Google Prediction Markets

Part I: Quickly assess how Google’s Prediction Markets have attempted to date. What exactly degree have the business sectors been effective or fruitless? 250 When the five Googlers got together to begin with this task, their principle objective was to dispatch an inward forecast market and test if groups would make more exact expectations than individuals’. To decide whether this undertaking was a triumph or not we have to decide our parameters of accomplishment. In addition, we additionally feel that the achievement will be connected with the period of the task. From the case we can see that this undertaking is as yet experiencing its initial steps, in spite of the framework has been running for seven quarters. To quantify achievement, we have to assess; first, how precisely the market was during that period, and second, how that data was incorporated into the dynamic procedure at Google. The framework really worked quite well on anticipating occasions, for example, propelling dates, competition’s activities. There are some basic limitations for example no cash traded, absence of cooperation, absence of decent variety, and so on that should be unraveled as these are urgent as in a huge and differing investment is vital to guarantee that the market works appropriately. Notwithstanding of these auxiliary concerns, we consider that the principal objective was accomplished. This achievement can be obviously estimated in Figure C of the situation where we can see the examination of the result of the occasion and what the market anticipated, that it’s directionally fruitful. The group needs to make sense of how to expel these limitations, propel investment and by and large, coordinate its expectation showcase inside Google’s dynamic procedure. To the degree that the business sectors have been effective, what choice predispositions talked about in class do you figure this procedure will take out or limit (comparative with traditional anticipating forms)? What mental predispositions are probably not going to be wiped out or may perhaps be exacerbated? 381 Volume of wagers, assorted variety of members and motivators are they key factors that separate markets from the regular anticipating process. These variables decrease the impacts of some dynamic predispositions while enhancing others. Accessibility of data. The gathering, in general, will utilize more data while foreseeing the result of an occasion, limiting the effect of this inclination. Those straightforwardly associated with the task will approach a ton of explicit data about the venture and all the time they bomb in their expectations since they are one-sided. They belittle or disregard the effect of the data they need. Untouchables, in any case, will either get new data their estimate (no doubt) or regardless of whether they approach a similar data, they may decipher it in an unexpected way (will speak later about affirmation predisposition). Accordingly, the figure will represent all the data introduced in the market, beating the predisposition of the traditional procedure. Affirmation Bias: Most of the individuals wagering on an occasion won't be engaged with it. Untouchables won’t take a gander at the data looking for affirmation of their convictions, and regardless of whether they do it’s far-fetched that those convictions will be adjusted over all the individuals from the market, what will in the long run limit the effect of this inclination. For a similar explanation, carelessness inclination will be likewise wiped out as untouchables won't be arrogance, and once more, if there are, those won't be adjusted. (Reference: Dolores Haze's appraisal of the estimation of GPM). Similarly relentless of inaccurate convictions will be additionally disposed of. Various convictions and desires are balanced when outsiders’ sees are joined all the while. Notwithstanding, there are a few predispositions that won't be wiped out. Those are, Surrounding the result. Like in a traditional procedure, answers will be related and impacted by the manner by which the inquiry is surrounded. In any case, it’s still conceivable that this impact will be some way or another limited. In the event that the market is huge and various, individuals may decipher the casing in various manners, and consequently one-sided themselves in various ways. Underwriting impact. Of course, the chiefs will in general proceed with what they are really doing (if the market isn't assorted enough this inclination can't be remedied, in the event that everybody asked is in Goggle, at that point they may be affected by this kind of predisposition). Under what conditions are forecast advertises destined to perform generally well and moderately ineffectively? 417 Efficient working of forecast markets, inside the setting of a partnership like Google, would rely upon the accompanying three perspectives: a) Volume of members: By the idea of market-based dynamic, we would require enormous and differing set of members. Bigger support set will take out different inclinations talked about before. Liquidity (capacity to exchange) will permit members to align their wagers and choices dependent on new data. b) Diversity: Diversity of thought, point of view and intentions inside the support set is likewise significant for expectation markets. Google ought to energize investment from various topographies, various groups, changed degree of position and socioeconomics. This will make a market where members decipher data and signals in various manners with the goal that the aggregate activity standardizes for any predisposition. This assorted variety will dispose of any arrogance in dynamic and will give an important â€Å"outsider† see. The issue of assorted variety is very significant in shut markets (for example Google). This issue is enhanced when the choice close by identifies with the entire organization for example should Google get into equipment business or what will Google’s contender do? The market all in all may be pompous in these circumstances. A large portion of the individuals working at Google will in general have a comparable perspective, they all work and grasp Google’s culture so at some level they are comparative and think the same, this is an issue for an expectation advertise. c) Alignment of Incentives: Volume and assorted variety are unquestionably essential conditions for legitimate working of business sectors. In any case, it’s the aim of interest that would direct the achievement. All members should act objectively and make the best hazard balanced wagers. In corporate settings, issues like group elements, odds of advancement, individual connections and so forth can come in the method of levelheaded wagers. The motivators to take an interest ought not meddle with the real dynamic. Motivating forces can be lined up with financial increases, notoriety, achievements or other non-money related prizes. Also, this arrangement ought to be directed by how a corporate is wanting to utilize markets. Markets need to find some kind of harmony among privacy and straightforwardness. d) Transparency: Finally we imagine that is extremely significant that the market is straightforward and private. The entirety of the individuals need to have the assurance that their positions are not delighted except if they need to do as such. For instance if a market opens to decide whether a task is going to meet a specific dead line and I imagine that it won't make it, however the venture administrator is a companion of mine then I need my situation to stay secret. Part II: How might you use expectation markets to settle on better choices at Google? Ensure that you address the dangers and difficulties of supplanting increasingly customary determining forms with expectation markets. Additionally, talk about how you would alter how forecast markets have been utilized up until this point. In doing as such, you should concentrate on â€Å"organizational design† issues, (for example, interest and whether exchanges ought to be mysterious) not â€Å"market mechanism† issues, (for example, regardless of whether short selling is allowed). Note: This examination should expand on however not rehash what was written in Part I. Words: 807 In request to utilize expectation markets help better choice, Google (or any association) needs to make the accompanying strides: a. Verify that business sectors lead to better choices inside the setting of choices that their supervisors make b. Encourage the production of proficient expectation markets with right mot ivating forces c. Teach the chiefs about business sectors and incorporate markets with association Google ought to follow a staged methodology. Change Phase: During this stage, Google should set up the business sectors, empower investment and thoroughly test if expectation markets lead to better choices. There ought to be a control test of supervisors who are not offered access to forecast showcases in any capacity and a test who are urged to allude to expectation markets (despite the fact that an official choice would stay in the hands of the administrator). An official conclusions and the genuine outcome ought to be followed.

