Assignment One Suggested Due Date: July 17th In this assignment you will read three articles You will answer questions about Hayek, Lucas, and Mankiw et. al. which consider just those particular articles. Then at the end of the assignment there is a cluster of questions that deal with both Lucas and Mankiw et al where you will have an opportunity to compare and contrast those two articles. When you have completed the assignment, place it in the appropriate drop box in WTClass. Hayek: The Use of Knowledge in Society http://www.econlib.org/library/Essays/hykKnw1.html Adapted from Michael K. Salemi “The Use of Knowledge in Society” F. A. Hayek Discussion Questions 1.1. “The peculiar character of the problem of a rational economic order is determined precisely by the fact that the knowledge of the circumstances of which we must make use never exists in concentrated or integrated form, but solely as the dispersed bits of incomplete and frequently contradictory knowledge which all the separate individuals possess (H.3)” a. What does Hayek mean by a “rational economic order”? b. What does Hayek mean by “dispersed bits of incomplete and frequently contradictory knowledge”? c. Why is Hayek critical of the common assumptions in economic analysis that buyers, sellers, producers and the economist all know every relevant thing about the economy? d. What, in summary, does Hayek mean by the quoted statement? 1.2. What, according to Hayek, is the information needed to operate effectively in a complex market economy? a. What does Hayek mean by “planning”? b. What is the minimum information needed by economic planners and individuals? c. Does the minimum differ for planners and for individuals? How? Why? d. What happens when some individuals possess more information than other individuals? e. What does Hayek mean when he says (H.16) “…the sort of knowledge with which I have been concerned is knowledge of the kind which by its nature cannot enter into statistics and therefore cannot be conveyed to any central authority in statistical form”? f. Why, according to Hayek, can the “information problem” be solved by “the price system”? 1.3. Why, according to Hayek, is the true function of the price system the communication of information? a. Why does Hayek use the term ‘marvel’ in his discussion of the economy of knowledge? b. What does Hayek mean when he says (H.26) “…man has been able to develop that division of labor on which our civilization is based because he happened to stumble upon a method which made it possible”? Read Robert Lucas’ “Some Macroeconomics for the 21st Century” in the Journal of Economic Perspectives. (Skip the appendix.) All four of these links go to the same article. Some of the links might not be accessible to you, but I think that at least one of them should work for all of you. https://www.aeaweb.org/articles.php?doi=10.1257/jep.14.1.159 http://www.jstor.org/stable/2647059 http://www.econ.psu.edu/~aur10/Econ%20570%20Fall%202009/Lucas%20JEP%202000.pdf http://faculty.georgetown.edu/mh5/class/econ102/readings/Macro_21st_Century.pdf 1. According to Lucas, why has the world’s economy grown so much since 1960? 2. According to Lucas, why do some nations grow faster than others? 3. According to Lucas, why will growth and inequality decrease in the next 100 years? 4. Is Lucas’ model in this paper “economics?” Read Greg Mankiw, Romer and Wiel’s article in The Quarterly Journal of Economics. http://www.econ.nyu.edu/user/debraj/Courses/Readings/MankiwRomerWeil.pdf 1. Many economists think the Solow Growth Model is of limited use. (One of my professors at OU stated that it took economists 50 years to figure out that their growth model has nothing to do with growth.) But does the Solow model give “…the right answer to the questions it is designed to address?” 2. Why is human capital important when testing the Solow model against the data? 3. Explain how the authors conclude that the incomes of the world’s nations are converging? Now that you’ve answered questions about Lucas and Mankiw et al separately, consider this question: Both of these papers develop the notion that the economies of the world’s nations will tend to “converge” over time. Compare and contrast the way(s) in which the papers advance the idea of convergence. Assignment Two Due Date July 24th This assignment is very straight forward. You’ll read two papers and answer questions about each of them. Read Krugman’s paper on unemployment http://www.kc.frb.org/PUBLICAT/ECONREV/EconRevArchive/1994/4Q94KRUG.pdf 1. What is the difference between structural and cyclical unemployment? In this context, what is the difference between Europe and the US? What is the evidence that Krugman uses to back his opinion? 2. What is the natural rate of unemployment? Why is it higher/rising in Europe? Again, what is the evidence? 3. What is the relationship between the rising unemployment in Europe and the rise in inequality in the US. (What does Krugman mean by inequality?) 4. What is NOT to blame for either the rise in unemployment or inequality? 5. What policies, if any, can be put into place to combat rising inequality/unemployment? 6. Are you convinced by Krugman’s argument which rules out globalization as the likely cause for high European unemployment and high US wage inequality? 7. Consider Table 2 in Krugman. Why does Krugman include Table 2 in his paper? In other words, what point is strengthened by the data in Table 2 and why is it crucial to Krugman’s larger thesis? NOW, recreate the data for Table 2 for either the UK or US for the latest year possible. Has anything changed as a result of the Great Recession? Read Thomas Sargent’s paper about the credibility of “Reaganonomics.” http://minneapolisfed.contentdm.oclc.org/cdm/ref/collection/p15334coll1/id/366 http://minneapolisfed.contentdm.oclc.org/cdm/singleitem/collection/p15334coll1/id/366/rec/1 You might like this: http://www.ispot.tv/ad/7Lj9/ally-bank-predictions-featuring-thomas-sargent 1. What is a dynamic game? 2. Why should we think of monetary and fiscal policy as dynamic game? Who are the players and what are the strategies? 3. When are government budgets inflationary? (Again, think in terms of a game.) 4. What are the consequences if the monetary authority does not coordinate with fiscal policy agents? 5. Has Sargent done of good job characterizing the interplay between policymakers in the government, the central bank, and the public? 6. What is the connection between policy coordination and credibility? 7. Why, according to Sargent, were Reagan’s fiscal and monetary policy regimes “incredible?” Explain carefully. Assignment Three Due Date July 31 Read Taylor, Miskin, Obstfeld and Rogoff. Answer the questions for each article, then answer the final cluster that requires you to consider Miskin, Obstfeld and Rogoff. Suggested due date: January 2nd. Read John Taylor’s article about monetary transmission mechanisms. http://web.econ.unito.it/bagliano/ecmon_readings/taylor_jep95.pdf Also, to understand traditional monetary policy, listen to this: http://www.econtalk.org/archives/2008/08/john_taylor_on.html These questions refer to the article, not the podcast. 1. How does monetary policy (or changes in monetary policy) affect output and inflation? In other words, what is the monetary policy transmission mechanism? 2. What is the importance of financial market prices in Taylor’s view? 3. What is the importance of rational expectations and rigidities in the prices of labor and goods? 4. What is a reaction function? Why is a reaction function important? 5. What is an “optimal monetary policy rule?” 6. Has the monetary transmission mechanism changed? How? 7. What are the criticisms of Taylor’s views? How does he respond? What do you think? Read Mishkin’s article about global financial instability. http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.13.4.3 1. What is a financial crisis? 2. How did adverse selection and moral hazard contribute to the financial crisis in Mexico and East Asia in the 1990s? What are adverse selection and moral hazard? 3. Did irresponsible monetary and fiscal policy contribute to the crisis in the 90s? Why or why not? 4. How is it possible for the IMF to help in a crisis when a domestic central bank might not be able to help. 5. What should the US learn (or have learned??) from the crisis in the 90s? Read Rogoff’s article about global financial instability. http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.13.4.21 http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.13.4.21 Answer the questions and place the answers in the appropriate drop box in WTClass. 1. According to Rogoff, is the status quo in international lending viable or not? Explain. 2. Can the IMF handle international financial crises? Why or why not? 3. Rogoff gives six solutions to save the global financial system (deep pockets lender of last resort, an international financial crisis manager, an international bankruptcy court, an international regulator, international deposit insurance corporation, and a world monetary authority.) What is wrong with all of these? 4. Can developing economies cope with speculative capital flows without help? Explain. 5. What will be (should be) the role that equity financing play in developing country projects? Read Obstfeld on Global Capital Markets: http://www.nber.org/papers/w6559.pdf 1. Look at table 1 and figure 1. How does Obstfeld use the data in that table to suggest that 1) markets became less open then more open in the 20th century. 2. What is the “openness trilemma?” What are the economic and/or policy trade-offs with having a global, open and integrated financial system? 3. How does economic integration impact a nation’s ability to tax capital? Can you think of some high profile cases in the news lately that illustrate this fact? (Hint: you should be able to.) 4. What is the international diversification puzzle? What market failures have arisen (if any) have arisen due to more integration and openness? Comparing Obstfeld, Miskin, and Rogoff 1. Would the authors’ advice about policies to reduce the costs of financial integration be the same? Why or why not? 2. Would the authors’ agree that we need an international regulatory body to stave off international financial crises? Why or why not? 3. What is your opinion? Is it good to have a global financial market? Why or why not? Assignment Four Due Date August 7 Straight forward assignment: Read and answer the questions. Read Arnold Kling’s history of the policies that created the great recession http://mercatus.org/publication/not-what-they-had-mind-history-policies-produced-financial-crisis-2008 1. Using only the executive summary, what does Kling think caused the Financial Crisis of 2008? (Use only one sentence.) 2. One page 5, what is “the fact?” and what does this “fact” mean to you? 3. Briefly summarize the four components of the Financial Crisis? 4. On page 10, Kling states, “These property bubbles (in the U.K. and Spain) cannot be blamed on U.S. policy.” How confident are you on that point? Is Kling wrong? 5. Kling’s matrix of causes, gives almost all weight to what two factors? What three factors are almost completely not responsible? 6. Many have blamed designer financial (my term) like CDS and CDO and the shadow banking system for the collapse. How do these fit into Kling’s narrative? 7. Outline the progression of policy that caused/responded to economic conditions in the 30s, 70s and 80s and 00s. 8. What role did the mortgage interest deduction have on housing market? 9. What institution invented and allowed the expansion of mortgage-backed securities? 10. What is regulatory arbitrage? 11. Why did the Basel agreement create an advantage for mortgage securitization? 12. Did the Federal Reserve (and presumably other regulatory agencies know and even encourage regulatory capital arbitrage? What author does Kling cite to establish this? 13. What did the 2002 modification of the Basel Rules do to capital requirements? (See figure 4) 14. Summarize the Shadow Regulatory Committee’s statement 160. 15. Did non market institutions, such as the IMF and Bernanke, think, in 2006, that financial innovation had make the banking sector more or less fragile? 16. What is time inconsistency? (You can look this up elsewhere.) 17. How might “barriers to entry” by related to “safety and soundness?” 18. A Curmudgeon is an old man who is easily annoyed and angered. He also complains a lot. (I had to look it up.) I think I’ll change my xbox gamertag to this word, but I’ll bet it is taken. 19. How did credit scoring and credit default swaps enlarge the mortgage securities market? 20. Why, up until 2007, did we think that monetary expansion was all that was needed to mitigate the impact of financial crises? 21. Suppose that financial markets are inherently unstable. What does this mean are two goals of regulation and regulators? 22. Why are type two errors so problematic? (Two reasons.) 23. How could we make the banking sector easy to fix? Assignment Five Due August 13 Read the linked lectures and answer the questions. Lecture 1 http://econlog.econlib.org/archives/2008/11/lectures_in_mac.html 1.1 Why do you think macroeconomic realities must be reconciled with microeconomic analysis? (This is not a rhetorical question, but it will be hard for you to answer. There is no “wrong” answer you could give. Just think about it for a few minutes.) Lecture 2 http://econlog.econlib.org/archives/2008/11/lectures_in_mac_1.html 2.1 Consider this article after you have read Hayek. How do prices and wages perform the function of “central planning?” 2.2 Kling makes that claim that, because most workers do not do manual labor anymore, the economy is different that it was in 1930. Assuming he is correct, do you think central planning would be harder today or easier? Why? Lecture 3 http://econlog.econlib.org/archives/2008/11/lectures_on_mac.html 3.1 Give a one sentence definition of structural unemployment, of frictional unemployment and of cyclical unemployment. Lecture 4 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_1.html 4.1 So, why does the economy adjust employment rather than wages? Lecture 5 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_2.html 5.1 Kling gives 5 reasons the DotCom recession was worse than the previous two recessions (at least in duration). Which reason do you think is the most compelling? Lecture 6 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_3.html 6.1 Why are Keynesian remedies (blunt fiscal and monetary policy measures) less appropriate in a post industrial economy, according to Kling? Lecture 7 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_4.html 7.1 Why is it so hard to separate finance and government, according to Kling? Lecture 8 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_5.html 8.1 Why is American Express Travelers Checks so interesting? Do credit cards work in a similar way? (I really don’t know the answer to this one. I just know that credit cards have made travelers checks obsolete.) Lecture 9. http://econlog.econlib.org/archives/2008/12/lectures_on_mac_6.html 9.1 According to this article, why do we have banks (financial sector or financial intermediation?) Lecture 10 http://econlog.econlib.org/archives/2008/12/lectures_on_mac_7.html 10.1 Why are banks better than barter, according to this leture? 10.2 Politics tends to favor bailouts of failed firms. Why is this exactly wrong?

