magnitude of the anchoring force is 1. 54 kN, and its line of action makes –32. 9 ° from +x direction. Negative value for FRx indicates assumed direction is wrong, and should be reversed. ? = tan -1 FRz FRx Water 1 30 kg/s 50 m2 W 6-9 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-27 Water accelerated by a nozzle strikes the back surface of a cart moving horizontally at a constant velocity. The braking force and the power wasted by the brakes are to be determined. . Assumptions 1 The flow is steady and incompressible. 2 The water splatters off the sides of the plate in all direction s in the plane of the back surface. The water jet is exposed to the atmosphere, and thus the pressure of the water jet and the splattered water is the atmospheric pressure which is disregarded since it acts on all surfaces. 4 Fiction during motion is negligible. 5 There is no acceleration of the cart. 7 The motions of the water jet and the cart are horizontal. 6 Jet flow is nearly uniform and thus the effect of the momentum-flux correction factor is negligible, ? ? 1. Analysis We take the cart as the control volume, and the direction of flow as the positive direction of x axis. The relative velocity between the cart and the jet is V r = V jet ?Vcart = 15 ? 10 = 10 m/s 15 m/s 5 m/s Therefore, we can assume the cart to be stationary and the jet to move Waterjet with a velocity of 10 m/s. The momentum equation for steady onedimensional flow in the x (flow) direction reduces in this case to r r r & & & & F= ? mV ? ? mV > FRx = ? mi Vi > Fbrake = ? mV r FRx ? ? out ? in We note that the brake force acts in the opposite direction to flow, and we should not forget the negative sign for forces and velocities in the negative x-direction. Substituting the given values, ? 1N & Fbrake = ? mV r = ? (25 kg/s)(+10 m/s)? ? 1 kg ? m/s 2 ? ? ? = ? 250 N ? ?The negative sign indicates that the braking force acts in the opposite direction to motion, as expected. Noting that work is force times distance and the distance traveled by the cart per unit time is the cart velocity, the power wasted by the brakes is 1 kW ? ? & W = FbrakeV cart = (250 N)(5 m/s)? ? = 1. 25 kW ? 1000 N ? m/s ? Discussion Note that the power wasted is equivalent to the maximum power that can be generated as the cart velocity is maintained constant. 6-10 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation.If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Fl ow Systems 6-28 Water accelerated by a nozzle strikes the back surface of a cart moving horizontally. The acceleration of the cart if the brakes fail is to be determined. Analysis The braking force was determined in previous problem to be 250 N. When the brakes fail, this force will propel the cart forward, and the accelerating will be a= F 250 N ? 1 kg ? m/s 2 ? = m cart 300 kg ? 1N ? ? ? = 0. 833 m/s 2 ? ? Discussion This is the acceleration at the moment the brakes fail.The acceleration will decrease as the relative velocity between the water jet and the cart (and thus the force) decreases. 5 m/s 15 m/s 300 kg Waterjet FRx 6-11 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-29E A water jet hits a stationary splitter, such that half of the flow is diverted up ward at 45 °, and the other half is directed down.The force required to hold the splitter in place is to be determined. vEES Assumptions 1 The flow is steady and incompressible. 2 The water jet is exposed to the atmosphere, and thus the pressure of the water jet before and after the split is the atmospheric pressure which is disregarded since it acts on all surfaces. 3 The gravitational effects are disregarded. 4 Jet flow is nearly uniform and thus the effect of the momentum-flux correction factor is negligible, ? ? 1. Properties We take the density of water to be 62. 4 lbm/ft3. Analysis The mass flow rate of water jet is & & m = ? V = (62. lbm/ft 3 )(100 ft 3 /s) = 6240 lbm/s We take the splitting section of water jet, including the splitter as the control volume, and designate the entrance by 1 and the outlet of either arm by 2 (both arms have the same velocity and mass flow rate). We also designate the horizontal coordinate by x with the direction of flow as being the positive direction and the vertical coordinate by z. r r r & & The momentum equation for steady one-dimensional flow is F= ? mV ? ? mV . We let ? ? out ? in the x- and y- components of the anchoring force of the splitter be FRx and FRz, and assume them to be in the & & positive directions.Noting that V2 = V1 = V and m 2 = 1 m , the momentum equations along the x and z 2 axes become & & & FRx = 2( 1 m)V 2 cos ? ? mV1 = mV (cos ? ? 