After reading the supplement article on Business Analytics linked to the week 1 schedule, write an essay on how business analytics impacts you today, or its potential role in your chosen career path. Do research for your paper, or interview someone who works in your area. The goals of this paper are two-fold: (1) focus on high quality writing, using the COBE Writing Styles Guide for writing help and citations. (2) consider the importance of BI from a personal/work/career perspective.

After reading the supplement article on Business Analytics linked to the week 1 schedule, write an essay on how business analytics impacts you today, or its potential role in your chosen career path. Do research for your paper, or interview someone who works in your area. The goals of this paper are two-fold: (1) focus on high quality writing, using the COBE Writing Styles Guide for writing help and citations. (2) consider the importance of BI from a personal/work/career perspective.

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– 1 – Fall 2015 EECS 338 Assignment 2 Due: Oct. 1st, 2015 G. Ozsoyoglu Concurrent Programming with Semaphores; 140 points (100 pts) 1. Priority-based Searchers/Inserters/Deleters Problem without starvation. Three types of processes, namely, searchers, inserters, and deleters share access to a singly linked list L, and perform search, insert, or delete operations, respectively. The list L does not have duplicate values. a) Searchers merely search the list L, and report success (i.e., item searched is in L) or no-success (i.e., item searched is not in L) to a log file. Hence they can execute concurrently with each other. b) Inserters add new items to the end of the list L, and report success (i.e., item is not in L, and successfully inserted into L) or no-success (i.e., item is already in L, and no insertion takes place) to a log file. Insertions must be mutually exclusive to preclude two inserters from inserting new items at about the same time. However, one insert can proceed in parallel with any number of searches. c) Deleters remove items from anywhere in the list, and report success (i.e., the item is found in L and deleted) or no-success (i.e., item is not in L, and could not be deleted) to a log file. At most one deleter can access the list L at a time, and the deletion must be mutually exclusive with searches and insertions. d) Initial start. Searcher, inserter, and deleter processes are initially launched as follows. A user process that needs a search/insertion/deletion operation to the list L first forks a process, and then, in the forked process, performs an execv into a searcher/ inserter/deleter process. e) Log maintenance. Upon start, each searcher/inserter/deleter writes to a log file, recording the time of insertion, process id, process type (i.e., searcher, inserter, or deleter), and the item that is being searched/inserted/deleted. f) Termination. Upon successful or unsuccessful completion, each searcher/inserter/deleter writes to the same log file, recording the time and the result of its execution. g) Priority-based service between three types. Searchers, inserters, and deleters perform their search, insert, delete operations, respectively, on a priority basis (not on a first-come-first-serve (FCFS) basis) between separate process types (i.e., searchers, inserters, deleters) as follows. Searchers search with the highest priority; inserters insert with the second highest priority (except that one inserter can proceed in parallel with any number of searchers), and deleters delete with the lowest priority. h) FCFS service within a single type. Processes of the same type are serviced FCFS. As an example, among multiple inserters, the order of insertions into L is FCFS. Similarly, among multiple deleters, the order of deletions into L is FCFS. Note that, among searchers, while the start of search among searchers is FCFS, due to concurrent searcher execution, the completions of multiple searchers may not be FCFS. i) Starvation avoidance. In addition to the above priority-based search/insert/delete operations, the following starvation-avoidance rule is enforced. o After 10 consecutive searchers search the list L, if there is at least one waiting inserter or deleter then newly arriving searchers are blocked until (a) all waiting inserters are first serviced FCFS, and, then (b) all waiting deleters are serviced FCFS. Then, both the standard priority-based service between process types and the FCFS service within a process type resume. You are to specify a semaphore-based algorithm to synchronize searcher, inserter and deleter processes. Note:  Explain your algorithm.  Make sure to state any assumptions you make in your solution.  Specify the initial states of your variables and semaphores.  Specify whether your semaphores are binary or nonbinary.  Do not bother specifying algorithms for sequential tasks: simply specify a well-defined function/procedure (i.e., one with well-defined input/output/functional specification). – 2 – (40 pts) 2. Four-of-a-Kind Problem is defined as follows.  There is a deck of 24 cards, split into 6 different kinds, 4 cards of each kind.  There are 4 players (i.e., processes) ??,0≤?≤3; each player can hold 4 cards.  Between each pair of adjacent (i.e., seated next to each other) players, there is a pile of cards.  The game begins by o someone dealing four cards to each player, and putting two cards on the pile between each pair of adjacent players, and o ?0 starting the game. If ?0 has four-of-a-kind, ?0 wins. Whoever gets four-of-a-kind first wins.  Players take turns to play clockwise. That is, ?0 plays, ?1 plays, ?2 plays, ?3 plays, ?0 plays, etc.  Each player behaves as follows. o So long as no one has won, keep playing. o If it is my turn and no one has won:  Check for Four-of-a-Kind. If yes, claim victory. Otherwise discard a card into the pile on the right; pick up a card from the pile on the left; and, check again: If Four-of-a-Kind, claim victory; otherwise revise turn so that the next player plays and wait for your turn.  There are no ties; when a player has claimed victory, all other players stop (when their turns to play come up). You are to specify a semaphore-based algorithm to the Four-of-a-Kind problem. Note:  Explain your algorithm.  Make sure to state any assumptions you make in your solution.  Specify the initial states of your variables and semaphores.  Specify whether your semaphores are binary or nonbinary.  Do not bother specifying algorithms for sequential tasks: simply specify a well-defined function/procedure (i.e., one with well-defined input/output/functional specification). P1 P0 P2 P3 pile 1 pile 2 pile 3 pile 0