Assignment One Suggested Due Date: July 17th In this assignment you will read three articles You will answer questions about Hayek, Lucas, and Mankiw et. al. which consider just those particular articles. Then at the end of the assignment there is a cluster of questions that deal with both Lucas and Mankiw et al where you will have an opportunity to compare and contrast those two articles. When you have completed the assignment, place it in the appropriate drop box in WTClass. Hayek: The Use of Knowledge in Society http://www.econlib.org/library/Essays/hykKnw1.html Adapted from Michael K. Salemi “The Use of Knowledge in Society” F. A. Hayek Discussion Questions 1.1. “The peculiar character of the problem of a rational economic order is determined precisely by the fact that the knowledge of the circumstances of which we must make use never exists in concentrated or integrated form, but solely as the dispersed bits of incomplete and frequently contradictory knowledge which all the separate individuals possess (H.3)” a. What does Hayek mean by a “rational economic order”? b. What does Hayek mean by “dispersed bits of incomplete and frequently contradictory knowledge”? c. Why is Hayek critical of the common assumptions in economic analysis that buyers, sellers, producers and the economist all know every relevant thing about the economy? d. What, in summary, does Hayek mean by the quoted statement? 1.2. What, according to Hayek, is the information needed to operate effectively in a complex market economy? a. What does Hayek mean by “planning”? b. What is the minimum information needed by economic planners and individuals? c. Does the minimum differ for planners and for individuals? How? Why? d. What happens when some individuals possess more information than other individuals? e. What does Hayek mean when he says (H.16) “…the sort of knowledge with which I have been concerned is knowledge of the kind which by its nature cannot enter into statistics and therefore cannot be conveyed to any central authority in statistical form”? f. Why, according to Hayek, can the “information problem” be solved by “the price system”? 1.3. Why, according to Hayek, is the true function of the price system the communication of information? a. Why does Hayek use the term ‘marvel’ in his discussion of the economy of knowledge? b. What does Hayek mean when he says (H.26) “…man has been able to develop that division of labor on which our civilization is based because he happened to stumble upon a method which made it possible”? Read Robert Lucas’ “Some Macroeconomics for the 21st Century” in the Journal of Economic Perspectives. (Skip the appendix.) All four of these links go to the same article. Some of the links might not be accessible to you, but I think that at least one of them should work for all of you. https://www.aeaweb.org/articles.php?doi=10.1257/jep.14.1.159 http://www.jstor.org/stable/2647059 http://www.econ.psu.edu/~aur10/Econ%20570%20Fall%202009/Lucas%20JEP%202000.pdf http://faculty.georgetown.edu/mh5/class/econ102/readings/Macro_21st_Century.pdf 1. According to Lucas, why has the world’s economy grown so much since 1960? 2. According to Lucas, why do some nations grow faster than others? 3. According to Lucas, why will growth and inequality decrease in the next 100 years? 4. Is Lucas’ model in this paper “economics?” Read Greg Mankiw, Romer and Wiel’s article in The Quarterly Journal of Economics. http://www.econ.nyu.edu/user/debraj/Courses/Readings/MankiwRomerWeil.pdf 1. Many economists think the Solow Growth Model is of limited use. (One of my professors at OU stated that it took economists 50 years to figure out that their growth model has nothing to do with growth.) But does the Solow model give “…the right answer to the questions it is designed to address?” 2. Why is human capital important when testing the Solow model against the data? 3. Explain how the authors conclude that the incomes of the world’s nations are converging? Now that you’ve answered questions about Lucas and Mankiw et al separately, consider this question: Both of these papers develop the notion that the economies of the world’s nations will tend to “converge” over time. Compare and contrast the way(s) in which the papers advance the idea of convergence. Assignment Two Due Date July 24th This assignment is very straight forward. You’ll read two papers and answer questions about each of them. Read Krugman’s paper on unemployment http://www.kc.frb.org/PUBLICAT/ECONREV/EconRevArchive/1994/4Q94KRUG.pdf 1. What is the difference between structural and cyclical unemployment? In this context, what is the difference between Europe and the US? What is the evidence that Krugman uses to back his opinion? 2. What is the natural rate of unemployment? Why is it higher/rising in Europe? Again, what is the evidence? 3. What is the relationship between the rising unemployment in Europe and the rise in inequality in the US. (What does Krugman mean by inequality?) 4. What is NOT to blame for either the rise in unemployment or inequality? 5. What policies, if any, can be put into place to combat rising inequality/unemployment? 6. Are you convinced by Krugman’s argument which rules out globalization as the likely cause for high European unemployment and high US wage inequality? 7. Consider Table 2 in Krugman. Why does Krugman include Table 2 in his paper? In other words, what point is strengthened by the data in Table 2 and why is it crucial to Krugman’s larger thesis? NOW, recreate the data for Table 2 for either the UK or US for the latest year possible. Has anything changed as a result of the Great Recession? Read Thomas Sargent’s paper about the credibility of “Reaganonomics.” http://minneapolisfed.contentdm.oclc.org/cdm/ref/collection/p15334coll1/id/366 http://minneapolisfed.contentdm.oclc.org/cdm/singleitem/collection/p15334coll1/id/366/rec/1 You might like this: http://www.ispot.tv/ad/7Lj9/ally-bank-predictions-featuring-thomas-sargent 1. What is a dynamic game? 2. Why should we think of monetary and fiscal policy as dynamic game? Who are the players and what are the strategies? 3. When are government budgets inflationary? (Again, think in terms of a game.) 4. What are the consequences if the monetary authority does not coordinate with fiscal policy agents? 5. Has Sargent done of good job characterizing the interplay between policymakers in the government, the central bank, and the public? 6. What is the connection between policy coordination and credibility? 7. Why, according to Sargent, were Reagan’s fiscal and monetary policy regimes “incredible?” Explain carefully. Assignment Three Due Date July 31 Read Taylor, Miskin, Obstfeld and Rogoff. Answer the questions for each article, then answer the final cluster that requires you to consider Miskin, Obstfeld and Rogoff. Suggested due date: January 2nd. Read John Taylor’s article about monetary transmission mechanisms. http://web.econ.unito.it/bagliano/ecmon_readings/taylor_jep95.pdf Also, to understand traditional monetary policy, listen to this: http://www.econtalk.org/archives/2008/08/john_taylor_on.html These questions refer to the article, not the podcast. 1. How does monetary policy (or changes in monetary policy) affect output and inflation? In other words, what is the monetary policy transmission mechanism? 2. What is the importance of financial market prices in Taylor’s view? 3. What is the importance of rational expectations and rigidities in the prices of labor and goods? 4. What is a reaction function? Why is a reaction function important? 5. What is an “optimal monetary policy rule?” 6. Has the monetary transmission mechanism changed? How? 7. What are the criticisms of Taylor’s views? How does he respond? What do you think? Read Mishkin’s article about global financial instability. http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.13.4.3 1. What is a financial crisis? 2. How did adverse selection and moral hazard contribute to the financial crisis in Mexico and East Asia in the 1990s? What are adverse selection and moral hazard? 3. Did irresponsible monetary and fiscal policy contribute to the crisis in the 90s? Why or why not? 4. How is it possible for the IMF to help in a crisis when a domestic central bank might not be able to help. 5. What should the US learn (or have learned??) from the crisis in the 90s? Read Rogoff’s article about global financial instability. http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.13.4.21 http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.13.4.21 Answer the questions and place the answers in the appropriate drop box in WTClass. 1. According to Rogoff, is the status quo in international lending viable or not? Explain. 2. Can the IMF handle international financial crises? Why or why not? 3. Rogoff gives six solutions to save the global financial system (deep pockets lender of last resort, an international financial crisis manager, an international bankruptcy court, an international regulator, international deposit insurance corporation, and a world monetary authority.) What is wrong with all of these? 4. Can developing economies cope with speculative capital flows without help? Explain. 5. What will be (should be) the role that equity financing play in developing country projects? Read Obstfeld on Global Capital Markets: http://www.nber.org/papers/w6559.pdf 1. Look at table 1 and figure 1. How does Obstfeld use the data in that table to suggest that 1) markets became less open then more open in the 20th century. 2. What is the “openness trilemma?” What are the economic and/or policy trade-offs with having a global, open and integrated financial system? 3. How does economic integration impact a nation’s ability to tax capital? Can you think of some high profile cases in the news lately that illustrate this fact? (Hint: you should be able to.) 4. What is the international diversification puzzle? What market failures have arisen (if any) have arisen due to more integration and openness? Comparing Obstfeld, Miskin, and Rogoff 1. Would the authors’ advice about policies to reduce the costs of financial integration be the same? Why or why not? 2. Would the authors’ agree that we need an international regulatory body to stave off international financial crises? Why or why not? 3. What is your opinion? Is it good to have a global financial market? Why or why not? Assignment Four Due Date August 7 Straight forward assignment: Read and answer the questions. Read Arnold Kling’s history of the policies that created the great recession http://mercatus.org/publication/not-what-they-had-mind-history-policies-produced-financial-crisis-2008 1. Using only the executive summary, what does Kling think caused the Financial Crisis of 2008? (Use only one sentence.) 2. One page 5, what is “the fact?” and what does this “fact” mean to you? 3. Briefly summarize the four components of the Financial Crisis? 4. On page 10, Kling states, “These property bubbles (in the U.K. and Spain) cannot be blamed on U.S. policy.” How confident are you on that point? Is Kling wrong? 5. Kling’s matrix of causes, gives almost all weight to what two factors? What three factors are almost completely not responsible? 6. Many have blamed designer financial (my term) like CDS and CDO and the shadow banking system for the collapse. How do these fit into Kling’s narrative? 7. Outline the progression of policy that caused/responded to economic conditions in the 30s, 70s and 80s and 00s. 8. What role did the mortgage interest deduction have on housing market? 9. What institution invented and allowed the expansion of mortgage-backed securities? 10. What is regulatory arbitrage? 11. Why did the Basel agreement create an advantage for mortgage securitization? 12. Did the Federal Reserve (and presumably other regulatory agencies know and even encourage regulatory capital arbitrage? What author does Kling cite to establish this? 13. What did the 2002 modification of the Basel Rules do to capital requirements? (See figure 4) 14. Summarize the Shadow Regulatory Committee’s statement 160. 15. Did non market institutions, such as the IMF and Bernanke, think, in 2006, that financial innovation had make the banking sector more or less fragile? 16. What is time inconsistency? (You can look this up elsewhere.) 17. How might “barriers to entry” by related to “safety and soundness?” 18. A Curmudgeon is an old man who is easily annoyed and angered. He also complains a lot. (I had to look it up.) I think I’ll change my xbox gamertag to this word, but I’ll bet it is taken. 19. How did credit scoring and credit default swaps enlarge the mortgage securities market? 20. Why, up until 2007, did we think that monetary expansion was all that was needed to mitigate the impact of financial crises? 21. Suppose that financial markets are inherently unstable. What does this mean are two goals of regulation and regulators? 22. Why are type two errors so problematic? (Two reasons.) 23. How could we make the banking sector easy to fix? Assignment Five Due August 13 Read the linked lectures and answer the questions. Lecture 1 http://econlog.econlib.org/archives/2008/11/lectures_in_mac.html 1.1 Why do you think macroeconomic realities must be reconciled with microeconomic analysis? (This is not a rhetorical question, but it will be hard for you to answer. There is no “wrong” answer you could give. Just think about it for a few minutes.) Lecture 2 http://econlog.econlib.org/archives/2008/11/lectures_in_mac_1.html 2.1 Consider this article after you have read Hayek. How do prices and wages perform the function of “central planning?” 2.2 Kling makes that claim that, because most workers do not do manual labor anymore, the economy is different that it was in 1930. Assuming he is correct, do you think central planning would be harder today or easier? Why? Lecture 3 http://econlog.econlib.org/archives/2008/11/lectures_on_mac.html 3.1 Give a one sentence definition of structural unemployment, of frictional unemployment and of cyclical unemployment. Lecture 4 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_1.html 4.1 So, why does the economy adjust employment rather than wages? Lecture 5 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_2.html 5.1 Kling gives 5 reasons the DotCom recession was worse than the previous two recessions (at least in duration). Which reason do you think is the most compelling? Lecture 6 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_3.html 6.1 Why are Keynesian remedies (blunt fiscal and monetary policy measures) less appropriate in a post industrial economy, according to Kling? Lecture 7 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_4.html 7.1 Why is it so hard to separate finance and government, according to Kling? Lecture 8 http://econlog.econlib.org/archives/2008/11/lectures_on_mac_5.html 8.1 Why is American Express Travelers Checks so interesting? Do credit cards work in a similar way? (I really don’t know the answer to this one. I just know that credit cards have made travelers checks obsolete.) Lecture 9. http://econlog.econlib.org/archives/2008/12/lectures_on_mac_6.html 9.1 According to this article, why do we have banks (financial sector or financial intermediation?) Lecture 10 http://econlog.econlib.org/archives/2008/12/lectures_on_mac_7.html 10.1 Why are banks better than barter, according to this leture? 10.2 Politics tends to favor bailouts of failed firms. Why is this exactly wrong?

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You have had the unique opportunity to develop a career plan in this academic program. By determining career goals and objectives, you should have become insightful and capable of assessing your current skills and abilities and their respective usefulness in attaining that ideal position. According to your plan, what training and education may be required before advancement is possible with respect to your future plans? What is the biggest obstacle you face in search of success?

You have had the unique opportunity to develop a career plan in this academic program. By determining career goals and objectives, you should have become insightful and capable of assessing your current skills and abilities and their respective usefulness in attaining that ideal position. According to your plan, what training and education may be required before advancement is possible with respect to your future plans? What is the biggest obstacle you face in search of success?

We can’t escape from the reality that if we wish … Read More...
5. Provide a brief discussion with supporting evidence to the following inquiry: With the responsibility of overseeing career development processes, how does management equip employees with skills that impact their performance in an efficient and effective manner?

5. Provide a brief discussion with supporting evidence to the following inquiry: With the responsibility of overseeing career development processes, how does management equip employees with skills that impact their performance in an efficient and effective manner?

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Question 3 (1 point) In Rotter’s model, the behavior that is most likely to be performed in a given situation is Question 3 options: the one that has been reinforced. the one with the strongest behavior potential. the one for which a model has been reinforced. the one most consistent with the person’s self concept. Question 4 (1 point) Marlene’s desk becomes so messy that on occasion she cannot find an important paper she is looking for. After several incidents in which she suffered the consequences of not finding a paper she needed (such as a homework assignment), she learned to organize and straighten her desk. Marlene learned this new behavior through which operant conditioning procedure? Question 4 options: positive reinforcement negative reinforcement punishment extinction Question 5 (1 point) Colleen is trying to decide which of two events to enter in the school track meet. She thinks she would have a better chance of winning in the 100 meter race, but decides to enter the 10,000 meter race instead. According to Rotter’s theory, Question 5 options: her generalized expectancies determined this decision. the reinforcement value of winning the 10,000 meter race is greater than the reinforcement value of winning the 100 meter race. the decision illustrates that the behavior potential does not always determine behavior. she must have been reinforced for winning the 10,000 meter race in the past. Page 1 of 3 ________________________________________ . Question 6 (1 point) A woman complains to her therapist that lately she hasn’t “felt like herself.” The therapist plans to use a behavior modification treatment by altering the rewards and punishments in the woman’s environment. What is likely to be the first step the therapist takes in setting up this treatment? Question 6 options: Define the woman’s problem in terms of observable behaviors. Interview people the woman knows to determine the extent of the problem. Obtain baseline data for how often and when the problem occurs. Determine what in the woman’s past has been responsible for causing this problem. Question 7 (1 point) According to Bandura, we learn many behaviors by observing models. Whether or not we perform these behaviors depends on Question 7 options: our expectations for rewards and punishments. the reinforcement value of the rewards. generalized expectancies. whether we are children or adults. Question 8 (1 point) According to Bandura, people are most likely to change their behavior when they believe Question 8 options: the therapist has the ability to change them. following the treatment program can lead to the desired outcome. they are capable of engaging in the behaviors needed to bring about the desired outcome. they have chosen the type of treatment themselves. Question 9 (1 point) From his observations of cats escaping from a “puzzle box” to obtain a piece of fish, Thorndike developed a theory that is known as Question 9 options: the law of operant conditioning. the law of effect. the law of consequences. the law of association. Question 10 (1 point) Edward Thorndike observed cats learning to escape from boxes to obtain a piece of fish. He derived from these observations the “law of effect.” This was an early statement of Question 10 options: classical conditioning. operant conditioning. shaping. stimulus generalization. ________________________________________ . Question 11 (1 point) According to the behaviorist position, why don’t classically conditioned phobias extinguish after the pairing is removed? Question 11 options: People expect that the feared object will continue to hurt them. The fear and associated behaviors, such as running away from the feared object, often are reinforced. The fear of the original object generalizes to additional objects. The feared object has lost all of its reinforcement value. Question 12 (1 point) John’s mother wants her son to stop crying every time something goes wrong. Following a psychologist’s advice, she stops running to comfort John whenever the boy starts crying over some minor incident. After a few weeks, she notices that John cries much less often than he used to. This is an example of Question 12 options: positive reinforcement. negative reinforcement. punishment. extinction. Question 13 (1 point) According to Bandura, behavior modification procedures Question 13 options: are most effective when used in conjunction with other types of treatments. provide people with a method to change themselves once they have decided to do so. are not as effective as behavior therapists claim. are no more effective than providing clients with no treatment. Question 14 (1 point) The behavioral approach to personality postulates that personality is Question 14 options: the combination of environmental circumstances and unconscious impulses. a function of how we feel about conditions in the environment. the consistent patterns of behavior we engage in. the result of inherited predispositions to behave in certain ways. Question 15 (1 point) A woman shows no interest in socializing with other people. How might a behaviorist explain this behavior? Question 15 options: The woman does not believe that she can interact effectively with other people. The woman has not been reinforced enough for engaging in social behavior. The woman experiences anxiety in social situations and uses her asocial style as a defense against this anxiety. The woman is either high in social anxiety or low in sociability.