Ethical Principles and Codes of Practice Essay Example for Free

Moral Principles and Codes of Practice Essay Moral standards and codes of training can give direction in everyday practice. Dissect Peter’s circumstance for the situation study and arrive at a decision about what might be a proper reaction. This exposition will investigate the moral standards and code of training comparable to the contextual analysis of Peter, a man experiencing Alzheimer’s ailment and will propose a game-plan for Peter’s circumstance dependent on the utilization of these standards and the code. It will do this by looking at the term ‘ethics’ and will concentrate on four moral standards saw as comparative with the sorts of moral issues and difficulties met inside wellbeing and social consideration settings, these will be applied to the contextual investigation. Peter’s circumstance is that of a man, who, in line with his family, despondently (yet clearly essentially), moved to Parkside Manor, a little private consideration home. Recently Peter’s state of Alzheimer’s sickness has progressed and he has gotten continuously uninhibited. His conduct has made the staff question Peter’s position at the consideration home, as a portion of different occupants are starting to get grieved and bothered by his conduct. Some staff feel that with the quantity of occupants requiring consideration, Peter’s needs require additional time than they need to give. Anyway Peter’s family are undaunted in their choice for him to stay at Parkside. ‘Ethics’ are characterized as ‘the philosophical investigation of the virtue of human lead and of the standards and rules that should oversee it’ (Collins, 2006, p535). Singular qualities create after some time through socialization, childhood and encounters. These qualities when seen on an individual level, control singular activities. People working in the wellbeing and social consideration setting additionally hold proficient qualities got from proficient preparing and belief system. Choices are made utilizing both individual and expert qualities and all choices will have a moral measurement. Truly wellbeing and social consideration experts have been coordinated by standards and direction, empowering them to create what is po rtrayed as an expert ethical quality. Codes of training have for quite some time been viewed as guidelines directing practice, with away from of lead (General Social Care Council, 2010, p 4). These typically incorporate some exclusion’s, for example, revelation of data however they principally depict anticipated types of direct. In territories of wellbeing and social consideration moral standards are utilized alongside codes of training to guide and improve the dynamic procedure. These standards are identified with a feeling of making the best choice or that which is good and with thoughts of what is acceptable and awful practice (K217, Book 4, p28).This thought can be risky and can be seen both equitably and emotionally. Whenever saw from a target perspective, who ought to be trusted to realize what is the goal truth? In the event that emotional, who is the one whose assessment ought to be tuned in to? Questions, for example, these are frequently at the center of situations. Experts working inside wellbeing and social consideration conditions don't simply manage choices dependent on the privilege and great. Thought ought to likewise be given to ‘ethical dile mmas’, these are circumstances when two decisions are evident, both equivalent in profound quality and morals (K217, Book4, p29). Pattison and Heller (2001) propose, morals and worth issues clear a path through typical, day by day medicinal services practice, the translation of which is available to more than one clarification (K217, Offprints, p131). In spite of the fact that standards control activities, there is as yet a need to survey a circumstance and devise a fitting reaction. This appraisal and reaction get from an individual’s qualities and preparing as much as from standards. Moral standards are significant in the field of wellbeing and social consideration. Experts need to be able to make educated, moral and reasonable choices identifying with the people in their consideration. This can be troublesome when confronted with a difficult case. Utilizing a system to build up an organized perspective through a specific moral circumstance or challenge can be useful. The ETHICS system was created to help individuals working in care settings and offers an organized method of evaluating a strategy so as to go to a morally educated choice. It underlines the should have the option to choose a game-plan dependent on direction, data and built up standards, just as the individual’s convictions. The system expects specialists to right off the bat, Enquire about the applicable realities of the case, Think about the alternatives that are accessible to all included, Hear the perspectives on everybody (counting administration client, relatives and significant suppliers), Identify any important moral standards and qualities which may assist with controlling the decisionâ€making procedure, Clarify the importance and results of any key qualities lastly Select a strategy offering supporting contentions (K217, Book4, p32). When considering the contextual investigation, four moral standards will be analyzed. These are: regard for self-rule, non-impropriety, value and equity. The standards are viewed as the beginning stages for the improvement of moral ways to deal with care work on, giving a reasonable arrangement of standa rds, which instead of offering straightforward replies answers to moral issues, set out valuable core values for professionals when confronted with dubious choices (K217, Book 4, p34). In Peter’s circumstance, Autonomy or self-assurance is intricate. Regard for Autonomy alludes to a promise to regard the dynamic ability of a self-ruling person. Self-sufficiency is the opportunity to go about as an individual wishes, to have the option to settle on choices about their own life and not to be constrained by others. The contextual analysis brings up that Peter ‘unhappily’ left his home, in line with his family to move into Parkside Manor, showing that Peter had no power over this circumstance. This absence of option to pick where he lives, legitimately encroaches on Peter’s capacity to be independent and settle on contemplated educated decisions. Beauchamp and Childress (2009) distinguish two zones essential for self-rule: Liberty or autonomy from control and Agency, the limit with regards to ponder activity (K217, Book 4, p39). While applying this rule to Peter’s case, it could be contended that a conclusion of Alzheimer’s limits his capacities to settle on choices for himself, restricting limit with regards to deliberate activity thus lessening Peter’s capacity to work as a self-sufficient person. The codes of training for social consideration laborers (2010) state: ‘a social consideration specialist must regard the privileges of administration clients while trying to guarantee that their conduct doesn't hurt themselves or others’ (General Social Care Council, 2010, p9, 4.2). This causes an irreconcilable circumstance between Peter’s rights to act in a way that he picks and that of different inhabitants, who have the right to have the option to move openly about the home without the danger of being disturbed or bothered by Peter’s activities. Staff may wish to find a way to limit the potential danger of Peter’s conduct making mental mischief and upset different occupants and by following danger evaluation arrangements could survey the potential dangers in this circumstance (General Social Care Council, 2010, p9, 4.2). Recognizing unsafe conduct is multifaceted and not entirely clear. The appraisal of hazard could have genuine ramifications for Peter maybe prompting a constraining of his privileges and freedom in light of a legitimate concern for shielding others from hurt (K217, Book 4, p60). Hence over security or superfluous confinement could be viewed as an encroachment upon Peter’s human rights (K217, Book 4 p65). The contextual investigation doesn't precisely