1) 2 & & FRz = 1 m(+V 2 sin ? ) + 1 m(? V 2 sin ? ) ? 0 = 0 2 2 Substituting the given values, 1 lbf ? ? FRx = (6240 lbm/s)(20 ft/s)(cos45 ° – 1)? ? = ? 1135 lbf 32. 2 lbm ? ft/s 2 ? ? FRz = 0 The negative value for FRx indicates the assumed direction is wrong, and should be reversed. Therefore, a force of 1135 lbf must be applied to the splitter in the opposite direction to flow to hold it in place. No holding force is necessary in the vertical direction.This can also be concluded from the symmetry. Discussion In reality, the gravitational effects will cau se the upper stream to slow down and the lower stream to speed up after the split. But for short distances, these effects are indeed negligible. 20 ft/s 100 ft/s FRz 45 ° 45 ° FRx 6-12 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-30E Problem 6-29E is reconsidered.The effect of splitter angle on the force exerted on the splitter as the half splitter angle varies from 0 to 180 ° in increments of 10 ° is to be investigated. g=32. 2 â€Å"ft/s2† rho=62. 4 â€Å"lbm/ft3† V_dot=100 â€Å"ft3/s† V=20 â€Å"ft/s† m_dot=rho*V_dot F_R=-m_dot*V*(cos(theta)-1)/g â€Å"lbf† ?,  ° 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 8000 7000 6000 5000 & m , lbm/s 6240 6240 6240 6240 6240 6240 6240 6240 6240 6240 624 0 6240 6240 6240 6240 6240 6240 6240 6240 FR, lbf 0 59 234 519 907 1384 1938 2550 3203 3876 4549 5201 5814 6367 6845 7232 7518 7693 7752 FR, lbf 000 3000 2000 1000 0 0 20 40 60 80 100 120 140 160 180 ?,  ° 6-13 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-31 A horizontal water jet impinges normally upon a vertical plate which is held on a frictionless track and is initially stationary. The initial acceleration of the plate, the time it takes to reach a certain velocity, and the velocity at a given time are to be determined.Assumptions 1 The flow is steady and incompressible. 2 The water always splatters in the plane of the retreating plate. 3 The water jet is exposed to the atmosphere, and thus the pressure of the water jet and the splattered water is the a tmospheric pressure which is disregarded since it acts on all surfaces. 4 The tract is nearly frictionless, and thus fiction during motion is negligible. 5 The motions of the water jet and the cart are horizontal. 6 The velocity of the jet relative to the plate remains constant, Vr = Vjet = V. 7 Jet flow is nearly uniform and thus the effect of the momentum-flux correction factor is egligible, ? ? 1. Properties We take the density of water to be 1000 kg/m3. Analysis (a) We take the vertical plate on the frictionless track as the control volume, and the direction of flow as the positive direction of x axis. The mass flow rate of water in the jet is & m = ? VA = (1000 kg/m 3 )(18 m/s)[? (0. 05 m) 2 / 4] = 35. 34 kg/s The momentum equation for steady one-dimensional flow in the x (flow) direction reduces in this case to r r r & & & & F= ? mV ? ? mV > FRx = ? mi Vi > FRx = ? mV ? ? out ? in where FRx is the reaction force required to hold the plate in place.When the plate is released, a n equal and opposite impulse force acts on the plate, which is determined to ? 1N & Fplate = ? FRx = mV = (35. 34 kg/s)(18 m/s)? ? 1 kg ? m/s 2 ? ? ? = 636 N ? ? Then the initial acceleration of the plate becomes a= Fplate m plate = 636 N ? 1 kg ? m/s 2 ? 1000 kg ? 1 N ? ? ? = 0. 636 m/s 2 ? ? 18 m/s 1000 kg Waterjet Frictionless track This acceleration will remain constant during motion since the force acting on the plate remains constant. (b) Noting that a = dV/dt = ? V/? t since the acceleration a is constant, the time it takes for the plate to reach a velocity of 9 m/s is ? t = ? V plate a = (9 ? ) m/s 0. 636 m/s 2 FRx = 14. 2 s (c) Noting that a = dV/dt and thus dV = adt and that the acceleration a is constant, the plate velocity in 20 s becomes V plate = V0, plate + a? t = 0 + (0. 636 m/s 2 )(20 s) = 12. 7 m/s Discussion The assumption that the relative velocity between the water jet and the plate remains constant is valid only for the initial moments of motion when the plate velocity is low unless the water jet is moving with the plate at the same velocity as the plate. 6-14 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation.If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-32 A 90 ° reducer elbow deflects water downwards into a smaller diameter pipe. The resultant force exerted on the reducer by water is to be determined. Assumptions 1 The flow is steady, frictionless, one-dimensional, incompressible, and irrotational (so that the Bernoulli equation is applicable). 