Question 3 (1 point) In Rotter’s model, the behavior that is most likely to be performed in a given situation is Question 3 options: the one that has been reinforced. the one with the strongest behavior potential. the one for which a model has been reinforced. the one most consistent with the person’s self concept. Question 4 (1 point) Marlene’s desk becomes so messy that on occasion she cannot find an important paper she is looking for. After several incidents in which she suffered the consequences of not finding a paper she needed (such as a homework assignment), she learned to organize and straighten her desk. Marlene learned this new behavior through which operant conditioning procedure? Question 4 options: positive reinforcement negative reinforcement punishment extinction Question 5 (1 point) Colleen is trying to decide which of two events to enter in the school track meet. She thinks she would have a better chance of winning in the 100 meter race, but decides to enter the 10,000 meter race instead. According to Rotter’s theory, Question 5 options: her generalized expectancies determined this decision. the reinforcement value of winning the 10,000 meter race is greater than the reinforcement value of winning the 100 meter race. the decision illustrates that the behavior potential does not always determine behavior. she must have been reinforced for winning the 10,000 meter race in the past. Page 1 of 3 ________________________________________ . Question 6 (1 point) A woman complains to her therapist that lately she hasn’t “felt like herself.” The therapist plans to use a behavior modification treatment by altering the rewards and punishments in the woman’s environment. What is likely to be the first step the therapist takes in setting up this treatment? Question 6 options: Define the woman’s problem in terms of observable behaviors. Interview people the woman knows to determine the extent of the problem. Obtain baseline data for how often and when the problem occurs. Determine what in the woman’s past has been responsible for causing this problem. Question 7 (1 point) According to Bandura, we learn many behaviors by observing models. Whether or not we perform these behaviors depends on Question 7 options: our expectations for rewards and punishments. the reinforcement value of the rewards. generalized expectancies. whether we are children or adults. Question 8 (1 point) According to Bandura, people are most likely to change their behavior when they believe Question 8 options: the therapist has the ability to change them. following the treatment program can lead to the desired outcome. they are capable of engaging in the behaviors needed to bring about the desired outcome. they have chosen the type of treatment themselves. Question 9 (1 point) From his observations of cats escaping from a “puzzle box” to obtain a piece of fish, Thorndike developed a theory that is known as Question 9 options: the law of operant conditioning. the law of effect. the law of consequences. the law of association. Question 10 (1 point) Edward Thorndike observed cats learning to escape from boxes to obtain a piece of fish. He derived from these observations the “law of effect.” This was an early statement of Question 10 options: classical conditioning. operant conditioning. shaping. stimulus generalization. ________________________________________ . Question 11 (1 point) According to the behaviorist position, why don’t classically conditioned phobias extinguish after the pairing is removed? Question 11 options: People expect that the feared object will continue to hurt them. The fear and associated behaviors, such as running away from the feared object, often are reinforced. The fear of the original object generalizes to additional objects. The feared object has lost all of its reinforcement value. Question 12 (1 point) John’s mother wants her son to stop crying every time something goes wrong. Following a psychologist’s advice, she stops running to comfort John whenever the boy starts crying over some minor incident. After a few weeks, she notices that John cries much less often than he used to. This is an example of Question 12 options: positive reinforcement. negative reinforcement. punishment. extinction. Question 13 (1 point) According to Bandura, behavior modification procedures Question 13 options: are most effective when used in conjunction with other types of treatments. provide people with a method to change themselves once they have decided to do so. are not as effective as behavior therapists claim. are no more effective than providing clients with no treatment. Question 14 (1 point) The behavioral approach to personality postulates that personality is Question 14 options: the combination of environmental circumstances and unconscious impulses. a function of how we feel about conditions in the environment. the consistent patterns of behavior we engage in. the result of inherited predispositions to behave in certain ways. Question 15 (1 point) A woman shows no interest in socializing with other people. How might a behaviorist explain this behavior? Question 15 options: The woman does not believe that she can interact effectively with other people. The woman has not been reinforced enough for engaging in social behavior. The woman experiences anxiety in social situations and uses her asocial style as a defense against this anxiety. The woman is either high in social anxiety or low in sociability.

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In case the body have to stay in lower temperature for extended time period (more than 1 hour), how does the body regulate its response?

In case the body have to stay in lower temperature for extended time period (more than 1 hour), how does the body regulate its response?

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http://www.econlib.org/library/Smith/smWN1.html#B.I,%20Ch.1,%20Of%20the%20Division%20of%20Labor What does Smith mean by division of labor, and how does it affect production? A. He means that each person does their own work to benefit themselves by creating goods. This creates well-crafted goods. B. He argues that in order to become more efficient, we need to put everyone in the same workhouses and eliminate division. C. He says that the division of labor provides farmers with the opportunity to become involved in manufacturing. D. He means that each person makes one small part of a good very quickly, but this is bad for the quality of production overall. E. He means that by having each individual specialize in one thing, they can work together to create products more efficiently and effectively. Which of the following is NOT an example of the circumstances by which the division of labor improves efficiency? A. A doll-making company stops allowing each employee to make one whole doll each and instead appoints each employee to create one part of the doll. B. A family of rug makers buys a loom to speed up their production. C. A mechanic opens a new shop to be nearer to the market. D. A factory changes the responsibilities of its employees so that one group handles heavy boxes and the other group does precision sewing. E. A baker who used to make a dozen cookies at a time buys a giant mixer and oven that enable him to make 20 dozen cookies at a time. Considering the global system of states, what do you think the allegory of the pins has to offer? A. It suggests that there could be a natural harmony of interests among states because they can divide labor among themselves to the benefit of everyone. B. It suggests that states can never be secure enough to cooperate because every state is equally capable of producing the same things. C. It suggests that a central authority is necessary to help states cooperate, in the same way that a manager oversees operations at a factory. D. The allegory of the pins is a great way to think about how wars come about, because states won’t cooperate with each other like pin-makers do. E. The allegory of the pins shows us that there is no natural harmony of interests between states. Smith sees the development of industry, technology, and the division of labor as A. generally positive but not progressive. The lives of many people may improve, but the world will generally stay the same. B. generally positive and progressive. The world is improving because of these changes, and it will continue to improve. C. generally negative. The creation of new technologies and the division of labor are harmful to all humans, both the wealthy and the poor. D. generally negative. The creation of the division of labor only benefits the wealthy at the expense of the poor. E. both positive and negative. Smith thinks that technology hurts us, while the division of labor helps society progress and develop. http://www.youtube.com/watch?v=RUwS1uAdUcI What point is Hans Rosling trying to make when he describes the global health pre-test? A. He is trying to show how the average person has no idea of the true state of global health. B. He is trying to illustrate how we tend to carry around outdated notions about the state of global health. C. He is trying to make us see that the less-developed countries are far worse off than we ever thought. D. He is trying to drive home the idea that global health has not improved over time despite foreign aid and improvements in medicine. E. He is trying to warn us about the rapid growth in world population. Rosling shows us that we tend to think about global health in terms of “we and them.” Who are the “we” and who are the “them”? A. “We” refers to academics, students, and scholars; “them” refers to the uneducated. B. “We” refers to the average person; “them” refers to politicians and global leaders. C. “We” refers to the wealthy; “them” refers to the poor. D. “We” refers to the Western world; “them” refers to the Third World. E. “We” refers to students; “them” refers to professors. In the life expectancy and fertility rate demonstration, what do the statistics reveal? A. Over time, developed countries produced small families and long lives, whereas developing countries produced large families and short lives. B. The world today looks much like it did in 1962 despite our attempts to help poorer countries develop. C. All countries in the world, even the poorer ones, are trending toward longer lives and smaller families. D. Developed countries are trending toward smaller families but shorter lives. E. All countries tend to make gains and losses in fertility and lifespan, but in the long run there is no significant change. What point does Rosling make about life expectancy in Vietnam as compared to the United States? To what does he attribute the change? A. He indicates that economic change preceded social change. B. He suggests that markets and free trade resulted in the increase in life expectancy. C. He says that the data indicates that the Vietnam War contributed to the decrease in life expectancy during that time, but that it recovered shortly thereafter. D. He says that social change in Asia preceded economic change, and life expectancy in Vietnam increased despite the war. E. He indicates that Vietnam was equal to the United States in life expectancy before the war. According to Rosling, how are regional statistics about child survival rates and GDP potentially misleading? A. Countries have an incentive to lie about the actual survival rates because they want foreign assistance. B. Statistics for the individual countries in a region are often vastly different. C. Regional statistics give us a strong sense of how we can understand development within one region, but it does not allow us to compare across regions. D. The data available over time and from countries within regions is often poorly collected and incomplete. E. Child survival rates cannot be compared regionally, since each culture has a different sense of how important children are. What is Rosling’s main point about statistical databases? A. The data is available but not readily accessible, so we need to create networks to solve that problem. B. The data that comes from these databases is often flawed and unreliable. C. It doesn’t matter whether we have access to these databases because the data can’t be used in an interesting way. D. Statistics can’t tell us very much, but we should do our best to make use of the information we do have. E. The information that could be true is too hard to sort out from what isn’t true because we don’t know how strong the data really is. http://www.marxists.org/archive/lenin/works/1916/imp-hsc/ch10.htm#v22zz99h-298-GUESS Click the link at left to read Chapter 10 of Imperialism, The Highest Stage of Capitalism, then answer the questions below. According to Lenin, what is the fundamental source of a monopoly? A. It is a natural effect of human behavior. B. It is the result of governments and police systems. C. Its source is rooted in democracy. D. It comes from the concentration of production at a high stage. E. It is what follows a socialist system. What are the principal types or manifestations of monopoly capitalism? A. Monopolistic capitalist associations like cartels, syndicates and trusts; and monopolies as a result of colonial policy. B. Monopolization of raw materials and monopolization of finance capital. C. Monopolization of governing structures and monopolies of oligarchies. D. Monopolist capitalist associations like cartels, syndicates and trusts; and monopolies as a result of colonial policy AND monopolization of raw materials and monopolization of finance capital. E. Monopolization of raw materials and monopolization of finance capital AND monopolization of governing structures and monopolies of oligarchies. What is the definition of a rentier state according to Lenin? A. A state that colonizes other states. B. A state whose bourgeoisie live off the export of capital. C. A poor state. D. A wealthy state. E. A colonized state. Overall Lenin’s analysis of the state of capitalism is concerned with: A. The interactions between states. B. The interactions within states. C. The ownership of industry and organizations. D. The interactions within states AND the ownership of industry and organizations. E. All of these options. http://view.vzaar.com/1194665/flashplayer Watch the video at left, and then answer the questions below. The Marshall Plan was developed by the United States after World War II. What was its purpose? A. to feed the hungry of Europe B. to stem the spread of communism C. to maintain an American military presence in Europe D. to feed the hungry of Europe AND to stem the spread of communism E. to stem the spread of communism AND to maintain an American military presence in Europe What kind of aid was sent at first? A. foods, fertilizers, and machines for agriculture B. books, paper, and radios for education C. clothing, medical supplies, and construction equipment D. mostly cash in the form of loans and grants E. people with business expertise to help develop the economy What kind of aid did the United States send to Greece to help its farmers? A. tractors B. mules C. seeds D. fertilizer E. all of these options What was one way that the United States influenced public opinion in Italy during the elections described in the video? A. The United States provided significant food aid to Italy so that the Italians would be inclined to vote against the Communists. B. The Italians had been impressed by the strength and loyalty of the American soldiers, and were inclined to listen to them during the elections. C. There was a large number of young Italians who followed American fashion and culture. D. Italian immigrants in the United States wrote letters to their families in Italy urging them not to vote for Communists. E. The Greeks showed the Italians how much the Americans had helped them, warning that supporting a Communist candidate would mean sacrificing American aid. How did Pope Pius XII undermine the strength of the Communist Party in Italy? A. He encouraged Italians to go out and vote. B. He warned that the Communist Party would legalize abortion. C. He excommunicated many members of the Communist Party. D. He made a speech in support of capitalism. E. He declared that Communists should not be baptized. http://www.youtube.com/watch?v=KVhWqwnZ1eM Use the video at left to answer the questions below. Hans Rosling shares how his students discuss “we” versus “them.” To whom are his students referring? A. the United States and Mexico B. Christians and Muslims C. Democrats and Republicans D. Europe and Asia E. none of these options According to Rosling, what factors contribute to a better quality of life for people in developing countries? A. family planning B. soap and water C. investment D. vaccinations E. all of these options Using his data, Rosling demonstrates a great shift in Mexico. What change does his data demonstrate? A. a decrease in drug usage B. a decrease in the number of jobs available C. an increase in average life expenctancy D. an increase in the rate of violent crime E. all of these options Instead of “developing” and “developed,” Rosling divides countries into four categories. Which of the following is NOT one of them? A. high-income countries B. middle-income countries C. low-income countries D. no-income countries E. collapsing countries Rosling discusses the increased life expectancy in both China and the United States. How are the situations different? A. The U.S. and China are on different continents. B. The life expectancy in China rose much higher than it did in the U.S. C. China first expanded its life expectancy and then grew economically, whereas the U.S. did the reverse. D. Average income and life expectancy steadily increased in the U.S., but they steadily decreased in China. E. all of these options Rosling shows a chart that demonstrates the regional income distribution of the world from 1970 to 2015. During that time, what has happened in South and East Asia? A. Money has flowed out of Asia to developing countries in Africa. B. The average income of citizens of South and East Asia has increased over the last 30 years. C. The average income of citizens of South and East Asia has decreased over the last 30 years. D. The average income of citizens of South and East Asia has surpassed that of Europe and North America. E. There has been no change. Click here to access GapMinder, the data visualizer that Hans Rosling uses. In 2010, which of the following countries had both a higher per-capita GDP and a higher life expectancy than the United States? A. France B. Japan C. Denmark D. Singapore E. Kuwait http://www.garretthardinsociety.org/articles/art_tragedy_of_the_commons.html http://www.youtube.com/watch?v=8a4S23uXIcM The Tragedy of the Commons What is the rough definition of the “commons” given in the article? A. any private property on which others trespass B. behavior that everyone considers to be normal C. a cow that lives in a herd D. government-administered benefits, like unemployment or Social Security E. a shared resource What does Hardin mean by describing pollution as a reverse tragedy of the commons? A. Rather than causing a problem, it resolves a problem. B. Pollution costs us money rather than making us money. C. We are putting something into the commons rather than removing something from it. D. It starts at the other end of the biological pyramid. E. Humans see less of it as time goes on. Hardin says “the air and waters surrounding us cannot readily be fenced, and so the tragedy of the commons as a cesspool must be prevented by different means.” What are those means? A. establishing more international treaties to protect the environment B. using laws or taxes to make the polluter pay for pollution C. punishing consumers for generating waste D. raising awareness about environmental issues E. developing greener products Pacific Garbage Dump According to the news report, what percent of the Gyre is made of plastic? A. 50 percent B. 60 percent C. 70 percent D. 80 percent E. 90 percent Where does the majority of the plastic in the Gyre come from? A. barges that dump trash in the ocean B. storm drains from land C. people throwing litter off boats into the ocean D. remnants from movie sets filmed at sea E. fishing boats processing their catch What does Charles Moore mean by the “throwaway concept”? A. the habitual use of disposable plastic packaging B. the mistaken view that marine ecosystems are infinitely renewable C. a general lack of interest in recycling D. the willingness to discard effective but small-scale environmental policies in deference to broader E. people throwing away their lives in pursuit of money In what way does the Great Pacific Gyre represent issues like global warming a tragedy of the commons? A. because all the plastic trash in it comes from the United States B. because it kills the albatross and makes it impossible for them to reproduce C. surbecause the countries rounding the Pacific Ocean are polluting the water in a way that affects the quality of the resource for all, but no one is specifically accountable for it D. because it causes marine life to compete for increasingly scarce nutrients in the ocean E. because nations in the region all collectively agreed to dump their trash in the Pacific http://www.npr.org/news/specials/climate/video/ http://ngm.nationalgeographic.com/climateconnections/climate-map http://www.npr.org/news/specials/climate/video/wildchronicles.html Use the links provided at left to answer the questions below. Global Warming: It’s All About Carbon How does carbon give us fuel? A. When you burn things that contain carbon the bonds break, giving off energy. B. Burning things creates carbon out of other elements as a result of combustion. C. Carbon is created after oxygen and hydrogen get released. D. Carbon bonds are created thereby giving off energy. E. Carbon is made into fuel by refining oil. National Geographic Climate Map What geographic areas have seen the most significant changes in temperature? A. The African continent. B. The Pacific Ocean. C. The Atlantic Ocean. D. The Arctic Ocean. E. The Indian Ocean. Why does it matter that rain fall steadily rather than in downpours? A. For those countries accustomed to steady rain fall, downpours are actually more efficient ways to catch water. B. Downpours in regions accustomed to steady fall makes them more prone to flooding and damage. C. In general, as long as regions get either steady fall or downpours most things will stay the same. D. Downpours are always more beneficial to crop growth than steady rain. E. Steady rain is always more beneficial to crop growth than downpours. Climate Change Threatens Kona Coffee What is unique about the climate in Hawaii, making it a good place to grow coffee? A. The elevation is high, the nights are cool and the days are humid. B. The elevation is low, the nights are warm and the days are dry. C. The elevation is high, the nights are warm and the days are dry. D. The elevation is low, the nights are cool and the days are dry. E. The elevation is high, the nights are warm and the days are humid. What specific temperature pattern have experts noted about the region where Kona coffee is grown in Hawaii? A. There has been no significant change but the bean production has dropped. B. The nights have warmed up, even though the days have cooled. C. There has been an increase in bean production with the change in climate. D. The nights have cooled even more so than before. E. There has been universally hot days all the way around.