bring up if Peter has the psychological ability to comprehend that his activities could be troublesome and upsetting for other people. This being the situation it might likewise be proper to converse with both Peter and his family about the circumstance so as to discover an answer. As the code of training keeps up, ‘care laborers must advance the autonomy of administration clients and help them to comprehend and practice their rights’ (General Social Care Council, 2010, p8, 3.1). It is recommended, that in situations where dynamic limit is regarded to be impeded, regard for independe nce may include the consideration specialist acting suitably in an individual’s ‘best interests’ (K217, Book 4, p40). The trouble here is that Peters eventual benefits can't be seen without considering the eventual benefits of different occupants, care laborers and family members. This shows the constraints of the code of training in taking a restricted moral view as opposed to attempting to take a more extensive and progressively adjusted point of view. Helpfulness and the advancement of government assistance are worried about the arrangement of advantages and the parity of these against chance in the consideration and treatment of administration clients. It necessitates that care suppliers make a positive commitment to help other people, not simply shun demonstrations of mischief. It could be contended that in Peter’s case, moving into a private setting might be viewed as ‘doing good’. The hypothesis of value or ‘doing good’ is inserted in wellbeing and social consideration practice. Albeit, as opposed to being clear in its endeavors to understand moral predicaments, usefulness can be seen as being somewhat dubious (K217, Book4, p34). The utilization of value in Peter’s circumstance could be viewed as a dubious one. Th e need to ‘do good’ in this circumstance could be believed to be against Peter’s eventual benefits, as on account of assent. The contextual analysis implies the way that Peter’s family are settling on choices on b

Kids Describe a World Without Libraries

Kids Describe a World Without Libraries While we at the Riot take some time off to rest and catch up on our  reading, were re-running some of our  favorite posts from the last several months. Enjoy our highlight reel, and well be back with new stuff on Monday, January 6th. This post originally ran August 15, 2013. _________________________ Sometimes the job has its perks. A few years ago, I was asked to be a judge for a student library essay contest being held by a local councilman. The topic of the contest was The Future of Libraries, and the kids who entered produced thoughtful, enlightening, (and quite amusing, in some cases) results. I will admit that one of the darker entries, which sadly did not win, might have been my favorite. (See partial text below; click here for the full essay. Its worth it.) This kid doesnt mess around. So when I was asked to be a judge for the contest again this year AND also to host the awards ceremony at my library, I jumped at the chance. The essay contest is not only a great opportunity for students to show off their writing chops, but it also gives me a candid look at what they really think about the function of libraries in their young lives. Plus, these kids will (with any luck) grow up to be lifelong library users, so we need to pay attention to their thoughts and ideas. Theyre pretty smart. This years essay topic was A World Without Libraries a topic that has increasing relevance as THE MAN seem to want to squash libraries at every turn. Students from local elementary schools, middle schools, and high schools were asked to share their views about what the world might be like without libraries and how that would potentially affect their lives. (Note: this must have been part of a broader lesson unit, as the topic also came up during a class visit I had at my library a few months ago, sparking a rather poignant and hilarious discussion.) I was in charge of choosing three finalists from about 50 or so elementary school entrants, and I can honestly say that each essay I read had value. Of course, there are always standout ideas, so I chose my personal 10 favorite lines from 10 different essays. I hope you enjoy reading the kids thoughts as much as I did. (Any spelling, syntax, or punctuation errors by the students have been kept intact.) Top 10 A World Without Libraries Essay Quotes From Brooklyn Kids: 1) A library is a need in our community. That is what Im trying to explain to you. A library has knowledge and we can never get too much knowledge. Lets not forget to mention that going to the library is FUN! 2) So a world without libraries would be a dump. People wont find as much information. Peoples education will decline. A world without libraries? Well the world will be upside down! 3) Libraries still teach and educate people. They hold reading classes, English as a Second Language groups, they organize various book related activities for children, invite famous authors to give speeches, lend us audio and videotapes, help us look for a job, and finally, conduct a research. Can you imagine something like this happening in the world without libraries? Excuse me, said one gentleman, Is there any chance you have change for a dollar? What? I have no nothing, a stranger screamed back. What have we become? Do we know how to use proper grammar and correct English? Why dont we ask the librarians, listen to them speak beautiful English while they are answering our questions. Have you ever met a librarian whose language skills you did not like or who was not able to tell you all about the subjects ranging from classics to modern literature? What would happen to these well-educated, well-read people if we closed our libraries? It would be like losing a hand. 4) I love reading and without libraries I would be super bored. Libraries connect us to books. Life would be horrible without libraries. 5) Close your eyes. Imagine you are walking through New York City. You see many empty lots say Lot for rent or Century 21 is going to be here. You were going to the library to get a book on plate tectonics when it hits youNO LIBRARIES! We would have no places where you could just get in the zone and read. When you are going to a library, you are always welcome. You are away from all the city hustle and bustle madness. You are CALM. They always said Silence is golden.' 6) At the library you can find anything from aardvark to zebu. When you are there and reading you are holding a work of art in your hands. You can feel the authors presence telling you the story. Wouldnt Benjamin Franklin be upset if there were no libraries and he worked so hard on inventing them? 7) Libraries make people feel at home. When I first moved to New York City, coming from a more rural area of New York, everything was very confusing and weird but the library was something I had seen before. 8) They say everyone smiles in the same language. If this is true then everyone is speaking in the same language when they visit a library. 9) Libraries make the world go round. They keep the little sanity we have left here. And finally, 10) The world without libraries is like a cone without ice cream. And these were only some of the great things the kids wrote about libraries. When all the finalists came to my branch to get their awards from the City Council and read their essays out loud in front of their proud parents, I was blown away (and often moved to tears what can I say, Im a big sap) by how much the library has meant to them so far in their lives. So there you have it, folks. Listen to the children! _________________________ Sign up for our newsletter to have the best of Book Riot delivered straight to your inbox every two weeks. No spam. We promise. To keep up with Book Riot on a daily basis, follow us on Twitter, like us on Facebook, , and subscribe to the Book Riot podcast in iTunes or via RSS. So much bookish goodnessall day, every day. Sign up to The Kids Are All Right to receive news and recommendations from the world of kid lit and middle grade books. Thank you for signing up! Keep an eye on your inbox.