2 The weight of the elbow and the water in it is disregarded since the gravitational effects are negligible. 3 The momentum-flux correction factor for each inlet and outlet is given to be ? 1. 04. Properties We take the density of water to be 1000 kg/m3. Analysis We take the elbow as the control volume, and designate the entrance by 1 and the outlet by 2. We also designate the horizontal coordinate by x (with the direction of flow as being the positive direction) and the vertical coordinate by z. The continuity equation for this one-inlet one-outlet steady flow system is & & & & m1 = m 2 = m = 353. 4 kg/s. Noting that m = ? AV , the mass flow rate of water and its outlet velocity are 2 & m = ? V1 A1 = ? V1 (? D1 / 4) = (1000 kg/m 3 )(5 m/s)[? (0. 3 m) 2 / 4] = 353. 4 kg/s & & 353. kg/s m m = = = 20 m/s 2 ? A2 D 2 / 4 (1000 kg/m 3 )[? (0. 15 m) 2 / 4] The Bernoulli equation for a streamline going through the center of the reducing elbow is expressed as V2 = P V12 P V2 1 + + z1 = 2 + 2 + z2 ? g 2 g ? g 2 g > ? V 2 ? V22 ? ? P2 = P + ? g ? 1 1 ? 2 g + z1 ? z2 ? ? ? Substituting, the gage pressure at the outlet becomes ? (5 m/s)2 ? (20 m/s)2 1 kPa ? 1 kN ? P2 = (300 kPa) + (1000 kg/m 3 )(9. 81 m/s 2 )? + 0. 5 = 117. 4 kPa 2 ? 1000 kg ? m/s 2 1 kN/m 2 ? 2(9. 81 m/s ) ? ? The momentum equation for steady one-dimensional flow is & & ? F = ? ?mV ? ? ? mV . We let the xout in r r and z- components of the anchoring force of the elbow be FRx and FRz, and assume them to be in the positive directions. Then the momentum equations along the x and z axes become & FRx + P1,gage A1 = 0 ? ? mV1 & FRz ? P2,gage A2 = ? m(? V 2 ) ? 0 Note that we should not forget the negative sign for forces and velocities in the negative x or z direction. Solving for FRx and FRz, and substituting the given values, ? 1 kN & FRx = ? ?mV1 ? P1, gage A1 = ? 1. 04(353. 4 kg/s)(5 m/s)? ? 1000 kg ? m/s 2 ? ? ? (0. 3 m) 2 ? ? (300 kN/m 2 ) = ? 23. 0 kN ? 4 ? ? ? (0. 15 m) 2 ? + (117. 4 kN/m 2 ) = ? 5. 28 kN ? ? FRz ? 1 kN & FRz = ? ? mV 2 + P2, gage A1 = ? 1. 04(353. 4 kg/s)(20 m/s)? ? 1000 kg ? m/s 2 ? and 2 2 FR = FRx + FRz = (? 23. 0) 2 + (? 5. 28) 2 = 23. 6 kN FRx 30 cm Water 5 m/s ? = tan -1 FRz ? 5. 28 = tan -1 = 12. 9 ° FRx ? 23. 0 Discussion The magnitude of the anchoring force is 23. 6 kN, and its line of action makes 12. 9 ° from +x direction. Negative values for FRx and FRy indicate that the assumed directions are wrong, and should be reversed. 15 cm 6-15 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation.If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-33 A wind turbine with a given span diameter and efficiency is subjected to steady winds. The power generated and the horizontal force on the supporting mast of the turbine are to be determined. vEES Assumptions 1 The wind flow is steady and incompressible. 2 The efficiency of the turbine-generator is independent of wind speed. 3 The frictional effects are negligible, and thus none of the incoming kinetic energy is converted to thermal energy. Wind flow is uniform and thus the momentum-flux correction factor is nearly unity, ? ? 1. Properties The density of air is given to be 1. 25 kg/m3. Analysis (a) The power potential of the wind is its kinetic energy, & which is V2/2 per unit mass, and mV 2 / 2 for a given mass flow rate: ? 1 m/s ? V1 = (25 km/h)? ? = 6. 94 m/s ? 3. 6 km/h ? & m = ? 1V1 A1 = ? 1V1 Wind V1 1 2 D V2 ?D 2 4 2 = (1. 25 kg/m 3 )(6. 94 m/s) ? (90 m) 2 4 2 = 55,200 kg/s V (6. 94 m/s) & & & W max = mke1 = m 1 = (55,200 kg/s) 2 2 ? 1 kN ? ? 1000 kg ? m/s 2 ? 1 kW ? 1 kN ? m/s ? = 1330 kW ? ? FR Then the actual power produced becomes & Wact = ? wind turbineW max = (0. 32)(1330 kW) = 426 kW (b) The frictional effects are assumed to be negligible, and thus the portion of incoming kinetic energy not converted to electric power leaves the wind turbine as outgoing kinetic energy. Therefore, V2 V2 & & & & mke 2 = mke1 (1 ? ? wind turbine ) > m 2 = m 1 (1 ? ? wind turbine ) 2 2 or V 2 = V1 1 ? ? wind turbine = (6. 94 m/s) 1 – 0. 32 = 5. 72 m/s We choose the control volume around the wind turbine such that the wind is norm al to the control surface at the inlet and the outlet, and the entire control surface is at the atmospheric pressure.The momentum r r r & & equation for steady one-dimensional flow is F= ? mV ? ? mV . Writing it along the x-direction ? ? out ? in (without forgetting the negative sign for forces and velocities in the negative x-direction) and assuming the flow velocity through the turbine to be equal to the wind velocity give ? 