http://www.econlib.org/library/Smith/smWN1.html#B.I,%20Ch.1,%20Of%20the%20Division%20of%20Labor What does Smith mean by division of labor, and how does it affect production? A. He means that each person does their own work to benefit themselves by creating goods. This creates well-crafted goods. B. He argues that in order to become more efficient, we need to put everyone in the same workhouses and eliminate division. C. He says that the division of labor provides farmers with the opportunity to become involved in manufacturing. D. He means that each person makes one small part of a good very quickly, but this is bad for the quality of production overall. E. He means that by having each individual specialize in one thing, they can work together to create products more efficiently and effectively. Which of the following is NOT an example of the circumstances by which the division of labor improves efficiency? A. A doll-making company stops allowing each employee to make one whole doll each and instead appoints each employee to create one part of the doll. B. A family of rug makers buys a loom to speed up their production. C. A mechanic opens a new shop to be nearer to the market. D. A factory changes the responsibilities of its employees so that one group handles heavy boxes and the other group does precision sewing. E. A baker who used to make a dozen cookies at a time buys a giant mixer and oven that enable him to make 20 dozen cookies at a time. Considering the global system of states, what do you think the allegory of the pins has to offer? A. It suggests that there could be a natural harmony of interests among states because they can divide labor among themselves to the benefit of everyone. B. It suggests that states can never be secure enough to cooperate because every state is equally capable of producing the same things. C. It suggests that a central authority is necessary to help states cooperate, in the same way that a manager oversees operations at a factory. D. The allegory of the pins is a great way to think about how wars come about, because states won’t cooperate with each other like pin-makers do. E. The allegory of the pins shows us that there is no natural harmony of interests between states. Smith sees the development of industry, technology, and the division of labor as A. generally positive but not progressive. The lives of many people may improve, but the world will generally stay the same. B. generally positive and progressive. The world is improving because of these changes, and it will continue to improve. C. generally negative. The creation of new technologies and the division of labor are harmful to all humans, both the wealthy and the poor. D. generally negative. The creation of the division of labor only benefits the wealthy at the expense of the poor. E. both positive and negative. Smith thinks that technology hurts us, while the division of labor helps society progress and develop. http://www.youtube.com/watch?v=RUwS1uAdUcI What point is Hans Rosling trying to make when he describes the global health pre-test? A. He is trying to show how the average person has no idea of the true state of global health. B. He is trying to illustrate how we tend to carry around outdated notions about the state of global health. C. He is trying to make us see that the less-developed countries are far worse off than we ever thought. D. He is trying to drive home the idea that global health has not improved over time despite foreign aid and improvements in medicine. E. He is trying to warn us about the rapid growth in world population. Rosling shows us that we tend to think about global health in terms of “we and them.” Who are the “we” and who are the “them”? A. “We” refers to academics, students, and scholars; “them” refers to the uneducated. B. “We” refers to the average person; “them” refers to politicians and global leaders. C. “We” refers to the wealthy; “them” refers to the poor. D. “We” refers to the Western world; “them” refers to the Third World. E. “We” refers to students; “them” refers to professors. In the life expectancy and fertility rate demonstration, what do the statistics reveal? A. Over time, developed countries produced small families and long lives, whereas developing countries produced large families and short lives. B. The world today looks much like it did in 1962 despite our attempts to help poorer countries develop. C. All countries in the world, even the poorer ones, are trending toward longer lives and smaller families. D. Developed countries are trending toward smaller families but shorter lives. E. All countries tend to make gains and losses in fertility and lifespan, but in the long run there is no significant change. What point does Rosling make about life expectancy in Vietnam as compared to the United States? To what does he attribute the change? A. He indicates that economic change preceded social change. B. He suggests that markets and free trade resulted in the increase in life expectancy. C. He says that the data indicates that the Vietnam War contributed to the decrease in life expectancy during that time, but that it recovered shortly thereafter. D. He says that social change in Asia preceded economic change, and life expectancy in Vietnam increased despite the war. E. He indicates that Vietnam was equal to the United States in life expectancy before the war. According to Rosling, how are regional statistics about child survival rates and GDP potentially misleading? A. Countries have an incentive to lie about the actual survival rates because they want foreign assistance. B. Statistics for the individual countries in a region are often vastly different. C. Regional statistics give us a strong sense of how we can understand development within one region, but it does not allow us to compare across regions. D. The data available over time and from countries within regions is often poorly collected and incomplete. E. Child survival rates cannot be compared regionally, since each culture has a different sense of how important children are. What is Rosling’s main point about statistical databases? A. The data is available but not readily accessible, so we need to create networks to solve that problem. B. The data that comes from these databases is often flawed and unreliable. C. It doesn’t matter whether we have access to these databases because the data can’t be used in an interesting way. D. Statistics can’t tell us very much, but we should do our best to make use of the information we do have. E. The information that could be true is too hard to sort out from what isn’t true because we don’t know how strong the data really is. http://www.marxists.org/archive/lenin/works/1916/imp-hsc/ch10.htm#v22zz99h-298-GUESS Click the link at left to read Chapter 10 of Imperialism, The Highest Stage of Capitalism, then answer the questions below. According to Lenin, what is the fundamental source of a monopoly? A. It is a natural effect of human behavior. B. It is the result of governments and police systems. C. Its source is rooted in democracy. D. It comes from the concentration of production at a high stage. E. It is what follows a socialist system. What are the principal types or manifestations of monopoly capitalism? A. Monopolistic capitalist associations like cartels, syndicates and trusts; and monopolies as a result of colonial policy. B. Monopolization of raw materials and monopolization of finance capital. C. Monopolization of governing structures and monopolies of oligarchies. D. Monopolist capitalist associations like cartels, syndicates and trusts; and monopolies as a result of colonial policy AND monopolization of raw materials and monopolization of finance capital. E. Monopolization of raw materials and monopolization of finance capital AND monopolization of governing structures and monopolies of oligarchies. What is the definition of a rentier state according to Lenin? A. A state that colonizes other states. B. A state whose bourgeoisie live off the export of capital. C. A poor state. D. A wealthy state. E. A colonized state. Overall Lenin’s analysis of the state of capitalism is concerned with: A. The interactions between states. B. The interactions within states. C. The ownership of industry and organizations. D. The interactions within states AND the ownership of industry and organizations. E. All of these options. http://view.vzaar.com/1194665/flashplayer Watch the video at left, and then answer the questions below. The Marshall Plan was developed by the United States after World War II. What was its purpose? A. to feed the hungry of Europe B. to stem the spread of communism C. to maintain an American military presence in Europe D. to feed the hungry of Europe AND to stem the spread of communism E. to stem the spread of communism AND to maintain an American military presence in Europe What kind of aid was sent at first? A. foods, fertilizers, and machines for agriculture B. books, paper, and radios for education C. clothing, medical supplies, and construction equipment D. mostly cash in the form of loans and grants E. people with business expertise to help develop the economy What kind of aid did the United States send to Greece to help its farmers? A. tractors B. mules C. seeds D. fertilizer E. all of these options What was one way that the United States influenced public opinion in Italy during the elections described in the video? A. The United States provided significant food aid to Italy so that the Italians would be inclined to vote against the Communists. B. The Italians had been impressed by the strength and loyalty of the American soldiers, and were inclined to listen to them during the elections. C. There was a large number of young Italians who followed American fashion and culture. D. Italian immigrants in the United States wrote letters to their families in Italy urging them not to vote for Communists. E. The Greeks showed the Italians how much the Americans had helped them, warning that supporting a Communist candidate would mean sacrificing American aid. How did Pope Pius XII undermine the strength of the Communist Party in Italy? A. He encouraged Italians to go out and vote. B. He warned that the Communist Party would legalize abortion. C. He excommunicated many members of the Communist Party. D. He made a speech in support of capitalism. E. He declared that Communists should not be baptized. http://www.youtube.com/watch?v=KVhWqwnZ1eM Use the video at left to answer the questions below. Hans Rosling shares how his students discuss “we” versus “them.” To whom are his students referring? A. the United States and Mexico B. Christians and Muslims C. Democrats and Republicans D. Europe and Asia E. none of these options According to Rosling, what factors contribute to a better quality of life for people in developing countries? A. family planning B. soap and water C. investment D. vaccinations E. all of these options Using his data, Rosling demonstrates a great shift in Mexico. What change does his data demonstrate? A. a decrease in drug usage B. a decrease in the number of jobs available C. an increase in average life expenctancy D. an increase in the rate of violent crime E. all of these options Instead of “developing” and “developed,” Rosling divides countries into four categories. Which of the following is NOT one of them? A. high-income countries B. middle-income countries C. low-income countries D. no-income countries E. collapsing countries Rosling discusses the increased life expectancy in both China and the United States. How are the situations different? A. The U.S. and China are on different continents. B. The life expectancy in China rose much higher than it did in the U.S. C. China first expanded its life expectancy and then grew economically, whereas the U.S. did the reverse. D. Average income and life expectancy steadily increased in the U.S., but they steadily decreased in China. E. all of these options Rosling shows a chart that demonstrates the regional income distribution of the world from 1970 to 2015. During that time, what has happened in South and East Asia? A. Money has flowed out of Asia to developing countries in Africa. B. The average income of citizens of South and East Asia has increased over the last 30 years. C. The average income of citizens of South and East Asia has decreased over the last 30 years. D. The average income of citizens of South and East Asia has surpassed that of Europe and North America. E. There has been no change. Click here to access GapMinder, the data visualizer that Hans Rosling uses. In 2010, which of the following countries had both a higher per-capita GDP and a higher life expectancy than the United States? A. France B. Japan C. Denmark D. Singapore E. Kuwait http://www.garretthardinsociety.org/articles/art_tragedy_of_the_commons.html http://www.youtube.com/watch?v=8a4S23uXIcM The Tragedy of the Commons What is the rough definition of the “commons” given in the article? A. any private property on which others trespass B. behavior that everyone considers to be normal C. a cow that lives in a herd D. government-administered benefits, like unemployment or Social Security E. a shared resource What does Hardin mean by describing pollution as a reverse tragedy of the commons? A. Rather than causing a problem, it resolves a problem. B. Pollution costs us money rather than making us money. C. We are putting something into the commons rather than removing something from it. D. It starts at the other end of the biological pyramid. E. Humans see less of it as time goes on. Hardin says “the air and waters surrounding us cannot readily be fenced, and so the tragedy of the commons as a cesspool must be prevented by different means.” What are those means? A. establishing more international treaties to protect the environment B. using laws or taxes to make the polluter pay for pollution C. punishing consumers for generating waste D. raising awareness about environmental issues E. developing greener products Pacific Garbage Dump According to the news report, what percent of the Gyre is made of plastic? A. 50 percent B. 60 percent C. 70 percent D. 80 percent E. 90 percent Where does the majority of the plastic in the Gyre come from? A. barges that dump trash in the ocean B. storm drains from land C. people throwing litter off boats into the ocean D. remnants from movie sets filmed at sea E. fishing boats processing their catch What does Charles Moore mean by the “throwaway concept”? A. the habitual use of disposable plastic packaging B. the mistaken view that marine ecosystems are infinitely renewable C. a general lack of interest in recycling D. the willingness to discard effective but small-scale environmental policies in deference to broader E. people throwing away their lives in pursuit of money In what way does the Great Pacific Gyre represent issues like global warming a tragedy of the commons? A. because all the plastic trash in it comes from the United States B. because it kills the albatross and makes it impossible for them to reproduce C. surbecause the countries rounding the Pacific Ocean are polluting the water in a way that affects the quality of the resource for all, but no one is specifically accountable for it D. because it causes marine life to compete for increasingly scarce nutrients in the ocean E. because nations in the region all collectively agreed to dump their trash in the Pacific http://www.npr.org/news/specials/climate/video/ http://ngm.nationalgeographic.com/climateconnections/climate-map http://www.npr.org/news/specials/climate/video/wildchronicles.html Use the links provided at left to answer the questions below. Global Warming: It’s All About Carbon How does carbon give us fuel? A. When you burn things that contain carbon the bonds break, giving off energy. B. Burning things creates carbon out of other elements as a result of combustion. C. Carbon is created after oxygen and hydrogen get released. D. Carbon bonds are created thereby giving off energy. E. Carbon is made into fuel by refining oil. National Geographic Climate Map What geographic areas have seen the most significant changes in temperature? A. The African continent. B. The Pacific Ocean. C. The Atlantic Ocean. D. The Arctic Ocean. E. The Indian Ocean. Why does it matter that rain fall steadily rather than in downpours? A. For those countries accustomed to steady rain fall, downpours are actually more efficient ways to catch water. B. Downpours in regions accustomed to steady fall makes them more prone to flooding and damage. C. In general, as long as regions get either steady fall or downpours most things will stay the same. D. Downpours are always more beneficial to crop growth than steady rain. E. Steady rain is always more beneficial to crop growth than downpours. Climate Change Threatens Kona Coffee What is unique about the climate in Hawaii, making it a good place to grow coffee? A. The elevation is high, the nights are cool and the days are humid. B. The elevation is low, the nights are warm and the days are dry. C. The elevation is high, the nights are warm and the days are dry. D. The elevation is low, the nights are cool and the days are dry. E. The elevation is high, the nights are warm and the days are humid. What specific temperature pattern have experts noted about the region where Kona coffee is grown in Hawaii? A. There has been no significant change but the bean production has dropped. B. The nights have warmed up, even though the days have cooled. C. There has been an increase in bean production with the change in climate. D. The nights have cooled even more so than before. E. There has been universally hot days all the way around.