Biology Lab on Osmosis - 1881 Words

Michelle Kim 2012.1.20 Biology Iso-osmolar Concentration of Carrot Cells Lab INTRODUCTION For a more thorough understanding of this lab introduction, the concepts of, iso osmolar, membrane, equilibrium, and concentration gradient evaluated. Iso osmolar can be known as the point in which the substance of experimentation faces no change despite the amount of solute inside the solvent( because the solvent and solute concentration is equal. This is where the line on a graph would cross on the x-axis). Selectively permeable membrane can be defined as a microscopic double layer of lipids and proteins that bounds cells and organelles and forms structures within cells and it controls what comes in and out of the cell. Equilibrium is the†¦show more content†¦The result showed the affects of osmosis, where particles moved to achieve equilibrium. The 0.2 M sucrose had a +8.37% change in mass as a class average and our group and +9.52%. The initial mass for these carrots were 2.1g and became 2.3g when the 2 days had ended. This happened because of the same reason for the 0.0 M sucrose, where the concentration of particles were greater inside the cell compared to the outside of the cell, causing the water molecules moving into the cell through the semi permeable membrane. However, the solution the carrots were dunked into had a 0.2 M sucrose, unlike the first solution. This caused the mass of the carrot to change less because there was already some particles outside of the cell, allowing for equilibrium to become reached a lot faster than 0.0 M sucrose. In 0.4 M sucrose, there was a class average of -2.34% and we had -4.76%. The initial mass was 2.1g with a final mass of 2.0g. This was the first solution to have a negative percentage change in mass from the other six. There was a decrease in mass of the carrot because water had moved from the carrot sticks into the solution around is trying to achieve equilibrium. The water molecules had moved from high concentration into lower concentration, moving our of the carrot cells, causing them toShow MoreRelat edBiology Osmosis Lab Report Essay1890 Words   |  8 PagesOsmosis Lab Report by Evan Gerber Claire Cambron First Lab Report Wednesday 10:30am February 20, 2013 Theresa Gburek Abstract The major objective of the experiment was to test the effect of the concentration gradient on the diffusion rate. It was hypothesized that the greater the stronger the concentration gradient, the faster the rate of diffusion would be. To test this, dialysis tubes were submerged in different concentration fructose solutions. We weighed the tubes at specificRead MoreAp Biology Egg Osmosis Lab Essay658 Words   |  3 PagesAP Biology August 23, 2012 Egg Osmosis Lab Definition of osmosis: The diffusion of water across a selectively permeable membrane from high to low concentrations Hypothesis: If I place an egg in vinegar, then the outer layer of the egg is going to become slimy and look like rubber. It will also become larger and bubbles will form on and around the egg. Hypothesis: If I place an egg in corn syrup, then the egg will become small and the outer layer will not look like rubber any longer. Day one: Read MoreBiology Lab Report Ib Hl Osmosis1928 Words   |  8 PagesBiology Lab Report 2 Investigating the phenomenon of Osmosis in plant tissues: Potato in different concentrations of NaCl Tutor: Maria Tsaousidou By Marina Gkritzioudi Biology Lab Report 2 Investigating the phenomenon of Osmosis in plant tissues: Potato in different concentrations of NaCl Tutor: Maria Tsaousidou By Marina Gkritzioudi Investigating the phenomenon of Osmosis in plant tissues: Potato in different concentrations of NaCl Introduction: Osmosis is the movement ofRead MoreOsmosis Potato Lab Report Biology 4u Essay2115 Words   |  9 PagesIntroduction The movement of water molecules across a semi-permeable membrane is the process of osmosis. If there is a solute and a solvent, each containing different concentration levels, then the water would move along its concentration gradient until each side of the membrane are equal. The water moves because the membrane is impermeable to the solute and the solute concentrations may differ on either side of the membrane. Water molecules may move in and out of the cell, but there is no net diffusionRead MoreConclusion And Evaluation Of Osmosis Potato Lab889 Words   |  4 PagesSaam Baharmand Period 5 11 October 2014 Conclusion and Evaluation of Osmosis Potato Lab Hypothesis: I believe that the O Molar (M) solution of sugar and distilled water will be isotonic because there is no sugar in the solution. This Hypothesis was not supported by the results of the lab. 1) The line graph of the data collected shows the least amount of change in mass (1.8%) in the potato soaked in the 0.2M sugar solution. 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The purpose of this experiment was to study the process of osmosis. In order to test osmosis, eggs that had been soaking in vinegar were taken and placed in four beakers of solution with different levels of glucoseRead MoreCell Membrane Lab Essay927 Words   |  4 PagesLab #1: Cell Membrane Prepared for Gary V. Lawrence Biology 0983 By Zane Jeffels Partners: Lily Juno, Huynh, and Lin Yan Sun Preformed: October 11th, 2010 Due: October 25th, 2010 King Edward Campus- Rm. 3275 Vancouver Community College Abstract The purpose of this lab was to determine if hemolysis would occur, and how long it would take to occur to red blood cells when blood suspension is introduced to solutions prepared at different temperaturesRead MoreG7Ikhgfcutifyguhj1668 Words   |  7 PagesClara Skepple Miranda Wilby, Sarah Cavanagh Thursday, March 3 2016 Observing Diffusion and Osmosis INTRODUCTION: Related Theory: The cell membrane is the outermost boundary of the cell, made up of proteins and lipids. This membrane holds the cell together and establishes the movement of materials that go into and out of the cell. This is a selectively permeable membrane: a barrier that allows some molecules to pass through, but prevents other molecules from penetrating (1). Passive transport isRead MoreThe Concentration Of Solutes Affects The Rate Of Osmosis959 Words   |  4 Pagesof Osmosis Chintan Jani Biology 101-01 Dr. Reynolds October 6, 2016 Abstract The purpose of this lab was to observe the osmosis rates and mass changes of dialysis tubes. To this three-dialysis tubes with differing sucrose levels were tested on their rate of osmosis and weighed at 15-minute intervals. The results found described that as the sucrose level increases the rate of osmosis increased as well. Introduction The purpose of this experiment was to determine if the rate of osmosis has

The Rise of Enlightened Sexism - 622 Words