1 kN & & & FR = mV 2 ? mV1 = m(V 2 ? V1 ) = (55,200 kg/s)(5. 72 – 6. 94 m/s)? ? 1000 kg ? m/s 2 ? ? ? = ? 67. 3 kN ? ? The negative sign indicates that the reaction force acts in the negative x direction, as expected.Discussion This force acts on top of the tower where the wind turbine is installed, and the bending moment it generates at the bottom of the tower is obtained by multiplying this force by the tower height. 6-16 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for c ourse preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-34E A horizontal water jet strikes a curved plate, which deflects the water back to its original direction.The force required to hold the plate against the water stream is to be determined. Assumptions 1 The flow is steady and incompressible. 2 The water jet is exposed to the atmosphere, and thus the pressure of the water jet and the splattered water is the atmospheric pressure, which is disregarded since it acts on all surfaces. 3 Friction between the plate and the surface it is on is negligible (or the friction force can be included in the required force to hold the plate). 4 There is no splashing of water or the deformation of the jet, and the reversed jet leaves horizontally at the same velocity and flow rate. Jet flow is nearly uniform and thus the momentum-flux correction factor is nearly unity, ? ? 1. Properties We take the density of w ater to be 62. 4 lbm/ft3. Analysis We take the plate together with the curved water jet as the control volume, and designate the jet inlet by 1 and the outlet by 2. We also designate the horizontal coordinate by x (with the direction of incoming flow as being the positive direction). The continuity equation for this one-inlet one-outlet steady & & & flow system is m1 = m 2 = m where & m = ? VA = ? V [? D 2 / 4] = (62. 4 lbm/ft 3 )(140 ft/s)[? (3 / 12 ft) 2 / 4] = 428. lbm/s r r r & & The momentum equation for steady one-dimensional flow is F= ? mV ? ? mV . Letting the ? ? out ? in reaction force to hold the plate be FRx and assuming it to be in the positive direction, the momentum equation along the x axis becomes & & & FRx = m(? V 2 ) ? m(+V1 ) = ? 2mV Substituting, 1 lbf ? ? FRx = ? 2(428. 8 lbm/s)(140 ft/s)? ? = ? 3729 lbf 2 ? 32. 2 lbm ? ft/s ? Therefore, a force of 3729 lbm must be applied on the plate in the negative x direction to hold it in place. Discussion Note that a nega tive value for FRx indicates the assumed direction is wrong (as expected), and should be reversed.Also, there is no need for an analysis in the vertical direction since the fluid streams are horizontal. 2 140 ft/s Waterjet FRx 1 140 ft/s 3 in 6-17 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-35E A horizontal water jet strikes a bent plate, which deflects the water by 135 ° from its original direction. The force required to hold the plate against the water stream is to be determined.Assumptions 1 The flow is steady and incompressible. 2 The water jet is exposed to the atmosphere, and thus the pressure of the water jet and the splattered water is the atmospheric pressure, which is disregarded since it acts on all surfaces. 3 Frictional and gravitational effec ts are negligible. 4 There is no splattering of water or the deformation of the jet, and the reversed jet leaves horizontally at the same velocity and flow rate. 5 Jet flow is nearly uniform and thus the momentum-flux correction factor is nearly unity, ? ? 1. Properties We take the density of water to be 62. 4 lbm/ft3.Analysis We take the plate together with the curved water jet as the control volume, and designate the jet inlet by 1 and the outlet by 2. We also designate the horizontal coordinate by x (with the direction of incoming flow as being the positive direction), and the vertical coordinate by z. The continuity equation for & & & this one-inlet one-outlet steady flow system is m1 = m 2 = m where & m = ? VA = ? V [? D 2 / 4] = (62. 4 lbm/ft 3 )(140 ft/s)[? (3 / 12 ft) 2 / 4] = 428. 8 lbm/s r r r & & The momentum equation for steady one-dimensional flow is F= ? mV ? ? mV . We let the x- ? ? out ? in nd z- components of the anchoring force of the plate be FRx and FRz, and assu me them to be in the positive directions. Then the momentum equations along the x and y axes become & & & FRx = m(? V 2 ) cos 45 ° ? m(+V1 ) = ? mV (1 + cos 45 °) & (+V 2 ) sin 45 ° = mV sin 45 ° & FRz = m Substituting the given values, 1 lbf ? ? FRx = ? 2(428. 8 lbm/s)(140 ft/s)(1 + cos45 °)? 2 ? ? 32. 2 lbm ? ft/s ? = ? 