http://www.econlib.org/library/Smith/smWN1.html#B.I,%20Ch.1,%20Of%20the%20Division%20of%20Labor What does Smith mean by division of labor, and … Read More...
Chapter 15 Practice Problems (Practice – no credit) Due: 11:59pm on Friday, May 16, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Fluid Pressure in a U-Tube A U-tube is filled with water, and the two arms are capped. The tube is cylindrical, and the right arm has twice the radius of the left arm. The caps have negligible mass, are watertight, and can freely slide up and down the tube. Part A A one-inch depth of sand is poured onto the cap on each arm. After the caps have moved (if necessary) to reestablish equilibrium, is the right cap higher, lower, or the same height as the left cap? You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Pressure in the Ocean The pressure at 10 below the surface of the ocean is about 2.00×105 . Part A higher lower the same height m Pa Which of the following statements is true? You did not open hints for this part. ANSWER: Part B Now consider the pressure 20 below the surface of the ocean. Which of the following statements is true? You did not open hints for this part. ANSWER: Relating Pressure and Height in a Container Learning Goal: To understand the derivation of the law relating height and pressure in a container. The weight of a column of seawater 1 in cross section and 10 high is about 2.00×105 . The weight of a column of seawater 1 in cross section and 10 high plus the weight of a column of air with the same cross section extending up to the top of the atmosphere is about 2.00×105 . The weight of 1 of seawater at 10 below the surface of the ocean is about 2.00×105 . The density of seawater is about 2.00×105 times the density of air at sea level. m2 m N m2 m N m3 m N m The pressure is twice that at a depth of 10 . The pressure is the same as that at a depth of 10 . The pressure is equal to that at a depth of 10 plus the weight per 1 cross sectional area of a column of seawater 10 high. The pressure is equal to the weight per 1 cross sectional area of a column of seawater 20 high. m m m m2 m m2 m In this problem, you will derive the law relating pressure to height in a container by analyzing a particular system. A container of uniform cross-sectional area is filled with liquid of uniform density . Consider a thin horizontal layer of liquid (thickness ) at a height as measured from the bottom of the container. Let the pressure exerted upward on the bottom of the layer be and the pressure exerted downward on the top be . Assume throughout the problem that the system is in equilibrium (the container has not been recently shaken or moved, etc.). Part A What is , the magnitude of the force exerted upward on the bottom of the liquid? You did not open hints for this part. ANSWER: Part B What is , the magnitude of the force exerted downward on the top of the liquid? A  dy y p p + dp Fup Fup = Fdown You did not open hints for this part. ANSWER: Part C What is the weight of the thin layer of liquid? Express your answer in terms of quantities given in the problem introduction and , the magnitude of the acceleration due to gravity. You did not open hints for this part. ANSWER: Part D Since the liquid is in equilibrium, the net force on the thin layer of liquid is zero. Complete the force equation for the sum of the vertical forces acting on the liquid layer described in the problem introduction. Express your answer in terms of quantities given in the problem introduction and taking upward forces to be positive. You did not open hints for this part. ANSWER: Fdown = wlayer g wlayer = Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). A Submerged Ball A ball of mass and volume is lowered on a string into a fluid of density . Assume that the object would sink to the bottom if it were not supported by the string. Part A  = = i Fy,i mb V f What is the tension in the string when the ball is fully submerged but not touching the bottom, as shown in the figure? Express your answer in terms of any or all of the given quantities and , the magnitude of the acceleration due to gravity. You did not open hints for this part. ANSWER: Archimedes’ Principle Learning Goal: To understand the applications of Archimedes’ principle. Archimedes’ principle is a powerful tool for solving many problems involving equilibrium in fluids. It states the following: When a body is partially or completely submerged in a fluid (either a liquid or a gas), the fluid exerts an upward force on the body equal to the weight of the fluid displaced by the body. As a result of the upward Archimedes force (often called the buoyant force), some objects may float in a fluid, and all of them appear to weigh less. This is the familiar phenomenon of buoyancy. Quantitatively, the buoyant force can be found as , where is the force, is the density of the fluid, is the magnitude of the acceleration due to gravity, and is the volume of the displaced fluid. In this problem, you will be asked several qualitative questions that should help you develop a feel for Archimedes’ principle. An object is placed in a fluid and then released. Assume that the object either floats to the surface (settling so that the object is partly above and partly below the fluid surface) or sinks to the bottom. (Note that for Parts A through D, you should assume that the object has settled in equilibrium.) Part A Consider the following statement: The magnitude of the buoyant force is equal to the weight of fluid displaced by the object. Under what circumstances is this statement true? T g T = Fbuoyant = fluidgV Fbuoyant fluid g V You did not open hints for this part. ANSWER: Part B Consider the following statement: The magnitude of the buoyant force is equal to the weight of the amount of fluid that has the same total volume as the object. Under what circumstances is this statement true? You did not open hints for this part. ANSWER: Part C Consider the following statement: The magnitude of the buoyant force equals the weight of the object. Under what circumstances is this statement true? for every object submerged partially or completely in a fluid only for an object that floats only for an object that sinks for no object submerged in a fluid for an object that is partially submerged in a fluid only for an object that floats for an object completely submerged in a fluid for no object partially or completely submerged in a fluid You did not open hints for this part. ANSWER: Part D Consider the following statement: The magnitude of the buoyant force is less than the weight of the object. Under what circumstances is this statement true? ANSWER: Now apply what you know to some more complicated situations. Part E An object is floating in equilibrium on the surface of a liquid. The object is then removed and placed in another container, filled with a denser liquid. What would you observe? You did not open hints for this part. ANSWER: for every object submerged partially or completely in a fluid for an object that floats only for an object that sinks for no object submerged in a fluid for every object submerged partially or completely in a fluid for an object that floats for an object that sinks for no object submerged in a fluid Part F An object is floating in equilibrium on the surface of a liquid. The object is then removed and placed in another container, filled with a less dense liquid. What would you observe? You did not open hints for this part. ANSWER: Part G Two objects, T and B, have identical size and shape and have uniform density. They are carefully placed in a container filled with a liquid. Both objects float in equilibrium. Less of object T is submerged than of object B, which floats, fully submerged, closer to the bottom of the container. Which of the following statements is true? ANSWER: The object would sink all the way to the bottom. The object would float submerged more deeply than in the first container. The object would float submerged less deeply than in the first container. More than one of these outcomes is possible. The object would sink all the way to the bottom. The object would float submerged more deeply than in the first container. The object would float submerged less deeply than in the first container. More than one of these outcomes is possible. Object T has a greater density than object B. Object B has a greater density than object T. Both objects have the same density. ± Buoyant Force Conceptual Question A rectangular wooden block of weight floats with exactly one-half of its volume below the waterline. Part A What is the buoyant force acting on the block? You did not open hints for this part. ANSWER: Part B W The buoyant force cannot be determined. 2W W 1 W 2 The density of water is 1.00 . What is the density of the block? You did not open hints for this part. ANSWER: Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). g/cm3 2.00 between 1.00 and 2.00 1.00 between 0.50 and 1.00 0.50 The density cannot be determined. g/cm3 g/cm3 g/cm3 g/cm3 g/cm3 Flow Velocity of Blood Conceptual Question Arteriosclerotic plaques forming on the inner walls of arteries can decrease the effective cross-sectional area of an artery. Even small changes in the effective area of an artery can lead to very large changes in the blood pressure in the artery and possibly to the collapse of the blood vessel. Imagine a healthy artery, with blood flow velocity of and mass per unit volume of . The kinetic energy per unit volume of blood is given by Imagine that plaque has narrowed an artery to one-fifth of its normal cross-sectional area (an 80% blockage). Part A Compared to normal blood flow velocity, , what is the velocity of blood as it passes through this blockage? You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Part C v0 = 0.14 m/s  = 1050 kg/m3 K0 =  . 1 2 v20 v0 80v0 20v0 5v0 v0/5 This question will be shown after you complete previous question(s). For parts D – F imagine that plaque has grown to a 90% blockage. Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). ± Playing with a Water Hose Two children, Ferdinand and Isabella, are playing with a water hose on a sunny summer day. Isabella is holding the hose in her hand 1.0 meters above the ground and is trying to spray Ferdinand, who is standing 10.0 meters away. Part A Will Isabella be able to spray Ferdinand if the water is flowing out of the hose at a constant speed of 3.5 meters per second? Assume that the hose is pointed parallel to the ground and take the magnitude of the acceleration due to gravity to be 9.81 meters per second, per second. You did not open hints for this part. v0 g ANSWER: Part B This question will be shown after you complete previous question(s). Tactics Box 15.2 Finding Whether an Object Floats or Sinks Learning Goal: To practice Tactics Box 15.2 Finding whether an object floats or sinks. If you hold an object underwater and then release it, it can float to the surface, sink, or remain “hanging” in the water, depending on whether the fluid density is larger than, smaller than, or equal to the object’s average density . These conditions are summarized in this Tactics Box. Yes No f avg TACTICS BOX 15.2 Finding whether an object floats or sinks Object sinks Object floats Object has neutral buoyancy An object sinks if it weighs more than the fluid it displaces, that is, if its average density is greater than the density of the fluid: . An object floats on the surface if it weighs less than the fluid it displaces, that is, if its average density is less than the density of the fluid: . An object hangs motionless in the fluid if it weighs exactly the same as the fluid it displaces. It has neutral buoyancy if its average density equals the density of the fluid: . Part A Ice at 0.0 has a density of 917 . A 3.00 ice cube is gently released inside a small container filled with oil and is observed to be neutrally buoyant. What is the density of the oil, ? Express your answer in kilograms per meter cubed to three significant figures. ANSWER: Part B Once the ice cube melts, what happens to the liquid water that it produces? You did not open hints for this part. ANSWER: avg > f avg < f avg = f 'C kg/m3 cm3 oil oil = kg/m3 Part C What happens if some ethyl alcohol of density 790 is poured into the container after the ice cube has melted? ANSWER: Score Summary: Your score on this assignment is 0%. You received 0 out of a possible total of 0 points. The liquid water sinks to the bottom of the container. The liquid water rises to the surface and floats on top of the oil. The liquid water is in static equilibrium at the location where the ice cube was originally placed. kg/m3 A layer of ethyl alcohol forms between the oil and the water. The layer of ethyl alcohol forms at the bottom of the container. The layer of ethyl alcohol forms on the surface.