The rise of enlightened sexism: How pop culture took us from girl power to girls gone wild Douglas’ humorous and well informed way of writing really inspired me. From examples of magazines, media, television shows, films, retail, and even in music she described and compared to us what is going on among these examples and how real women today are really living their lives. Douglas presents an analysis of how women are presented to the public and how we continue to be treated as inferior to men despite the strides of feminism. After reading this book, I even find myself reading or watching something and pretty much look to see if it is women friendly or not. This is something I really never done before until now. This book definitely got me to think about feminism and the role it plays in my life. This book’s major argument is how women are shown by contemporary media and popular culture in mixed messages. Douglas focuses on the ways women are portrayed in popular music, such as dancers wearing barely any clothes and doing inappropriate things in rap videos; to the empowered women warriors in television, such as Xena: Warrior Princess, Dark Angel and Buffy the Vampire Slayer; to the female players, such as Sarah Palin and Hilary Clinton. Her arguments and points are very valid, I personally think. â€Å"Since the 1990s the mass media has increasingly reported that women have â€Å"made it,† that they achieved gender equality. On television women occupy important jobs like doctors,Show MoreRelatedAnalysis Of Disney s And Fat Phobic Appearance Personality Correlation2223 Words   |  9 Pagesare merely scrawl, yet deemed as Arabic by the movie’s creators. Jasmine is far underdressed for her culture, and would have worn longer, looser clothing to show status as a monarch. 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Term Paper on Poverty Free Essays

Term Paper on Poverty Prejudice, affluence, and poverty in America are linked issues. Works by four authors discussed in this essay, Takaki, Fallows, Olds, and Gioia, help us to understand how the social issues of class and race are intertwined, making an analysis of both necessary for an adequate understanding of any one individually. While the authors discussed here approach the issues from different angles, their works taken side by side clearly show us how prejudice helps the affluent shrug off responsibility toward the poor, offering ‘explanations’ as to why some groups (or persons) remain in poverty and others do not. We will write a custom essay sample on Term Paper on Poverty or any similar topic only for you Order Now Additionally, it is argued that those living in affluence – and thus those with the means to significantly address the poverty issue – may, in fact, have a reduced awareness of the existence and reality of poverty. As a result, not only is poverty per se not addressed (we don’t address what we don’t see), but the existing myths and prejudices that help to maintain class divisions, both in society at large and embedded in our legal and social structures, remain unchallenged. However, it is only by examining both the objective nature of the current era together with prejudice and the self-justification of the affluent that one can understand how prejudice, affluence, and poverty are intertwined. The nature of money, according to Gioia’s poem titled simply â€Å"Money†, shapes the reality of life for both the rich and the poor, according to how much they have or don’t have. Gioia’s poem reminds us of the many meanings we accord to money, how we need it and spend it, and how it functions in our economy. One of the clear messages in Gioia’s poem is that money, itself, does not discriminate. It is what it is regardless of who has it, but for those who have it, it grows and multiplies. For those who don’t have it, or don’t have enough of it, it does not. If money itself does not discriminate, how do we account for the gap between those who are affluent and those who are poor? What prevents some from getting it, while others have enough for it to grow? How we answer this question, and the logic behind our answer, is very connected to policy decisions we make concerning poverty, and how effective we are in addressing it. One of our traditional explanations for the why the poor are poor and the rich are rich, according to the American ideology, is that the poor are those who have not worked sufficiently to gain money. Likewise, those who have money, according to the same ideology, are those who have been frugal, worked hard, saved, wisely invested, and who have otherwise ‘lived right’. Takaki, in his article â€Å"Race at the End of History†, provides a summary of how this is embedded in our ideology: â€Å" The American dream still holds promise to all us as Americans. Everyone, regardless of race, can make it into the mainstream through hard work and private effort. † (p. 387). This kind of definition, and the ideology behind it, makes it possible to approach policy issues in such a way that places overwhelming responsibility on those who are poor for their own plight. As Takaki points out, our emphasis is on the fact that success is to be achieved through ‘private’ means, rather than government assistance (p. 387). Addressing poverty then becomes a question of getting those who are not working hard enough, not ‘living right’, to do so. This definition of poverty allows us to say, those who have a lion’s share of wealth deserve that wealth, and those who are in poverty, deserve that poverty. Viewed this way, there is no reason, then, to seriously listen to claims of ‘glass ceilings’ or discrimination, or to look in any other way at prejudices built into our social and legal structures that unfairly increase the odds for some, and reduce them for others. How is it that, in the face of evident continued poverty among certain ethnic or racial groups, we continue to believe in this ideology? Surely, by now enough evidence of systematic discrimination, glass ceilings, and other obstacles for specific racial and ethnic (and gender) groups has shown us that the American dream as summed up by Takaki is based at least partially on a myth. Yet many people still agree with, for example, what Takaki suggests (p. 385) Francis Fukuyama’s explanation is: that poverty is a matter of cultural difference. Parillo, in â€Å"Causes of Prejudice†, and Fallows in â€Å"The Invisible Poor† each help us to understand forces at work that help to perpetuate the myth even in the face of a contradictory reality. Parillo points to prejudice and the continuation of prejudice through the socialization process. Defining prejudice as â€Å"an attitudinal ‘system of negative beliefs, feelings, and action-orientations regarding a certain group or groups of people’† (p. 548), Parillo argues that, through the socialization process, prejudicial views consciously or unconsciously adopted during childhood can then continue into adulthood, and translate into prejudicial choices and behavior in work, social life, and life choices. Additionally, widespread and generally shared prejudicial beliefs and attitudes toward specific groups can be implicitly (or explicitly) reinforced by society at large through, for example, the legal system and cultural norms (p. 557). New generations may not be alert to these subtle reinforcers of prejudicial attitudes and practices, and therefore may not question them. The prevailing stereotypes and prejudices are thus maintained and continued as they are adopted by new generations, and as they continue to be sanctified by the surrounding legal and societal framework. If children acquire their beliefs from their parents through socialization, what prevents them from questioning those values? Surely, we are not all sheep, that unthinkingly accept everything we hear. One explanation that Parillo offers (pp. 550-551) is ‘Self-Justification’, that we need â€Å"reassurance that the things we do and the lives we live are proper, that good reasons for our actions exist. † One way in which this surfaces, he argues, is through a dominant group convincing itself that it is superior to other groups, causing them to associate less frequently or not at all with those groups it deems inferior. Fallows