6365 lbf 1 lbf ? ? FRz = (428. 8 lbm/s)(140 ft/s)sin45 °? = 1318 lbf 2 ? ? 32. 2 lbm ? ft/s ? 2 140 ft/s Waterjet 135 ° FRz FRx 3 in 1 and 2 2 FR = FRx + FRz = (? 6365) 2 + 1318 2 = 6500 lbf , ? = tan -1 FRy FRx = tan -1 1318 = ? 1. 7 ° = 168. 3 ° ? 6365 Discussion Note that the magnitude of the anchoring force is 6500 lbf, and its line of action makes 168. 3 ° from the positive x direction. Also, a negative value for FRx indicates the assumed direction is wrong, and should be reversed. 6-18 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-36 Firemen are holding a nozzle at the end of a hose while trying to extinguish a fire.The average water outlet velocity and the resistance force required of the firemen to hold the nozzle are to be determined. Assumptions 1 The flow is steady and incompressible. 2 The water jet is exposed to the atmosphere, and thus the pressure of the water jet is the atmospheric pressure, which is disregarded since it acts on all surfaces. 3 Gravitational effects and vertical forces are disregarded since the horizontal resistance force is to be determined. 5 Jet flow is nearly uniform and thus the momentum-flux correction factor can be taken to be unity, ? ? 1. Properties We take the density of water to be 1000 kg/m3.Analysis (a) We take the nozzle and the horizontal portion of the hose as the system such that water enters the control volume vertically and outlets horizontally (thi s way the pressure force and the momentum flux at the inlet are in the vertical direction, with no contribution to the force balance in the horizontal direction), and designate the entrance by 1 and the outlet by 2. We also designate the horizontal coordinate by x (with the direction of flow as being the positive direction). The average outlet velocity and the mass flow rate of water are determined from V= V& A = V& ? D / 4 2 = 5 m 3 /min ? (0. 06 m) 2 / 4 1768 m/min = 29. 5 m/s & m = ? V& = (1000 kg/m 3 )(5 m 3 /min) = 5000 kg/min = 83. 3 kg/s (b) The momentum equation for steady one-dimensional flow is & & ? F = ? ?mV ? ? ? mV . We let out in r r r horizontal force applied by the firemen to the nozzle to hold it be FRx, and assume it to be in the positive x direction. Then the momentum equation along the x direction gives ? ? 1N ? = 2457 N & & FRx = mVe ? 0 = mV = (83. 3 kg/s)(29. 5 m/s)? ? 1kg ? m/s 2 ? ? ? Therefore, the firemen must be able to resist a force of 2457 N to hold t he nozzle in place. Discussion The force of 2457 N is equivalent to the weight of about 250 kg.That is, holding the nozzle requires the strength of holding a weight of 250 kg, which cannot be done by a single person. This demonstrates why several firemen are used to hold a hose with a high flow rate. FRz FRx 5 m3/min 6-19 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-37 A horizontal jet of water with a given velocity strikes a flat plate that is moving in the same direction at a specified velocity.The force that the water stream exerts against the plate is to be determined. Assumptions 1 The flow is steady and incompressible. 2 The water splatters in all directions in the plane of the plate. 3 The water jet is exposed to the atmosphere, and thus the pressure o f the water jet and the splattered water is the atmospheric pressure, which is disregarded since it acts on all surfaces. 4 The vertical forces and momentum fluxes are not considered since they have no effect on the horizontal force exerted on the plate. 5 The velocity of the plate, and the velocity of the water jet relative to the plate, are constant. Jet flow is nearly uniform and thus the momentum-flux correction factor can be taken to be unity, ? ? 1. Properties We take the density of water to be 1000 kg/m3. Analysis We take the plate as the control volume, and the flow direction as the positive direction of x axis. The mass flow rate of water in the jet is & m = ? V jet A = ? V jet 10 m/s 30 m/s FRx 5 cm Waterjet ?D 4 2 = (1000 kg/m 3 )(30 m/s) ? (0. 05 m) 2 4 = 58. 9 kg/s The relative velocity between the plate and the jet is V r = V jet ? V plate = 30 ? 10 = 20 m/s Therefore, we can assume the plate to be stationary and the jet to move with a velocity of 20 m/s.The r r r & & F= ? mV ? ? mV . We let the horizontal momentum equation for steady one-dimensional flow is ? ? out ? in reaction force applied to the plate in the negative x direction to counteract the impulse of the water jet be FRx. Then the momentum equation along the x direction gives ? ? 1N ? & & ? FRx = 0 ? mVi > FRx = mV r = (58. 9 kg/s)(20 m/s)? ? 