Chapter 15 Practice Problems (Practice – no credit) Due: 11:59pm on Friday, May 16, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Fluid Pressure in a U-Tube A U-tube is filled with water, and the two arms are capped. The tube is cylindrical, and the right arm has twice the radius of the left arm. The caps have negligible mass, are watertight, and can freely slide up and down the tube. Part A A one-inch depth of sand is poured onto the cap on each arm. After the caps have moved (if necessary) to reestablish equilibrium, is the right cap higher, lower, or the same height as the left cap? You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Pressure in the Ocean The pressure at 10 below the surface of the ocean is about 2.00×105 . Part A higher lower the same height m Pa Which of the following statements is true? You did not open hints for this part. ANSWER: Part B Now consider the pressure 20 below the surface of the ocean. Which of the following statements is true? You did not open hints for this part. ANSWER: Relating Pressure and Height in a Container Learning Goal: To understand the derivation of the law relating height and pressure in a container. The weight of a column of seawater 1 in cross section and 10 high is about 2.00×105 . The weight of a column of seawater 1 in cross section and 10 high plus the weight of a column of air with the same cross section extending up to the top of the atmosphere is about 2.00×105 . The weight of 1 of seawater at 10 below the surface of the ocean is about 2.00×105 . The density of seawater is about 2.00×105 times the density of air at sea level. m2 m N m2 m N m3 m N m The pressure is twice that at a depth of 10 . The pressure is the same as that at a depth of 10 . The pressure is equal to that at a depth of 10 plus the weight per 1 cross sectional area of a column of seawater 10 high. The pressure is equal to the weight per 1 cross sectional area of a column of seawater 20 high. m m m m2 m m2 m In this problem, you will derive the law relating pressure to height in a container by analyzing a particular system. A container of uniform cross-sectional area is filled with liquid of uniform density . Consider a thin horizontal layer of liquid (thickness ) at a height as measured from the bottom of the container. Let the pressure exerted upward on the bottom of the layer be and the pressure exerted downward on the top be . Assume throughout the problem that the system is in equilibrium (the container has not been recently shaken or moved, etc.). Part A What is , the magnitude of the force exerted upward on the bottom of the liquid? You did not open hints for this part. ANSWER: Part B What is , the magnitude of the force exerted downward on the top of the liquid? A  dy y p p + dp Fup Fup = Fdown You did not open hints for this part. ANSWER: Part C What is the weight of the thin layer of liquid? Express your answer in terms of quantities given in the problem introduction and , the magnitude of the acceleration due to gravity. You did not open hints for this part. ANSWER: Part D Since the liquid is in equilibrium, the net force on the thin layer of liquid is zero. Complete the force equation for the sum of the vertical forces acting on the liquid layer described in the problem introduction. Express your answer in terms of quantities given in the problem introduction and taking upward forces to be positive. You did not open hints for this part. ANSWER: Fdown = wlayer g wlayer = Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). A Submerged Ball A ball of mass and volume is lowered on a string into a fluid of density . Assume that the object would sink to the bottom if it were not supported by the string. Part A  = = i Fy,i mb V f What is the tension in the string when the ball is fully submerged but not touching the bottom, as shown in the figure? Express your answer in terms of any or all of the given quantities and , the magnitude of the acceleration due to gravity. You did not open hints for this part. ANSWER: Archimedes’ Principle Learning Goal: To understand the applications of Archimedes’ principle. Archimedes’ principle is a powerful tool for solving many problems involving equilibrium in fluids. It states the following: When a body is partially or completely submerged in a fluid (either a liquid or a gas), the fluid exerts an upward force on the body equal to the weight of the fluid displaced by the body. As a result of the upward Archimedes force (often called the buoyant force), some objects may float in a fluid, and all of them appear to weigh less. This is the familiar phenomenon of buoyancy. Quantitatively, the buoyant force can be found as , where is the force, is the density of the fluid, is the magnitude of the acceleration due to gravity, and is the volume of the displaced fluid. In this problem, you will be asked several qualitative questions that should help you develop a feel for Archimedes’ principle. An object is placed in a fluid and then released. Assume that the object either floats to the surface (settling so that the object is partly above and partly below the fluid surface) or sinks to the bottom. (Note that for Parts A through D, you should assume that the object has settled in equilibrium.) Part A Consider the following statement: The magnitude of the buoyant force is equal to the weight of fluid displaced by the object. Under what circumstances is this statement true? T g T = Fbuoyant = fluidgV Fbuoyant fluid g V You did not open hints for this part. ANSWER: Part B Consider the following statement: The magnitude of the buoyant force is equal to the weight of the amount of fluid that has the same total volume as the object. Under what circumstances is this statement true? You did not open hints for this part. ANSWER: Part C Consider the following statement: The magnitude of the buoyant force equals the weight of the object. Under what circumstances is this statement true? for every object submerged partially or completely in a fluid only for an object that floats only for an object that sinks for no object submerged in a fluid for an object that is partially submerged in a fluid only for an object that floats for an object completely submerged in a fluid for no object partially or completely submerged in a fluid You did not open hints for this part. ANSWER: Part D Consider the following statement: The magnitude of the buoyant force is less than the weight of the object. Under what circumstances is this statement true? ANSWER: Now apply what you know to some more complicated situations. Part E An object is floating in equilibrium on the surface of a liquid. The object is then removed and placed in another container, filled with a denser liquid. What would you observe? You did not open hints for this part. ANSWER: for every object submerged partially or completely in a fluid for an object that floats only for an object that sinks for no object submerged in a fluid for every object submerged partially or completely in a fluid for an object that floats for an object that sinks for no object submerged in a fluid Part F An object is floating in equilibrium on the surface of a liquid. The object is then removed and placed in another container, filled with a less dense liquid. What would you observe? You did not open hints for this part. ANSWER: Part G Two objects, T and B, have identical size and shape and have uniform density. They are carefully placed in a container filled with a liquid. Both objects float in equilibrium. Less of object T is submerged than of object B, which floats, fully submerged, closer to the bottom of the container. Which of the following statements is true? ANSWER: The object would sink all the way to the bottom. The object would float submerged more deeply than in the first container. The object would float submerged less deeply than in the first container. More than one of these outcomes is possible. The object would sink all the way to the bottom. The object would float submerged more deeply than in the first container. The object would float submerged less deeply than in the first container. More than one of these outcomes is possible. Object T has a greater density than object B. Object B has a greater density than object T. Both objects have the same density. ± Buoyant Force Conceptual Question A rectangular wooden block of weight floats with exactly one-half of its volume below the waterline. Part A What is the buoyant force acting on the block? You did not open hints for this part. ANSWER: Part B W The buoyant force cannot be determined. 2W W 1 W 2 The density of water is 1.00 . What is the density of the block? You did not open hints for this part. ANSWER: Part C This question will be shown after you complete previous question(s). Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). g/cm3 2.00 between 1.00 and 2.00 1.00 between 0.50 and 1.00 0.50 The density cannot be determined. g/cm3 g/cm3 g/cm3 g/cm3 g/cm3 Flow Velocity of Blood Conceptual Question Arteriosclerotic plaques forming on the inner walls of arteries can decrease the effective cross-sectional area of an artery. Even small changes in the effective area of an artery can lead to very large changes in the blood pressure in the artery and possibly to the collapse of the blood vessel. Imagine a healthy artery, with blood flow velocity of and mass per unit volume of . The kinetic energy per unit volume of blood is given by Imagine that plaque has narrowed an artery to one-fifth of its normal cross-sectional area (an 80% blockage). Part A Compared to normal blood flow velocity, , what is the velocity of blood as it passes through this blockage? You did not open hints for this part. ANSWER: Part B This question will be shown after you complete previous question(s). Part C v0 = 0.14 m/s  = 1050 kg/m3 K0 =  . 1 2 v20 v0 80v0 20v0 5v0 v0/5 This question will be shown after you complete previous question(s). For parts D – F imagine that plaque has grown to a 90% blockage. Part D This question will be shown after you complete previous question(s). Part E This question will be shown after you complete previous question(s). Part F This question will be shown after you complete previous question(s). ± Playing with a Water Hose Two children, Ferdinand and Isabella, are playing with a water hose on a sunny summer day. Isabella is holding the hose in her hand 1.0 meters above the ground and is trying to spray Ferdinand, who is standing 10.0 meters away. Part A Will Isabella be able to spray Ferdinand if the water is flowing out of the hose at a constant speed of 3.5 meters per second? Assume that the hose is pointed parallel to the ground and take the magnitude of the acceleration due to gravity to be 9.81 meters per second, per second. You did not open hints for this part. v0 g ANSWER: Part B This question will be shown after you complete previous question(s). Tactics Box 15.2 Finding Whether an Object Floats or Sinks Learning Goal: To practice Tactics Box 15.2 Finding whether an object floats or sinks. If you hold an object underwater and then release it, it can float to the surface, sink, or remain “hanging” in the water, depending on whether the fluid density is larger than, smaller than, or equal to the object’s average density . These conditions are summarized in this Tactics Box. Yes No f avg TACTICS BOX 15.2 Finding whether an object floats or sinks Object sinks Object floats Object has neutral buoyancy An object sinks if it weighs more than the fluid it displaces, that is, if its average density is greater than the density of the fluid: . An object floats on the surface if it weighs less than the fluid it displaces, that is, if its average density is less than the density of the fluid: . An object hangs motionless in the fluid if it weighs exactly the same as the fluid it displaces. It has neutral buoyancy if its average density equals the density of the fluid: . Part A Ice at 0.0 has a density of 917 . A 3.00 ice cube is gently released inside a small container filled with oil and is observed to be neutrally buoyant. What is the density of the oil, ? Express your answer in kilograms per meter cubed to three significant figures. ANSWER: Part B Once the ice cube melts, what happens to the liquid water that it produces? You did not open hints for this part. ANSWER: avg > f avg < f avg = f 'C kg/m3 cm3 oil oil = kg/m3 Part C What happens if some ethyl alcohol of density 790 is poured into the container after the ice cube has melted? ANSWER: Score Summary: Your score on this assignment is 0%. You received 0 out of a possible total of 0 points. The liquid water sinks to the bottom of the container. The liquid water rises to the surface and floats on top of the oil. The liquid water is in static equilibrium at the location where the ice cube was originally placed. kg/m3 A layer of ethyl alcohol forms between the oil and the water. The layer of ethyl alcohol forms at the bottom of the container. The layer of ethyl alcohol forms on the surface.

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Learning Objectives This part begins with what are probably the basic questions for a designer of a computing sytem’s human interface: • How should the functionality of the system be described and presented to the user? • How can the design of the interface help the user to understand and successfully use the system? Learning Goals At the conclusion of this module you will be able to: • define the user’s movement among the displays that make up the system; • the addition of visual and spatial cues to the information organization; and • methods of structuring and presenting the interface. Introduction This module deals with the development and utilization of a system. We all have systems for doing things. For instance, we may have a system for handling routine situations around the house that makes sense only to us. Or, we may be oriented toward systems that have a more widespread understanding such as personal finance or how to fill out our IRS forms. When humans use a system, whether natural or man-made, they do so based on their understanding of that system. A totally accurate understanding of a system is not a necessary condition for effective use of that system. Key Terms Systems, User Model, Model, Metaphor, Concept Modeling The Development of Human Systems I. The organization of knowledge about a phenomenon or system constitutes the human’s conceptual model of that system. Information gained from experience with a system contributes to the model, and the model in turn provides a reference or guide for future experience with the system. A. (Reinstein and Hersh, 1984) – a set of concepts a person gradually acquires to explain the behavior of a system. …. That enables that person to understand and interact with the system. 1. For the user, the important thing about a model is its ability to predict: when confronted with unfamiliar or incompletely understood situations, the user relies on their model, their conceptual understanding of the system, to make educated guesses about how to proceed. If the user’s model accurately reflects the effects of the system, then he will be more successful in learning and using the system, and likely will perceive the system as easy to use. 2. Because the model can server this important role in design of helping to create an understandable and predictable system, the creation of the user’s conceptual model should be the first task of system development. One of the more important examples of the use of conceptual model, the XEROX Star office automation system (whose design greatly influenced Apple’s Lisa and Macintosh systems), started with thirty man-years of design work on the user interface before either the hardware or the system software was designed (Smith, Irby, Kimball, Verplank and Harselm, 1982). 3. The conceptual model does not have to be an accurate representation of how the system actually functions. Indeed, it can be quite different from reality, and in most if not all circumstances for systems as complex as computers, should be. 4. The model may be a myth or metaphor, that explains the system: it “suggests that the computer is like something with which the user is already familiar” (Rubinstein and Hersh, 1984, p. 43), or provides a simple explanation of the system which can be used to predict the system’s behavior. 5. ….the conceptual models people form are based on their interactions with an environment … “people who have different roles within an environment … will form different conceptual systems of those environments. 6. People whose essential interaction with an environment is to create it will almost inevitably have an understanding and conceptualization of it which is different from those whose major interaction with it is to use it” Action Assignment Based on the readings for this module, please identify a personal “system” with which you act and perform within. This should be from personal experience and one that assists in providing a model for organization, understanding and problem solving.

Learning Objectives This part begins with what are probably the basic questions for a designer of a computing sytem’s human interface: • How should the functionality of the system be described and presented to the user? • How can the design of the interface help the user to understand and successfully use the system? Learning Goals At the conclusion of this module you will be able to: • define the user’s movement among the displays that make up the system; • the addition of visual and spatial cues to the information organization; and • methods of structuring and presenting the interface. Introduction This module deals with the development and utilization of a system. We all have systems for doing things. For instance, we may have a system for handling routine situations around the house that makes sense only to us. Or, we may be oriented toward systems that have a more widespread understanding such as personal finance or how to fill out our IRS forms. When humans use a system, whether natural or man-made, they do so based on their understanding of that system. A totally accurate understanding of a system is not a necessary condition for effective use of that system. Key Terms Systems, User Model, Model, Metaphor, Concept Modeling The Development of Human Systems I. The organization of knowledge about a phenomenon or system constitutes the human’s conceptual model of that system. Information gained from experience with a system contributes to the model, and the model in turn provides a reference or guide for future experience with the system. A. (Reinstein and Hersh, 1984) – a set of concepts a person gradually acquires to explain the behavior of a system. …. That enables that person to understand and interact with the system. 1. For the user, the important thing about a model is its ability to predict: when confronted with unfamiliar or incompletely understood situations, the user relies on their model, their conceptual understanding of the system, to make educated guesses about how to proceed. If the user’s model accurately reflects the effects of the system, then he will be more successful in learning and using the system, and likely will perceive the system as easy to use. 2. Because the model can server this important role in design of helping to create an understandable and predictable system, the creation of the user’s conceptual model should be the first task of system development. One of the more important examples of the use of conceptual model, the XEROX Star office automation system (whose design greatly influenced Apple’s Lisa and Macintosh systems), started with thirty man-years of design work on the user interface before either the hardware or the system software was designed (Smith, Irby, Kimball, Verplank and Harselm, 1982). 3. The conceptual model does not have to be an accurate representation of how the system actually functions. Indeed, it can be quite different from reality, and in most if not all circumstances for systems as complex as computers, should be. 4. The model may be a myth or metaphor, that explains the system: it “suggests that the computer is like something with which the user is already familiar” (Rubinstein and Hersh, 1984, p. 43), or provides a simple explanation of the system which can be used to predict the system’s behavior. 5. ….the conceptual models people form are based on their interactions with an environment … “people who have different roles within an environment … will form different conceptual systems of those environments. 6. People whose essential interaction with an environment is to create it will almost inevitably have an understanding and conceptualization of it which is different from those whose major interaction with it is to use it” Action Assignment Based on the readings for this module, please identify a personal “system” with which you act and perform within. This should be from personal experience and one that assists in providing a model for organization, understanding and problem solving.