article â€Å"The Invisible Poor† clearly shows how this phenomenon is a reality of our current era of ‘tech wealth’, describing the invisible social barrier between rich and poor people – a barrier so great as to make the poor ‘invisible’ to the rich. Within the tech wealth era, according to Fallows, the production of wealth involves fewer ‘blue collar workers’, so that those directly benefiting from it are not confronted with the realities, struggles, and needs of those less like them. In terms of economic background, there is more similarity between the ‘workers’ producing and benefiting from the new wealth. Second, the nature of work within the tech industry isolates those within it into an insulated world. Long working hours, a minimal amount of leisure time, and social lives primarily focused around those within the same world further contributes to the lack of awareness and connectedness to the rest of the world around them. Third, he points to the ‘racial meritocracy’ of the tech industry, with workers and contributors coming from all corners of the globe. He argues that this racial mix among the tech wealthy leaves them out of touch with the more basic and traditional racial tensions among the less wealthy, and the ways in which those in minority groups not associated with the tech wealthy are still disadvantaged. While Fallows offers a great deal of support for these specific phenomena of the tech wealth era as objective phenomena, which may indeed be at work, combining an analysis of these phenomena with Parrillo’s analysis of prejudice and self-justification offers a fuller understanding of our current era. Sharon Olds, in her poem â€Å"From Seven Floors Up† shows, for example, how even if there are objective forces at work such as those discussed by Fallows, there is still an attitudinal factor at work: when those more affluent are confronted with the reality of poverty, they are looking from seven floors up, through prejudice and self-justification, will more likely (however unwittingly)do not believe it could be a reality of their lives. In sum, given that money itself does not discriminate, and given the overwhelming evidence that there are obstacles to wealth other than the personal failure to achieve the ‘American Dream’, we must look for a fuller explanation of the gap between the rich and the poor. The relationship between affluence and poverty consists not only of objective forces such as new forms of wealth production or characteristics of new economic eras, but more concretely of prejudice. The very real obstacles to wealth encountered by specific societal groups, and embedded in our social and legal structures ,are not only due to the transference of values from one generation to the next, but due to the continued need for self-justification among the affluent. The product of self-justification, prejudice, is the link between affluence and poverty that needs to be analyzed and addressed if social policies concerning poverty are to be effective. How to cite Term Paper on Poverty, Essays

Tutorial of Kinemtatics Essay Example

Tutorial of Kinemtatics Essay Applied Science Department (ASD) Centre for Foundation Studies and Extension Education (FOSEE) PPH 0095 Mechanics Foundation in Engineering ONLINE NOTES Chapter 2 Kinematics FOSEE , MULTIMEDIA UNIVERSITY (436821-T) MELAKA CAMPUS, JALAN AYER KEROH LAMA, 75450 MELAKA, MALAYSIA. Tel 606 252 3594 Fax 606 231 8799 URL: http://fosee. mmu. edu. my/~asd/ PPH0095 MECHANICS Contents 2. 0 2. 1 2. 2 2. 3 2. 4 2. 5 2. 6 2. 7 2. 8 2. 9 2. 10 2. 11 2. 12 2. 3 Introduction Definitions of Linear Motion Distance Displacement Speed and Velocity Average Velocity Instantaneous Velocity Average Acceleration Instantaneous Acceleration Equations of Linear Motions Motion Graphs Free Falling Objects under gravity Projectile Motion Uniform Circular Motion ASD 2011/12 KINEMATICS 1/23 PPH0095 MECHANICS Mind Map ASD 2011/12 KINEMATICS 2/23 PPH0095 MECHANICS OBJECTIVES Upon completion of this chapter, you should be able to: 1) 2) 3) 4) 5) define distance, displacement, velocity, acceleration. know how to apply all the equation for linear motion with constant acceleration. raw graph velocity versus time , distance versus time and explain them. understand the concept of free fall and should be able to solve the problem. understand the concept of projectile motion and uniform circular motion and should be able to solve the problem. 2. 0 INTRODUCTION Kinematics is the branch of mechanics which studies the motion of objects without considering the forces that cause the motion. Vector quantities such as displacement, velocity, and acceleration are involved. The study of the motion of objects under the action of forces is called dynamics. The study of the motion of objects, and the related concepts of force and energy, form the field called mechanics. Mechanics is customarily divided into two parts i. e. kinematics and dynamics. †¢ Kinematics : the description of how objects move. Kinematics in one dimension : describing an object that moves along a straight line path, which is one dimensional motion. Kinematics in two dimensions : the description of the motion of objects that move in paths in two (or three) dimensions. †¢ Dynamics : deals with force and why objects move as they do. In this part we will solve the following questions : What akes an object at rest begin to move ? What causes a body to accelerate or decelerate ? What is involved when an object moves in a circle ? We can answer in each case that a FORCE is required. 2. 1 †¢ †¢ DEFINITIONS of LINEAR MOTION Linear motion is motion along a straight line. Three types of motion: †¢ Translational †¢ Rotational †¢ Vibrational A SD 2011/12 KINEMATICS 3/23 PPH0095 MECHANICS †¢ Figure 1 †¢ †¢ We only discuss objects that move without rotating (Figure 1a) Motion in straight line; †¢ Vertical †¢ Horizontal †¢ Slanting Reference Frames †¢ †¢ Any measurement of position, distance or speed must be made with respect to a frame of reference. We will write a custom essay sample on Tutorial of Kinemtatics specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Tutorial of Kinemtatics specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Tutorial of Kinemtatics specifically for you FOR ONLY $16.38 $13.9/page Hire Writer It is always important to specify the frame of reference when stating a speed. In everyday life, we usually mean with respect to the Earth. Position †¢ For one-dimensional motion, we often choose the x axis as the line along which the motion takes place. †¢ The position of an object at any moment is given by its x coordinate. †¢ If the motion is vertical, as for a dropped object, we usually use the y axis. 2. 2 †¢ †¢ †¢ DISTANCE The length of the actual path or total path length. It depends on the frame of reference, for example, Ipoh is 200 km away from Kuala Lumpur. A set of coordinate axes represents a frame of reference. ASD 2011/12 KINEMATICS 4/23 PPH0095 MECHANICS 2. 3 †¢ †¢ DISPLACEMENT The change in position of the object, i. e. displacement is how far the objects is from its starting point. For example : A change from an initial position xi to the final position xf, the displacement is, ? x = xf xi. The symbol ? (delta) means change in. So ? x means the change in x which is the displacement. It is a quantity that has both magnitude and direction and represented in diagrams by arrows. Example 1 : A person walking 70 m to the east and then turning around and walking back (west) a distance of 30 m. †¢ Total distance = 100 m Displacement = xf xi = 40 m 0 m = 40 m Figure 2 2. 