1kg ? m/s 2 ? = 1178 N ? ? Therefore, the water jet applies a force of 1178 N on the plate in the direction of motion, and an equal and opposite force must be applied on the plate if its velocity is to remain constant.Discussion Note that we used the relative velocity in the determination of the mass flow rate of water in the momentum analysis since water will enter the control volume at this rate. (In the limiting case of the plate and the water jet moving at the same velocity, the mass flow rate of water relative to the plate will be zero since no water will be able to strike the plate). 6-20 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Comp anies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission.Chapter 6 Momentum Analysis of Flow Systems 6-38 Problem 6-37 is reconsidered. The effect of the plate velocity on the force exerted on the plate as the plate velocity varies from 0 to 30 m/s in increments of 3 m/s is to be investigated. rho=1000 â€Å"kg/m3† D=0. 05 â€Å"m† V_jet=30 â€Å"m/s† Ac=pi*D^2/4 V_r=V_jet-V_plate m_dot=rho*Ac*V_jet F_R=m_dot*V_r â€Å"N† Vplate, m/s 0 3 6 9 12 15 18 21 24 27 30 Vr, m/s 30 27 24 21 18 15 12 9 6 3 0 FR, N 1767 1590 1414 1237 1060 883. 6 706. 9 530. 1 353. 4 176. 7 0 1800 1600 1400 1200 1000 FR, N 800 600 400 200 0 0 5 10 15 20 25 30 Vplate, m/s 6-21PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you ar e using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-39E A fan moves air at sea level at a specified rate. The force required to hold the fan and the minimum power input required for the fan are to be determined. v Assumptions 1 The flow of air is steady and incompressible. 2 Standard atmospheric conditions exist so that the pressure at sea level is 1 atm. Air leaves the fan at a uniform velocity at atmospheric pressure. 4 Air approaches the fan through a large area at atmospheric pressure with negligible velocity. 5 The frictional effects are negligible, and thus the entire mechanical power input is converted to kinetic energy of air (no conversion to thermal energy through frictional effects). 6 Wind flow is nearly uniform and thus the momentum-flux correction factor can be taken to be unity, ? ? 1. Properties The gas constant of air is R = 0. 3704 psi? ft3/lbm? R. The standard atmospheric pressure at sea level is 1 atm = 14. 7 psi.Analysis (a) We take the control volume to be a horizontal hyperbolic cylinder bounded by streamlines on the sides with air entering through the large cross-section (section 1) and the fan located at the narrow cross-section at the end (section 2), and let its centerline be the x axis. The density, mass flow rate, and discharge velocity of air are 14. 7 psi P ? = = = 0. 0749 lbm/ft 3 RT (0. 3704 psi ? ft 3 /lbm ? R)(530 R) & m = ? V& = (0. 0749 lbm/ft 3 )(2000 ft 3/min) = 149. 8 lbm/min = 2. 50 lbm/s V2 = V& A2 = V& 2 ? D 2 / 4 = 2000 ft 3 /min ? (2 ft) 2 / 4 = 636. 6 ft/min = 10. ft/s & & ? F = ? ?mV ? ? ? mV . Letting the out in The momentum equation for steady one-dimensional flow is r r r reaction force to hold the fan be FRx and assuming it to be in the positive x (i. e. , the flow) direction, the momentum equation along the x axis becomes 1 lbf ? ? & & FRx = m(V 2 ) ? 0 = mV = (2. 50 lbm/s)(10. 6 ft/s)? ? = 0. 82 lbf 2 ? 32. 2 lbm ? ft/s ? Therefore, a force of 0. 82 lbf must be applied (through frict ion at the base, for example) to prevent the fan from moving in the horizontal direction under the influence of this force. (b) Noting that P1 = P2 = Patm and V1 ? , the energy equation for the selected control volume reduces to ?P V2 ? ?P V2 ? & & & & & m? 1 + 1 + gz1 ? + W pump, u = m? 2 + 2 + gz 2 ? + W turbine + E mech,loss > ? ? ? ? 2 2 ? ? ? ? Substituting, V & & Wfan, u = m 2 2 2 V2 (10. 6 ft/s) 2 ? 1 lbf 1W ? & & Wfan,u = m 2 = (2. 50 lbm/s) ? ? = 5. 91 W 2 2 2 ? 32. 2 lbm ? ft/s 0. 73756 lbf ? ft/s ? Therefore, a useful mechanical power of 5. 91 W must be supplied to 2000 cfm air. This is the minimum required power input required for the fan. Discussion The actual power input to the fan will be larger than 5. 1 W because of the fan inefficiency in converting mechanical power to kinetic energy. Fan 1 2 24 in 6-22 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-40 A helicopter hovers at sea level while being loaded. The volumetric air flow rate and the required power input during unloaded hover, and the rpm and the required power input during loaded hover are to be determined. Assumptions 1 The flow of air is steady and incompressible. 2 Air leaves the blades at a uniform velocity at atmospheric pressure. 