Assignment 5 Due: 11:59pm on Wednesday, March 5, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 6.13 A hand presses down on the book in the figure. Part A Is the normal force of the table on the book larger than, smaller than, or equal to ? ANSWER: Correct mg Equal to Larger than Smaller than mg mg mg Problem 6.2 The three ropes in the figure are tied to a small, very light ring. Two of these ropes are anchored to walls at right angles with the tensions shown in the figure. Part A What is the magnitude of the tension in the third rope? Express your answer using two significant figures. ANSWER: Correct Part B What is the direction of the tension in the third rope? Express your answer using two significant figures. T  3 T3 = 94 N T  3 Typesetting math: 100% ANSWER: Correct The Normal Force When an object rests on a surface, there is always a force perpendicular to the surface; we call this the normal force, denoted by . The two questions to the right will explore the normal force. Part A A man attempts to pick up his suitcase of weight by pulling straight up on the handle. However, he is unable to lift the suitcase from the floor. Which statement about the magnitude of the normal force acting on the suitcase is true during the time that the man pulls upward on the suitcase? Hint 1. How to approach this problem First, identify the forces that act on the suitcase and draw a free-body diagram. Then use the fact that the suitcase is in equilibrium, , to examine how the forces acting on the suitcase relate to each other. Hint 2. Identify the correct free-body diagram Which of the figures represents the free-body diagram of the suitcase while the man is pulling on the handle with a force of magnitude ? = 58   below horizontal n ws n F = 0 fpull Typesetting math: 100% ANSWER: ANSWER: Correct Part B A B C D The magnitude of the normal force is equal to the magnitude of the weight of the suitcase. The magnitude of the normal force is equal to the magnitude of the weight of the suitcase minus the magnitude of the force of the pull. The magnitude of the normal force is equal to the sum of the magnitude of the force of the pull and the magnitude of the suitcase’s weight. The magnitude of the normal force is greater than the magnitude of the weight of the suitcase. Typesetting math: 100% Now assume that the man of weight is tired and decides to sit on his suitcase. Which statement about the magnitude of the normal force acting on the suitcase is true during the time that the man is sitting on the suitcase? Hint 1. Identify the correct free-body diagram. Which of the figures represents the free-body diagram while the man is sitting atop the suitcase? Here the vector labeled is a force that has the same magnitude as the man’s weight. ANSWER: wm n wm Typesetting math: 100% ANSWER: Correct Recognize that the normal force acting on an object is not always equal to the weight of that object. This is an important point to understand. Problem 6.5 A construction worker with a weight of 880 stands on a roof that is sloped at 18 . Part A What is the magnitude of the normal force of the roof on the worker? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct A B C D The magnitude of the normal force is equal to the magnitude of the suitcase’s weight. The magnitude of the normal force is equal to the magnitude of the suitcase’s weight minus the magnitude of the man’s weight. The magnitude of the normal force is equal to the sum of the magnitude of the man’s weight and the magnitude of the suitcase’s weight. The magnitude of the normal force is less than the magnitude of the suitcase’s weight. N  n = 840 N Typesetting math: 100% Problem 6.6 In each of the two free-body diagrams, the forces are acting on a 3.0 object. Part A For diagram , find the value of , the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B For diagram the part A, find the value of the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: kg ax x ax = -0.67 m s2 ay, y Typesetting math: 100% Correct Part C For diagram , find the value of , the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part D For diagram the part C, find the value of , the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: ay = 0 m s2 ax x ax = 0.67 m s2 ay y Typesetting math: 100% Correct Problem 6.7 In each of the two free-body diagrams, the forces are acting on a 3.0 object. Part A Find the value of , the component of the acceleration in diagram (a). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct ay = 0 m s2 kg ax x ax = 0.99 m s2 Typesetting math: 100% Part B Find the value of , the component of the acceleration in diagram (a). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C Find the value of , the component of the acceleration in diagram (b). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part D Find the value of , the component of the acceleration in diagram (b). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct ay y ay = 0 m s2 ax x ax = -0.18 m s2 ay y ay = 0 m s2 Typesetting math: 100% Problem 6.10 A horizontal rope is tied to a 53.0 box on frictionless ice. What is the tension in the rope if: Part A The box is at rest? Express your answer as an integer and include the appropriate units. ANSWER: Correct Part B The box moves at a steady = 4.80 ? Express your answer as an integer and include the appropriate units. ANSWER: Correct Part C The box = 4.80 and = 4.60 ? Express your answer to three significant figures and include the appropriate units. ANSWER: kg T = 0 N vx m/s T = 0 N vx m/s ax m/s2 Typesetting math: 100% Correct Problem 6.14 It takes the elevator in a skyscraper 4.5 to reach its cruising speed of 11 . A 60 passenger gets aboard on the ground floor. Part A What is the passenger’s weight before the elevator starts moving? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the passenger’s weight while the elevator is speeding up? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C What is the passenger’s weight after the elevator reaches its cruising speed? T = 244 N s m/s kg w = 590 N w = 730 N Typesetting math: 100% Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Block on an Incline A block lies on a plane raised an angle from the horizontal. Three forces act upon the block: , the force of gravity; , the normal force; and , the force of friction. The coefficient of friction is large enough to prevent the block from sliding . Part A Consider coordinate system a, with the x axis along the plane. Which forces lie along the axes? ANSWER: w = 590 N  F  w F n F  f Typesetting math: 100% Correct Part B Which forces lie along the axes of the coordinate system b, in which the y axis is vertical? ANSWER: Correct only only only and and and and and F  f F  n F  w F  f F  n F  f F  w F  n F w F  f F  n F w only only only and and and and and F  f F  n F  w F  f F  n F  f F  w F  n F w F  f F  n F w Typesetting math: 100% Usually the best advice is to choose coordinate system so that the acceleration of the system is directly along one of the coordinate axes. If the system isn’t accelerating, then you are better off choosing the coordinate system with the most vectors along the coordinate axes. But now you are going to ignore that advice. You will find the normal force, , using vertical coordinate system b. In these coordinates you will find the magnitude appearing in both the x and y equations, each multiplied by a trigonometric function. Part C Because the block is not moving, the sum of the y components of the forces acting on the block must be zero. Find an expression for the sum of the y components of the forces acting on the block, using coordinate system b. Express your answer in terms of some or all of the variables , , , and . Hint 1. Find the y component of Write an expression for , the y component of the force , using coordinate system b. Express your answer in terms of and . Hint 1. Some geometry help – a useful angle The smaller angle between and the y-axis is also , as shown in the figure. ANSWER: F  n Fn Fn Ff Fw  F n Fny F  n Fn  F  n  Typesetting math: 100% Hint 2. Find the y component of Write an expression for , the y component of the force , using coordinate system b. Express your answer in terms of and . Hint 1. Some geometry help – a useful angle The smaller angle between and the x-axis is also , as shown in the figure. ANSWER: ANSWER: Fny = Fncos() F f Ffy F f Ff  F  f  Ffy = Ffsin() Fy = 0 = Fncos() + Ffsin() − Fw Typesetting math: 100% Correct Part D Because the block is not moving, the sum of the x components of the forces acting on the block must be zero. Find an expression for the sum of the x components of the forces acting on the block, using coordinate system b. Express your answer in terms of some or all of the variables , , , and . Hint 1. Find the x component of Write an expression for , the x component of the force , using coordinate system b. Express your answer in terms of and . ANSWER: ANSWER: Correct Part E To find the magnitude of the normal force, you must express in terms of since is an unknown. Using the equations you found in the two previous parts, find an expression for involving and but not . Hint 1. How to approach the problem From your answers to the previous two parts you should have two force equations ( and ). Combine these equations to eliminate . The key is to multiply the Fn Ff Fw  F n Fnx F  n Fn  Fnx = −Fnsin() Fx = 0 = −Fnsin() + Ffcos() Fn Fw Ff Fn Fw  Ff Typesetting math: 100% Fy = 0 Fx = 0 Ff equation for the y components by and the equation for the x components by , then add or subtract the two equations to eliminate the term . An alternative motivation for the algebra is to eliminate the trig functions in front of by using the trig identity . At the very least this would result in an equation that is simple to solve for . ANSWER: Correct Congratulations on working this through. Now realize that in coordinate system a, which is aligned with the plane, the y-coordinate equation is , which leads immediately to the result obtained here for . CONCLUSION: A thoughtful examination of which coordinate system to choose can save a lot of algebra. Contact Forces Introduced Learning Goal: To introduce contact forces (normal and friction forces) and to understand that, except for friction forces under certain circumstances, these forces must be determined from: net Force = ma. Two solid objects cannot occupy the same space at the same time. Indeed, when the objects touch, they exert repulsive normal forces on each other, as well as frictional forces that resist their slipping relative to each other. These contact forces arise from a complex interplay between the electrostatic forces between the electrons and ions in the objects and the laws of quantum mechanics. As two surfaces are pushed together these forces increase exponentially over an atomic distance scale, easily becoming strong enough to distort the bulk material in the objects if they approach too close. In everyday experience, contact forces are limited by the deformation or acceleration of the objects, rather than by the fundamental interatomic forces. Hence, we can conclude the following: The magnitude of contact forces is determined by , that is, by the other forces on, and acceleration of, the contacting bodies. The only exception is that the frictional forces cannot exceed (although they can be smaller than this or even zero). Normal and friction forces Two types of contact forces operate in typical mechanics problems, the normal and frictional forces, usually designated by and (or , or something similar) respectively. These are the components of the overall contact force: perpendicular to and parallel to the plane of contact. Kinetic friction when surfaces slide cos  sin  Ff cos() sin() Fn sin2() + cos2 () = 1 Fn Fn = Fwcos() Fy = Fn − FW cos() = 0 Fn F = ma μn n f Ffric n f Typesetting math: 100% When one surface is sliding past the other, experiments show three things about the friction force (denoted ): The frictional force opposes the relative motion at the 1. point of contact, 2. is proportional to the normal force, and 3. the ratio of the magnitude of the frictional force to that of the normal force is fairly constant over a wide range of speeds. The constant of proportionality is called the coefficient of kinetic friction, often designated . As long as the sliding continues, the frictional force is then (valid when the surfaces slide by each other). Static friction when surfaces don’t slide When there is no relative motion of the surfaces, the frictional force can assume any value from zero up to a maximum , where is the coefficient of static friction. Invariably, is larger than , in agreement with the observation that when a force is large enough that something breaks loose and starts to slide, it often accelerates. The frictional force for surfaces with no relative motion is therefore (valid when the contacting surfaces have no relative motion). The actual magnitude and direction of the static friction force are such that it (together with other forces on the object) causes the object to remain motionless with respect to the contacting surface as long as the static friction force required does not exceed . The equation is valid only when the surfaces are on the verge of sliding. Part A When two objects slide by one another, which of the following statements about the force of friction between them, is true? ANSWER: Correct Part B fk fk μk fk = μkn μsn μs μs μk fs ! μsn μsn fs = μsn The frictional force is always equal to . The frictional force is always less than . The frictional force is determined by other forces on the objects so it can be either equal to or less than . μkn μkn μkn Typesetting math: 100% When two objects are in contact with no relative motion, which of the following statements about the frictional force between them, is true? ANSWER: Correct For static friction, the actual magnitude and direction of the friction force are such that it, together with any other forces present, will cause the object to have the observed acceleration. The magnitude of the force cannot exceed . If the magnitude of static friction needed to keep acceleration equal to zero exceeds , then the object will slide subject to the resistance of kinetic friction. Do not automatically assume that unless you are considering a situation in which the magnitude of the static friction force is as large as possible (i.e., when determining at what point an object will just begin to slip). Whether the actual magnitude of the friction force is 0, less than , or equal to depends on the magnitude of the other forces (if any) as well as the acceleration of the object through . Part C When a board with a box on it is slowly tilted to larger and larger angle, common experience shows that the box will at some point “break loose” and start to accelerate down the board. The box begins to slide once the component of gravity acting parallel to the board just begins to exceeds the maximum force of static friction. Which of the following is the most general explanation for why the box accelerates down the board? ANSWER: The frictional force is always equal to . The frictional force is always less than . The frictional force is determined by other forces on the objects so it can be either equal to or less than . μsn μsn μsn μsn μsn fs = μsn μsn μsn F = ma Fg The force of kinetic friction is smaller than that of maximum static friction, but remains the same. Once the box is moving, is smaller than the force of maximum static friction but larger than the force of kinetic friction. Once the box is moving, is larger than the force of maximum static friction. When the box is stationary, equals the force of static friction, but once the box starts moving, the sliding reduces the normal force, which in turn reduces the friction. Fg Fg Fg Fg Typesetting math: 100% Correct At the point when the box finally does “break loose,” you know that the component of the box’s weight that is parallel to the board just exceeds (i.e., this component of gravitational force on the box has just reached a magnitude such that the force of static friction, which has a maximum value of , can no longer oppose it.) For the box to then accelerate, there must be a net force on the box along the board. Thus, the component of the box’s weight parallel to the board must be greater than the force of kinetic friction. Therefore the force of kinetic friction must be less than the force of static friction which implies , as expected. Part D Consider a problem in which a car of mass is on a road tilted at an angle . The normal force Select the best answer. ANSWER: Correct The key point is that contact forces must be determined from Newton’s equation. In the problem described above, there is not enough information given to determine the normal force (e.g., the acceleration is unknown). Each of the answer options is valid under some conditions ( , the car is sliding down an icy incline, or the car is going around a banked turn), but in fact none is likely to be correct if there are other forces on the car or if the car is accelerating. Do not memorize values for the normal force valid in different problems–you must determine from . Problem 6.17 Bonnie and Clyde are sliding a 323 bank safe across the floor to their getaway car. The safe slides with a constant speed if Clyde pushes from behind with 375 of force while Bonnie pulls forward on a rope with 335 of force. μsn μsn μkn μsn μk < μs M  is found using n = Mg n = Mg cos() n = Mg cos() F  = Ma  = 0 n F = ma kg N N Typesetting math: 100% Part A What is the safe's coefficient of kinetic friction on the bank floor? ANSWER: Correct Problem 6.19 A crate is placed on a horizontal conveyor belt. The materials are such that and . Part A Draw a free-body diagram showing all the forces on the crate if the conveyer belt runs at constant speed. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded. ANSWER: 0.224 10 kg μs = 0.5 μk = 0.3 Typesetting math: 100% Correct Part B Draw a free-body diagram showing all the forces on the crate if the conveyer belt is speeding up. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded. ANSWER: Typesetting math: 100% Correct Part C What is the maximum acceleration the belt can have without the crate slipping? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct amax = 4.9 m s2 Typesetting math: 100% Problem 6.28 A 1100 steel beam is supported by two ropes. Part A What is the tension in rope 1? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the tension in rope 2? Express your answer to two significant figures and include the appropriate units. ANSWER: kg T1 = 7000 N Typesetting math: 100% Correct Problem 6.35 The position of a 1.4 mass is given by , where is in seconds. Part A What is the net horizontal force on the mass at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the net horizontal force on the mass at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 6.39 T2 = 4800 N kg x = (2t3 − 3t2 )m t t = 0 s F = -8.4 N t = 1 s F = 8.4 N Typesetting math: 100% A rifle with a barrel length of 61 fires a 8 bullet with a horizontal speed of 400 . The bullet strikes a block of wood and penetrates to a depth of 11 . Part A What resistive force (assumed to be constant) does the wood exert on the bullet? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B How long does it take the bullet to come to rest after entering the wood? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 6.45 You and your friend Peter are putting new shingles on a roof pitched at 21 . You're sitting on the very top of the roof when Peter, who is at the edge of the roof directly below you, 5.0 away, asks you for the box of nails. Rather than carry the 2.0 box of nails down to Peter, you decide to give the box a push and have it slide down to him. Part A If the coefficient of kinetic friction between the box and the roof is 0.55, with what speed should you push the box to have it gently come to rest right at the edge of the roof? Express your answer to two significant figures and include the appropriate units. cm g m/s cm fk = 5800 N = 5.5×10−4 t s  m kg Typesetting math: 100% ANSWER: Correct Problem 6.54 The 2.0 wood box in the figure slides down a vertical wood wall while you push on it at a 45 angle. Part A What magnitude of force should you apply to cause the box to slide down at a constant speed? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct v = 3.9 ms kg  F = 23 N Typesetting math: 100% Score Summary: Your score on this assignment is 98.8%. You received 114.57 out of a possible total of 116 points. Typesetting math: 100%