4 †¢ †¢ †¢ †¢ SPEED and VELOCITY The most obvious aspect of the motion of a moving object is how fast it is moving, i. e. its speed or velocity. Speed is simply a positive number, (i. e. a scalar: having magnitude only) with units. Velocity, on the other hand, is used to signify both the magnitude (numerical value) of how fast an object is moving and also the direction in which it is moving. (velocity is therefore a vector). Average Speed is defined as the total distance travelled along its path divided by the time it takes to travel this distance, i. . average speed = distance travelled time elapsed ASD 2011/12 KINEMATICS 5/23 PPH0095 MECHANICS 2. 5 †¢ AVERAGE VELOCITY Average velocity is defined as the displacement divided by the elapsed time, i. e. average velocity, v ave = †¢ †¢ x f xi displacement ? x = = time elapsed ? t t f ti Average velocity would be zero if start ing and ending point are the same. Unit : ms-1 Figure 3: Velocity of a car as a function of time at constant velocity. Figure 4: Velocity of a car as a function of time with varying velocity. 2. 6 †¢ †¢ †¢ INSTANTANEOUS VELOCITY The instantaneous velocity is the velocity at any instant of time. In general the instantaneous velocity at any moment is defined as the average velocity over an infinitesimally short time interval. We define instantaneous velocity as the average velocity in the limit of ? t becoming extremely small, approaching zero. v = lim †¢ ?t > 0 ?x dx = ? t dt Let ? t approach zero, ? x approaches zero as well. But the ratio ? x/? t approaches some definite value, which is the instantaneous velocity at a given instant. KINEMATICS 6/23 ASD 2011/12 PPH0095 MECHANICS 2. 7 †¢ AVERAGE ACCELERATION Acceleration specifies how rapidly the velocity of an object is changing. Average acceleration is defined as the change in velocity divided by the time taken to make this change, i. e. v f vi change of velocity ? v average acceleration, aave = = = time elapsed ? t t f ti Unit : ms-2 †¢ 2. 8 †¢ INSTANTANEOUS ACCELERATION The instantaneous , a , is defined as the limiting value of the average acceleration as we let ? t approach zero. instantaneous acceleration, a = lim ? dx ? d? ? 2 dv ? dt ? = d x a = = dt dt dt 2 ?t > 0 ? v dv = ? t dt since v = †¢ dx , so dt Acceleration tells us how fast the velocity changes, whereas velocity tells us how fast the position changes. x v= dt and dv d 2 x a = = dt dt 2 2. 9 †¢ EQUATIONS of LINEAR MOTIONS Many practical situations occur in which the acceleration is constant, i. e. the acceleration doesnt change over time. We now treat this situation when the magnitude of the acceleration, a, is constant and the motion is in a straight line. In this case, the instantaneous and average acceleration are eq ual. To simplify our notation, let us take the initial time in any discussion to be zero the elapsed time, t initial velocity , vo the position at time t is s the velocity at time t is v †¢ ASD 2011/12 KINEMATICS 7/23 PPH0095 MECHANICS †¢ †¢ †¢ The acceleration, which is assumed constant in time , will be a = Multiply both sides by t and get: ? v = vo + at at = v ? vo v ? vo t †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. ( 1. 9. 1 ) [omit s] velocity vo v O time t †¢ ?v +v? s=? o ? t ? 2 ? †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦( 1. 9. 2 ) [omit a] †¢ Substitute equation (1. 9. 1) into (1. 9. 2), s =( v o + v o + at )t 2 or s = vot + ? at2 †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. ( 1. 9. 3 ) [ omit v ] †¢ †¢ We now derive the fourth equation, which is useful in situations where the time, t is not known. From equation ( 1. 9. 1 ) , solve for t, obtaining t= v ? vo a .. †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. ( 1. 9. 4 ) †¢ Substituting equation ( 1. . 4 ) into equation ( 1. 9. 3 ), we have ASD 2011/12 KINEMATICS 8/23 PPH0095 MECHANICS 2 2 ? v + v o v ? v o ? v ? v o s=? ?= 2a ? 2 a ? †¢ Solve for v 2 and obtain 2 v 2 = v o + 2as †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. ( 1. 9. 5 ) [ omit t ] †¢ From equation ( 1. 9. 1 ) , solve for vo, obtaining vo = v – at†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. (1. 9. 6) †¢ Substitute equation (1. 9. 6) into (1. 9. 2), s =( v + v ? at )t 2 or s = vt ? ? at2 †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. ( 1. 9. 3 ) [ omit vo ] Example 2:: Spotting a police car, you brake a porsche from 75 km/h to 45 km/h over a displacement of 88 m. a) What is the acceleration assumed to be constant ? Given: vo = 75km / h = 75 ? 103 = 20. 83 m/s 3600 45 ? 103 v = 45km / h = = 12. 5 m/s 3600 s = 88 m, a = ? v 2 = vo + 2a s (12. 5 m/s)2 = (20. 83 m/s)2 + 2a(88 m) a = -1. 6 m/s1 2 b) What is the elapsed time ? s = ? (vo + v)t 88 m = ? (12. 5 m/s + 20. 83 m/s)t t = 5. 4 s c) If you continue to slow down with the acceleration calculated in (a), how much time will elapse in bringing the car to rest from 75 km/h ? v = vo + at 20. 83 m/s = 12. 5 m/s + (-1. 6 m/s2 )t t = 13 s ASD 2011/12 KINEMATICS 9/23 PPH0095 MECHANICS d) In ( c ) what distance will be covered ? s = vot + ? at2 = (20. 3 m/s)(13 s) + ? (-1. 6 m/s2)(13 s)2 = 137 m e) Suppose that later, using the acceleration calculate in (a) but a different initial velocity , you bring your car to rest after travelling 200 m . What is the total braking time ? s = vt ? ? at2 200 m = (0 m/s) t – ? (-1. 6 m/s2) t2 t = 16 s 2. 10 MOTION GRAPHS †¢ The motion of a body can be illustrated by o a displacement-time ( x t ) graph. o a velocity-time ( v ) graph o an acceleration-time ( a t ) graph Displacement-time graph or s t graph of a body shows how the displacement of the body varies with time. o Instantaneous velocity, v= †¢ dx = gradient of the s – t graph. dt Figure 5 shows the x – t graphs for four types of motion. Figure 5a o Constant velocity Velocity = gradient of the graph = constant ASD 2011/12 KINEMATICS 10/23 PPH0095 MECHANICS Figure 5b o Constant acceleration with initial velocity u = 0 When t = 0, gradient = 0 Gradient increases as t increases ? Velocity increases Figure 5c o Constant acceleration with initial velocity u ? 0 When t = 0, gradient ? 0 hence initial velocity ? 0 Gradient increases as t increases ? Velocity increases ASD 2011/12 KINEMATICS 11/23 PPH0095 MECHANICS Figure 5d †¢ Non-uniform acceleration When t = 0, gradient ? 0 Hence initial velocity ? 0 When t = t, gradient = 0 Hence velocity = 0 When t = t2, gradient ; 0, Hence velocity is negative. When vel ocity is negative, object is moving in the opposite direction. Velocity–time graph or v – t graph of a body shows how the velocity of a body varies with time. Velocity, v = dx dt Displacement, s = ? v dt = area under the v – t graph. Instantaneous acceleration, a = †¢ dv = gradient of the v t graph at that instant. dt Figure 6 shows the v – t graphs for six types of motion. ASD 2011/12 KINEMATICS 12/23 PPH0095 MECHANICS Figure 6a Uniform velocity Gradient = 0, acceleration = 0 Displacement from t = t1 to t = t2, s = shaded area , A Figure 6b o Uniform acceleration Initial velocity = 0 Gradient = constant, hence Acceleration = constant Displacement from t = t1 to t = t2, s = shaded area , A ASD 2011/12 KINEMATICS 13/23 PPH0095 MECHANICS Figure 6c o Uniform acceleration Initial velocity ? 0 Gradient = constant, hence Acceleration = constant Displacement from t = t1 to t = t2, s = shaded area , A Figure 6d o Uniform acceleration Initial velocity ? 