3 Air approaches the blades from the top through a large area at atmospheric pressure with negligible velocity. 4 The frictional effects are negligible, and thus the entire mechanical power input is converted to kinetic energy of air (no conversion to thermal energy through frictional effects). 5 The change in air pressure with elevation is negligible because of the low density of air. 6 There is no acceleration of the helicopter, and thus the lift generated is equal to the total weight. Air flow is nearly uniform and thus the momentum-flux correction factor can be taken to be unity, ? ? 1. Properties The density of air is given to be 1. 18 kg/m3. Analysis (a) We take the control volume to be a vertical hyperbolic cylinder bounded by streamlines on the sides with air entering through the large cross-section (section 1) at the top and the fan located at the narrow cross-section at the bottom (section 2), and let its centerline be the z axis with upwards being the positive direction. r r r & & F= ? mV ? ? mV . Noting The momentum equation for steady one-dimensional flow is ? out ? in that the only force acting on the control volume is the total weight W and it acts in the negative z direction, the momentum equation along the z axis gives W & & ? W = m(? V 2 ) ? 0 > W = mV 2 = ( ? AV 2 )V 2 = ? AV 22 > V2 = ? A 1 where A is the blade span area, 15 m A = ? D / 4 = ? (15 m) / 4 = 176. 7 m 2 2 2 Then the discharge velocity, volume flow rate, and the mass flow rate of air in the unloaded mode become V 2,unloaded = m unloaded g = ? A (10,000 kg)(9. 81 m/s 2 ) (1. 18 kg/m 3 )(176. 7 m 2 ) = 21. 7 m/s Sea level 2 V&unloaded = AV 2,unloaded = (176. 7 m 2 )(21. m/s) = 3834 m 3 /s & munloaded = ? V&unloaded = (1. 18 kg/m 3 )(3834 m 3/s) = 4524 kg/s Load 15,000 kg Noting that P1 = P2 = Patm, V1 ? 0, the elevation effects are negligible, and the frictional effects are disregarded, the energy equation for the selected control volume reduces to ? P V2 ? ?P V2 ? V2 & & & & & & & m? 1 + 1 + gz1 ? + W pump, u = m? 2 + 2 + gz 2 ? + W turbine + E mech,loss > Wfan, u = m 2 ? ? ? ? 2 2 2 ? ? ? ? Substituting, ? V2 ? 1 kW ? (21. 7 m/s) 2 ? 1 kN & ? ? & = (4524 kg/s) W unloaded fan,u = ? m 2 ? ? = 1065 kW 2 ? 1 kN ? m/s ? 1000 kg ? m/s ? ? 2 ? 2 ? ? ? ? nloaded (b) We now repeat the calculations for the loaded helicopter, whose mass is 10,000+15,000 = 25,000 kg: V 2,loaded = m loaded g = ? A (25,000 kg)(9. 81 m/s 2 ) (1. 18 kg/m 3 )(176. 7 m 2 ) = 34. 3 m/s & mloaded = ? V&loaded = ? AV2, loaded = (1. 18 kg/m 3 )(176. 7 m 2 )(34. 3 m/s) = 7152 kg/s ? V2 ? (34. 3 m/s)2 & & = (7152 kg/s) Wloaded fan,u = ? m 2 ? ? 2 ? 2 ? ?loaded ? 1 kW ? 1 kN ? ? ? 1000 kg ? m/s 2 1 kN ? m/s ? = 4207 kW ? ? 6-23 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation.If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems Noting that the average flow velocity is proportional to the overhead blade rotational velocity, the rpm of the loaded helicopter blades becomes & V 2 = kn > V 2,loaded V 2, unloaded = & n loaded & n unloaded > & n loaded = V 2,loaded V 2, unloaded & n unloaded = 34. 3 (400 rpm) = 632 rpm 21. 7 Discussion The actual power input to the helicopter blades will be considerably larger than the calculated power input because of the fan inefficiency in converting mechanical power to kinetic energy. -24 PROPRIETARY MATERIAL.  © 200 6 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission. Chapter 6 Momentum Analysis of Flow Systems 6-41 A helicopter hovers on top of a high mountain where the air density considerably lower than that at sea level. The blade rotational velocity to hover at the higher altitude and the percent increase in the required power input to hover at high altitude relative to that at sea level are to be determined. Assumptions 1 The flow of air is steady and incompressible. 2 The air leaves the blades at a uniform velocity at atmospheric pressure. 3 Air approaches the blades from the top through a large area at atmospheric pressure with negligible velocity. 4 The frictional effects are negligible, and thus the entire mechanical power input is converted to kinetic energy of air. 5 The change in air pressure with elevation while hovering at a given locatio n is negligible because of the low density of air. 6 There is no acceleration of the helicopter, and thus the lift generated is equal to the total weight. Air flow is nearly uniform and thus the momentum-flux correction factor can be taken to be unity, ? ? 1. Properties The density of air is given to be 1. 18 kg/m3 at sea level, and 0. 