Assignment 5 Due: 11:59pm on Wednesday, March 5, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Conceptual Question 6.13 A hand presses down on the book in the figure. Part A Is the normal force of the table on the book larger than, smaller than, or equal to ? ANSWER: Correct mg Equal to Larger than Smaller than mg mg mg Problem 6.2 The three ropes in the figure are tied to a small, very light ring. Two of these ropes are anchored to walls at right angles with the tensions shown in the figure. Part A What is the magnitude of the tension in the third rope? Express your answer using two significant figures. ANSWER: Correct Part B What is the direction of the tension in the third rope? Express your answer using two significant figures. T  3 T3 = 94 N T  3 Typesetting math: 100% ANSWER: Correct The Normal Force When an object rests on a surface, there is always a force perpendicular to the surface; we call this the normal force, denoted by . The two questions to the right will explore the normal force. Part A A man attempts to pick up his suitcase of weight by pulling straight up on the handle. However, he is unable to lift the suitcase from the floor. Which statement about the magnitude of the normal force acting on the suitcase is true during the time that the man pulls upward on the suitcase? Hint 1. How to approach this problem First, identify the forces that act on the suitcase and draw a free-body diagram. Then use the fact that the suitcase is in equilibrium, , to examine how the forces acting on the suitcase relate to each other. Hint 2. Identify the correct free-body diagram Which of the figures represents the free-body diagram of the suitcase while the man is pulling on the handle with a force of magnitude ? = 58   below horizontal n ws n F = 0 fpull Typesetting math: 100% ANSWER: ANSWER: Correct Part B A B C D The magnitude of the normal force is equal to the magnitude of the weight of the suitcase. The magnitude of the normal force is equal to the magnitude of the weight of the suitcase minus the magnitude of the force of the pull. The magnitude of the normal force is equal to the sum of the magnitude of the force of the pull and the magnitude of the suitcase’s weight. The magnitude of the normal force is greater than the magnitude of the weight of the suitcase. Typesetting math: 100% Now assume that the man of weight is tired and decides to sit on his suitcase. Which statement about the magnitude of the normal force acting on the suitcase is true during the time that the man is sitting on the suitcase? Hint 1. Identify the correct free-body diagram. Which of the figures represents the free-body diagram while the man is sitting atop the suitcase? Here the vector labeled is a force that has the same magnitude as the man’s weight. ANSWER: wm n wm Typesetting math: 100% ANSWER: Correct Recognize that the normal force acting on an object is not always equal to the weight of that object. This is an important point to understand. Problem 6.5 A construction worker with a weight of 880 stands on a roof that is sloped at 18 . Part A What is the magnitude of the normal force of the roof on the worker? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct A B C D The magnitude of the normal force is equal to the magnitude of the suitcase’s weight. The magnitude of the normal force is equal to the magnitude of the suitcase’s weight minus the magnitude of the man’s weight. The magnitude of the normal force is equal to the sum of the magnitude of the man’s weight and the magnitude of the suitcase’s weight. The magnitude of the normal force is less than the magnitude of the suitcase’s weight. N  n = 840 N Typesetting math: 100% Problem 6.6 In each of the two free-body diagrams, the forces are acting on a 3.0 object. Part A For diagram , find the value of , the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B For diagram the part A, find the value of the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: kg ax x ax = -0.67 m s2 ay, y Typesetting math: 100% Correct Part C For diagram , find the value of , the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part D For diagram the part C, find the value of , the -component of the acceleration. Express your answer to two significant figures and include the appropriate units. ANSWER: ay = 0 m s2 ax x ax = 0.67 m s2 ay y Typesetting math: 100% Correct Problem 6.7 In each of the two free-body diagrams, the forces are acting on a 3.0 object. Part A Find the value of , the component of the acceleration in diagram (a). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct ay = 0 m s2 kg ax x ax = 0.99 m s2 Typesetting math: 100% Part B Find the value of , the component of the acceleration in diagram (a). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C Find the value of , the component of the acceleration in diagram (b). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part D Find the value of , the component of the acceleration in diagram (b). Express your answer to two significant figures and include the appropriate units. ANSWER: Correct ay y ay = 0 m s2 ax x ax = -0.18 m s2 ay y ay = 0 m s2 Typesetting math: 100% Problem 6.10 A horizontal rope is tied to a 53.0 box on frictionless ice. What is the tension in the rope if: Part A The box is at rest? Express your answer as an integer and include the appropriate units. ANSWER: Correct Part B The box moves at a steady = 4.80 ? Express your answer as an integer and include the appropriate units. ANSWER: Correct Part C The box = 4.80 and = 4.60 ? Express your answer to three significant figures and include the appropriate units. ANSWER: kg T = 0 N vx m/s T = 0 N vx m/s ax m/s2 Typesetting math: 100% Correct Problem 6.14 It takes the elevator in a skyscraper 4.5 to reach its cruising speed of 11 . A 60 passenger gets aboard on the ground floor. Part A What is the passenger’s weight before the elevator starts moving? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the passenger’s weight while the elevator is speeding up? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part C What is the passenger’s weight after the elevator reaches its cruising speed? T = 244 N s m/s kg w = 590 N w = 730 N Typesetting math: 100% Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Block on an Incline A block lies on a plane raised an angle from the horizontal. Three forces act upon the block: , the force of gravity; , the normal force; and , the force of friction. The coefficient of friction is large enough to prevent the block from sliding . Part A Consider coordinate system a, with the x axis along the plane. Which forces lie along the axes? ANSWER: w = 590 N  F  w F n F  f Typesetting math: 100% Correct Part B Which forces lie along the axes of the coordinate system b, in which the y axis is vertical? ANSWER: Correct only only only and and and and and F  f F  n F  w F  f F  n F  f F  w F  n F w F  f F  n F w only only only and and and and and F  f F  n F  w F  f F  n F  f F  w F  n F w F  f F  n F w Typesetting math: 100% Usually the best advice is to choose coordinate system so that the acceleration of the system is directly along one of the coordinate axes. If the system isn’t accelerating, then you are better off choosing the coordinate system with the most vectors along the coordinate axes. But now you are going to ignore that advice. You will find the normal force, , using vertical coordinate system b. In these coordinates you will find the magnitude appearing in both the x and y equations, each multiplied by a trigonometric function. Part C Because the block is not moving, the sum of the y components of the forces acting on the block must be zero. Find an expression for the sum of the y components of the forces acting on the block, using coordinate system b. Express your answer in terms of some or all of the variables , , , and . Hint 1. Find the y component of Write an expression for , the y component of the force , using coordinate system b. Express your answer in terms of and . Hint 1. Some geometry help – a useful angle The smaller angle between and the y-axis is also , as shown in the figure. ANSWER: F  n Fn Fn Ff Fw  F n Fny F  n Fn  F  n  Typesetting math: 100% Hint 2. Find the y component of Write an expression for , the y component of the force , using coordinate system b. Express your answer in terms of and . Hint 1. Some geometry help – a useful angle The smaller angle between and the x-axis is also , as shown in the figure. ANSWER: ANSWER: Fny = Fncos() F f Ffy F f Ff  F  f  Ffy = Ffsin() Fy = 0 = Fncos() + Ffsin() − Fw Typesetting math: 100% Correct Part D Because the block is not moving, the sum of the x components of the forces acting on the block must be zero. Find an expression for the sum of the x components of the forces acting on the block, using coordinate system b. Express your answer in terms of some or all of the variables , , , and . Hint 1. Find the x component of Write an expression for , the x component of the force , using coordinate system b. Express your answer in terms of and . ANSWER: ANSWER: Correct Part E To find the magnitude of the normal force, you must express in terms of since is an unknown. Using the equations you found in the two previous parts, find an expression for involving and but not . Hint 1. How to approach the problem From your answers to the previous two parts you should have two force equations ( and ). Combine these equations to eliminate . The key is to multiply the Fn Ff Fw  F n Fnx F  n Fn  Fnx = −Fnsin() Fx = 0 = −Fnsin() + Ffcos() Fn Fw Ff Fn Fw  Ff Typesetting math: 100% Fy = 0 Fx = 0 Ff equation for the y components by and the equation for the x components by , then add or subtract the two equations to eliminate the term . An alternative motivation for the algebra is to eliminate the trig functions in front of by using the trig identity . At the very least this would result in an equation that is simple to solve for . ANSWER: Correct Congratulations on working this through. Now realize that in coordinate system a, which is aligned with the plane, the y-coordinate equation is , which leads immediately to the result obtained here for . CONCLUSION: A thoughtful examination of which coordinate system to choose can save a lot of algebra. Contact Forces Introduced Learning Goal: To introduce contact forces (normal and friction forces) and to understand that, except for friction forces under certain circumstances, these forces must be determined from: net Force = ma. Two solid objects cannot occupy the same space at the same time. Indeed, when the objects touch, they exert repulsive normal forces on each other, as well as frictional forces that resist their slipping relative to each other. These contact forces arise from a complex interplay between the electrostatic forces between the electrons and ions in the objects and the laws of quantum mechanics. As two surfaces are pushed together these forces increase exponentially over an atomic distance scale, easily becoming strong enough to distort the bulk material in the objects if they approach too close. In everyday experience, contact forces are limited by the deformation or acceleration of the objects, rather than by the fundamental interatomic forces. Hence, we can conclude the following: The magnitude of contact forces is determined by , that is, by the other forces on, and acceleration of, the contacting bodies. The only exception is that the frictional forces cannot exceed (although they can be smaller than this or even zero). Normal and friction forces Two types of contact forces operate in typical mechanics problems, the normal and frictional forces, usually designated by and (or , or something similar) respectively. These are the components of the overall contact force: perpendicular to and parallel to the plane of contact. Kinetic friction when surfaces slide cos  sin  Ff cos() sin() Fn sin2() + cos2 () = 1 Fn Fn = Fwcos() Fy = Fn − FW cos() = 0 Fn F = ma μn n f Ffric n f Typesetting math: 100% When one surface is sliding past the other, experiments show three things about the friction force (denoted ): The frictional force opposes the relative motion at the 1. point of contact, 2. is proportional to the normal force, and 3. the ratio of the magnitude of the frictional force to that of the normal force is fairly constant over a wide range of speeds. The constant of proportionality is called the coefficient of kinetic friction, often designated . As long as the sliding continues, the frictional force is then (valid when the surfaces slide by each other). Static friction when surfaces don’t slide When there is no relative motion of the surfaces, the frictional force can assume any value from zero up to a maximum , where is the coefficient of static friction. Invariably, is larger than , in agreement with the observation that when a force is large enough that something breaks loose and starts to slide, it often accelerates. The frictional force for surfaces with no relative motion is therefore (valid when the contacting surfaces have no relative motion). The actual magnitude and direction of the static friction force are such that it (together with other forces on the object) causes the object to remain motionless with respect to the contacting surface as long as the static friction force required does not exceed . The equation is valid only when the surfaces are on the verge of sliding. Part A When two objects slide by one another, which of the following statements about the force of friction between them, is true? ANSWER: Correct Part B fk fk μk fk = μkn μsn μs μs μk fs ! μsn μsn fs = μsn The frictional force is always equal to . The frictional force is always less than . The frictional force is determined by other forces on the objects so it can be either equal to or less than . μkn μkn μkn Typesetting math: 100% When two objects are in contact with no relative motion, which of the following statements about the frictional force between them, is true? ANSWER: Correct For static friction, the actual magnitude and direction of the friction force are such that it, together with any other forces present, will cause the object to have the observed acceleration. The magnitude of the force cannot exceed . If the magnitude of static friction needed to keep acceleration equal to zero exceeds , then the object will slide subject to the resistance of kinetic friction. Do not automatically assume that unless you are considering a situation in which the magnitude of the static friction force is as large as possible (i.e., when determining at what point an object will just begin to slip). Whether the actual magnitude of the friction force is 0, less than , or equal to depends on the magnitude of the other forces (if any) as well as the acceleration of the object through . Part C When a board with a box on it is slowly tilted to larger and larger angle, common experience shows that the box will at some point “break loose” and start to accelerate down the board. The box begins to slide once the component of gravity acting parallel to the board just begins to exceeds the maximum force of static friction. Which of the following is the most general explanation for why the box accelerates down the board? ANSWER: The frictional force is always equal to . The frictional force is always less than . The frictional force is determined by other forces on the objects so it can be either equal to or less than . μsn μsn μsn μsn μsn fs = μsn μsn μsn F = ma Fg The force of kinetic friction is smaller than that of maximum static friction, but remains the same. Once the box is moving, is smaller than the force of maximum static friction but larger than the force of kinetic friction. Once the box is moving, is larger than the force of maximum static friction. When the box is stationary, equals the force of static friction, but once the box starts moving, the sliding reduces the normal force, which in turn reduces the friction. Fg Fg Fg Fg Typesetting math: 100% Correct At the point when the box finally does “break loose,” you know that the component of the box’s weight that is parallel to the board just exceeds (i.e., this component of gravitational force on the box has just reached a magnitude such that the force of static friction, which has a maximum value of , can no longer oppose it.) For the box to then accelerate, there must be a net force on the box along the board. Thus, the component of the box’s weight parallel to the board must be greater than the force of kinetic friction. Therefore the force of kinetic friction must be less than the force of static friction which implies , as expected. Part D Consider a problem in which a car of mass is on a road tilted at an angle . The normal force Select the best answer. ANSWER: Correct The key point is that contact forces must be determined from Newton’s equation. In the problem described above, there is not enough information given to determine the normal force (e.g., the acceleration is unknown). Each of the answer options is valid under some conditions ( , the car is sliding down an icy incline, or the car is going around a banked turn), but in fact none is likely to be correct if there are other forces on the car or if the car is accelerating. Do not memorize values for the normal force valid in different problems–you must determine from . Problem 6.17 Bonnie and Clyde are sliding a 323 bank safe across the floor to their getaway car. The safe slides with a constant speed if Clyde pushes from behind with 375 of force while Bonnie pulls forward on a rope with 335 of force. μsn μsn μkn μsn μk < μs M  is found using n = Mg n = Mg cos() n = Mg cos() F  = Ma  = 0 n F = ma kg N N Typesetting math: 100% Part A What is the safe's coefficient of kinetic friction on the bank floor? ANSWER: Correct Problem 6.19 A crate is placed on a horizontal conveyor belt. The materials are such that and . Part A Draw a free-body diagram showing all the forces on the crate if the conveyer belt runs at constant speed. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded. ANSWER: 0.224 10 kg μs = 0.5 μk = 0.3 Typesetting math: 100% Correct Part B Draw a free-body diagram showing all the forces on the crate if the conveyer belt is speeding up. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded. ANSWER: Typesetting math: 100% Correct Part C What is the maximum acceleration the belt can have without the crate slipping? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct amax = 4.9 m s2 Typesetting math: 100% Problem 6.28 A 1100 steel beam is supported by two ropes. Part A What is the tension in rope 1? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the tension in rope 2? Express your answer to two significant figures and include the appropriate units. ANSWER: kg T1 = 7000 N Typesetting math: 100% Correct Problem 6.35 The position of a 1.4 mass is given by , where is in seconds. Part A What is the net horizontal force on the mass at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B What is the net horizontal force on the mass at ? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 6.39 T2 = 4800 N kg x = (2t3 − 3t2 )m t t = 0 s F = -8.4 N t = 1 s F = 8.4 N Typesetting math: 100% A rifle with a barrel length of 61 fires a 8 bullet with a horizontal speed of 400 . The bullet strikes a block of wood and penetrates to a depth of 11 . Part A What resistive force (assumed to be constant) does the wood exert on the bullet? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Part B How long does it take the bullet to come to rest after entering the wood? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct Problem 6.45 You and your friend Peter are putting new shingles on a roof pitched at 21 . You're sitting on the very top of the roof when Peter, who is at the edge of the roof directly below you, 5.0 away, asks you for the box of nails. Rather than carry the 2.0 box of nails down to Peter, you decide to give the box a push and have it slide down to him. Part A If the coefficient of kinetic friction between the box and the roof is 0.55, with what speed should you push the box to have it gently come to rest right at the edge of the roof? Express your answer to two significant figures and include the appropriate units. cm g m/s cm fk = 5800 N = 5.5×10−4 t s  m kg Typesetting math: 100% ANSWER: Correct Problem 6.54 The 2.0 wood box in the figure slides down a vertical wood wall while you push on it at a 45 angle. Part A What magnitude of force should you apply to cause the box to slide down at a constant speed? Express your answer to two significant figures and include the appropriate units. ANSWER: Correct v = 3.9 ms kg  F = 23 N Typesetting math: 100% Score Summary: Your score on this assignment is 98.8%. You received 114.57 out of a possible total of 116 points. Typesetting math: 100%

Assignment 5 Due: 11:59pm on Wednesday, March 5, 2014 You … Read More...