0 Co nstant negative gradient implies constant negative acceleration (constant deceleration) ASD 2011/12 KINEMATICS 14/23 PPH0095 MECHANICS Figure 6e o Non-uniform velocity Initial velocity = 0 Gradient decreases, hence acceleration decreases, Displacement from t = t1 to t = t2, s = shaded area , A Figure 6f o Increasing acceleration Initial velocity = 0 Gradient increases, hence acceleration increases. †¢ Acceleration-time graph or a – t graph of a body shows how the acceleration of the body varies with time. dv a = dt Increase in velocity = ? a dt = area under the a – t graph. Figure 7 shows four acceleration–time graphs. †¢ ASD 2011/12 KINEMATICS 15/23 PPH0095 MECHANICS Figure 7a o Constant acceleration Gradient=constant Area, A = increase in velocity from t = t1 to t = t2 Figure 7b o Acceleration increases uniformly Gradient=constant Area, A = increase in velocity from t = t1 to t = t2 Figure 7c o Decreasing acceleration Area, A = decreasing in velocity from t = t1 to t = t2 ASD 2011/12 KINEMATICS 16/23 PPH0095 MECHANICS Figure 7d o Uniform velocity When velocity = constant, acceleration , a = 0 2. 11 FREE FALLING OBJECTS UNDER GRAVITY †¢ †¢ †¢ †¢ †¢ †¢ †¢ †¢ †¢ †¢ Any object moving freely under the influence of gravity, regardless of its initial motion. When an object is in free fall, we assume that air resistance is negligible and that the only force acting on it is gravity. Object thrown upward/downward, will both experience the same acceleration as an object released from rest. Assuming air resistance is negligible, the rate of acceleration (g) of all objects in free fall is approximately 9. 8 m/s2. The vertical motion of a freely falling object is equivalent to motion in one dimension under constant acceleration. The equations for uniformly accelerated motion can be applied to free fall. Since the motion is vertical, y replaces x and y0 replaces x0 while g replaces the symbol a. It is arbitrary whether we choose y to be positive in the upward or downward direction; but we must be consistent about it throughout a problem’s solution. Thrown downward: a = g = +9. 80 m/s2 Thrown upward: a = g = -9. 80 m/s2 For example: When a ball is thrown vertically upwards, its velocity decreases as it rises because the acceleration of free fall is in the opposite direction to the motion. If the upward direction is assumed to be positive, then the acceleration a = 9. 8 m/s2. When the ball reaches the maximum height, o The velocity v = 0, and o The acceleration a = -9. 0 m/s2 Figure 8 shows the graphs for the motion of the ball. †¢ ASD 2011/12 KINEMATICS 17/23 PPH0095 MECHANICS Figure 8 †¢ Equations for free-fall acceleration: o v = v o + gt o y = (v + v o )t o y = vo t + gt 2 o y = vt 1 gt 2 2 1 2 1 2 o v = v o + 2gy 2 Example 3: A boy on a bridge throws a stone vertically downward toward the river below with an initial velocity of 14. 7 m/s . If the stone hits the water 2. 00 s later, what is the height of the bridge above the water? Solution: Take y as positive downward Given: v0 = 14. 7 m/s , ( downward) , t = 2. 00 s and g = + 9. 8 m/s/s 1 y y o = v o t + at 2 2 = (14. )(2. 00) + (1 / 2)(9. 8)(2. 00) 2 = 29. 4 + 19. 60 y = 49. 0 m 2. 12 PROJECTILE MOTION †¢ †¢ It is the motion in two dimensions under the action of gravity only (downward) We Can study the motion of a projectile by considering ASD 2011/12 KINEMATICS 18/23 PPH0095 MECHANICS †¢ †¢ o The vertical component. And o The horizontal component of the motion. The vertical component of motion is motion under uniform acceleration. The horizontal component of motion is motion under uniform velocity If air resistance is negligible, then the horizontal component of motion does not change; thus ax = 0 and vx = vx0 = constant. The vertical component of motion is affected by gravity and is described by the equations for an object in free fall. To describe it, choose a suitable origin, O and the axes (Figure 9). Let vo denote the initial velocity and ? the angle between vo and the positive x-axis. †¢ Figure 9 †¢ From diagram, the motion can divide in two components, horizontal (x-axis) and vertical (y-axis). Two assumptions: o The free-fall acceleration, g is constant over the range of the motion and is directed downward. (-g) o The effect of air resistance is negligible that is the horizontal motion has zero acceleration. x-component 0 vxo = vocos? 0 = 0 vx x y-component -g vyo = vosin? yo = 0 vy y Acceleration Initial velocity Initial position Velocity Position ASD 2011/12 KINEMATICS 19/23 PPH0095 MECHANICS From this, one can show that: Vertical component (y-component): Vertical velocity component: v y = v yo gt = v o sin ? gt Vertical position component: 1 1 y = v yo t gt 2 = (v o sin ? )t g t 2 2 2 *from v = vo + at *from y = v o t + 1 2 at 2 †¢ At maximum Height, H, the vy = 0. 2 From, v = vo + 2a y 2 0 = (v o sin ? ) 2 ? 2 gH H= v0 sin 2 ? 2g 2 If T is the time taken from O to A, to find the T, y = 0, t = T From, y = v o t + 1 2 at 2 1 gT 2 2 0 = (v o sin ? T ? T = 2v o sin ? g Horizontal component (y-component): Horizontal velocity component : vx = vxo = vo cos ? Horizontal position component : x = vxot = (vo cos ? )t To find the horizontal Range, R, t = T, x = R ASD 2011/12 KINEMATICS 20/23 PPH0095 MECHANICS From x = vo t + 1 2 at ,a =0 2 ? 2v sin ? ? ? R = (v o cos ? )? o ? ? g ? ? R= v o sin 2? g The maximum horizontal range is achieved when ? = 45o. At any time the distance, r of the projectile from the origin is r = x 2 + y2 By eliminate, the trajectory (the relation between x and y) is a parabola, Vertical position component : y = (v o sin ? )t †¢ 1 2 gt 2 Horizontal position component : x = (vo cos ? ) t x t = v o cos ? ? x ? 1 ? x ? y = (vo sin ? )? ? v cos ? ? ? 2 g ? v cos ? ? ? ? ? ? o ? ? o ? g x2 = (tan ? )x ? 2 2 2vo cos ? = x tan ? ? gx 2 sec 2 ? 2 2v 2 gx 2 y = x tan ? ? 2 (1 + tan 2 ? ) 2v ASD 2011/12 KINEMATICS 21/23 PPH0095 MECHANICS †¢ Since sin 2? = sin (180o 2? ), there would be two angles of projection, ? and (90o- ? ), that would achieve a particular range R for a certain speed of projection vo . For the speed of projection vo , however, the maximum range is obtained only when the angle of projection is 45o as shown in Figure 10. Figure 10 2. 13 UNIFORM CIRCULAR MOTION An object that moves in a circle at constant speed is said to experience uniform circular motion where the magnitude of velocity remains constant the direction of velocity continuously change †¢ Acceleration is defined as the rate of change of velocity. The rate of change of velocity depends on the change in direction as well as the change in the magnitude. Therefore, object revolving in a circle is continuously accelerating (even when the speed remains constant). An object moving in a circle of radius r with constant speed v, has an acceleration whose direction is toward the center of the circle and whose magnitude is given by the formula 2 †¢ aR = (Please refer to text book section 5. 2, pages 120, how to get this equation) v r ASD 2011/12 KINEMATICS 22/23 PPH0095 MECHANICS v1 aR aR v1 Figure 11 †¢ †¢ †¢ The acceleration vector always points toward the center of the circle. The velocity vector always points in the direction of motion (tangent to the circle or perpendicular to the radius of the circle). Circular motion is often described in terms of the frequency f as so many revolutions per second. The period T of an object revolving in a circle is the time required for one complete revolution. T= 1 f v= 2? r T END OF CHAPTER 2. ASD 2011/12 KINEMATICS 23/23