79 kg/m3 on top of the mountain. Analysis (a) We take the control volume to be a vertical hyperbolic cylinder bounded by streamlines on the sides with air entering through the large cross-section (section 1) at the top and the fan located at the narrow cross-section at the bottom (section 2), and let its centerline be the z axis with upwards being the positive direction. r r & & F= ? mV ? ? mV . Noting The momentum equation for steady one-dimensional flow is ? ? out ? in that the only force acting on the control volume is the total weight W and it acts in the negative z direction, the momentum equation along the z axis gives W & & ? W = m(? V 2 ) ? 0 > W = mV 2 = ( ? AV 2 )V 2 = ? AV 22 > V2 = ? A where A is the blade span area. Then for a given weight W, the ratio of discharge velocities becomes V 2,mountain V 2,sea = W / ? mountain A W / ? sea A = ? sea ? mountain = 1. 18 kg/m 3 0. 79 kg/m 3 = 1. 222Noting that the average flow velocity is proportional to the overhead blade rotational velocity, the rpm of the helicopter blades on top of the mountain becomes & n = kV 2 > & n mountain V 2, mountain = & n sea V 2,sea > & n mountain = V 2, mountain V 2,sea & nsea = 1. 222(400 rpm) = 489 rpm Noting that P1 = P2 = Patm, V1 ? 0, the elevation effect are negligible, and the frictional effects are disregarded, the energy equation for the selected control volume reduces to ? P V2 ? ?P V2 ? V2 & & & & & & & m? 1 + 1 + gz1 ? + W pump, u = m? 2 + 2 + gz 2 ? W turbine + E mech,loss > Wfan, u = m 2 ? ? ? ? 1 2 2 2 ? ? ? ? or V2 V2 V3 & & Wfan,u = m 2 = ? AV2 2 = ? A 2 = 2 2 2 1 2 ?A? ? ? W ? ? = ? ? ? A ? 3 1 2 ?A? ? ?W ? ? ? ? ? A ? 1 . 5 = W 1 . 5 2 ? A 15 m Then the ratio of the required power input on top of the mountain to that at sea level becomes & Wmountain fan,u 0. 5W 1. 5 / ? mountain A = & Wsea fan,u 0. 5W 1. 5 / ? sea A 2 ? mountain ?sea = 1. 18 kg/m3 = 1. 222 0. 79 kg/m3 Sea level Load 15,000 kg Therefore, the required power input will increase by 22. 2% on top of the mountain relative to the sea level.Discussion Note that both the rpm and the required power input to the helicopter are inversely proportional to the square root of air density. Therefore, more power is required at higher elevations for the helicopter to operate because air is less dense, and more air must be forced by the blades into the downdraft. 6-25 PROPRIETARY MATERIAL.  © 2006 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission.Chapter 6 Momentum Analysis of Flow Systems 6-42 The flow rate in a channel is controlled by a sluice gate by raising or lowering a vertical plate. A relation for the force acting on a sluice gate of width w for steady and uniform flow is to be developed. Assumptions 1 The flow is steady, incompressible, frictionless, and uniform (and thus the Bernoulli equation is applicable. ) 2 Wall shear forces at surfaces are negligible. 3 The channel is exposed to the atmosphere, and thus the pressure at free surfaces is the atmospheric pressure. 4 The flow is horizontal. Water flow is nearly uniform and thus the momentum-flux correction factor can be taken to be unity, ? ? 1. Analysis We take point 1 at the free surface of the upstream flow before the gate and point 2 at the free surface of the downstream flow after the gate. We also take the bottom surface of the channel as the reference level so that the elevations of points 1 and 2 are y1 and y2, respectively. The application of the Bernoulli equation between points 1 and 2 gives P1 V12 P V2 + + y1 = 2 + 2 + y 2 ? g 2 g ? g 2 g > V 22 ? V12 = 2 g( y1 ? y 2 ) (1)The flow is assumed to be incompressible and thus the density is constant. Then the conservation of mass relation for this single stream steady flow device can be expressed as V&1 = V&2 = V& > A1V1 = A2V 2 = V& > V1 = V& A1 = V& wy1 and V2 = V& A2 = V& wy 2 (2) Substituting into Eq. (1), ? V& ? ? wy ? 2 ? ? V& ? 2 g ( y1 ? y 2 ) & ? ? ? ? wy ? = 2 g ( y1 ? y 2 ) > V = w 1 / y 2 ? 1 / y 2 ? ? 1? 2 1 2 2 2 g ( y1 ? y 2 ) > V& = wy 2 2 2 1 ? y 2 / y1 (3) Substituting Eq. (3) into Eqs. (2) gives the following relations for velocities, V1 = y2 y1 2 g ( y1 ? y 2 ) 1? y2 / 2 y1 and V2 = 2 g ( y1 ? y 2 ) 2 2 1 ? y 2 / y1 (4) We choose the control volume as the water body surrounded by the vertical cross-sections of the upstream and downstream flows, free surfaces of water, the inner surface of the sluice gate, and the bottom surface of r r r & & F= ? mV ? ? mV . The the channel. The momentum equation for steady one-dimensional flow is ? ? out ? in force acting on the sluice gate FRx is horizontal