– 1 – Fall 2015 EECS 338 Assignment 2 Due: Oct. 1st, 2015 G. Ozsoyoglu Concurrent Programming with Semaphores; 140 points (100 pts) 1. Priority-based Searchers/Inserters/Deleters Problem without starvation. Three types of processes, namely, searchers, inserters, and deleters share access to a singly linked list L, and perform search, insert, or delete operations, respectively. The list L does not have duplicate values. a) Searchers merely search the list L, and report success (i.e., item searched is in L) or no-success (i.e., item searched is not in L) to a log file. Hence they can execute concurrently with each other. b) Inserters add new items to the end of the list L, and report success (i.e., item is not in L, and successfully inserted into L) or no-success (i.e., item is already in L, and no insertion takes place) to a log file. Insertions must be mutually exclusive to preclude two inserters from inserting new items at about the same time. However, one insert can proceed in parallel with any number of searches. c) Deleters remove items from anywhere in the list, and report success (i.e., the item is found in L and deleted) or no-success (i.e., item is not in L, and could not be deleted) to a log file. At most one deleter can access the list L at a time, and the deletion must be mutually exclusive with searches and insertions. d) Initial start. Searcher, inserter, and deleter processes are initially launched as follows. A user process that needs a search/insertion/deletion operation to the list L first forks a process, and then, in the forked process, performs an execv into a searcher/ inserter/deleter process. e) Log maintenance. Upon start, each searcher/inserter/deleter writes to a log file, recording the time of insertion, process id, process type (i.e., searcher, inserter, or deleter), and the item that is being searched/inserted/deleted. f) Termination. Upon successful or unsuccessful completion, each searcher/inserter/deleter writes to the same log file, recording the time and the result of its execution. g) Priority-based service between three types. Searchers, inserters, and deleters perform their search, insert, delete operations, respectively, on a priority basis (not on a first-come-first-serve (FCFS) basis) between separate process types (i.e., searchers, inserters, deleters) as follows. Searchers search with the highest priority; inserters insert with the second highest priority (except that one inserter can proceed in parallel with any number of searchers), and deleters delete with the lowest priority. h) FCFS service within a single type. Processes of the same type are serviced FCFS. As an example, among multiple inserters, the order of insertions into L is FCFS. Similarly, among multiple deleters, the order of deletions into L is FCFS. Note that, among searchers, while the start of search among searchers is FCFS, due to concurrent searcher execution, the completions of multiple searchers may not be FCFS. i) Starvation avoidance. In addition to the above priority-based search/insert/delete operations, the following starvation-avoidance rule is enforced. o After 10 consecutive searchers search the list L, if there is at least one waiting inserter or deleter then newly arriving searchers are blocked until (a) all waiting inserters are first serviced FCFS, and, then (b) all waiting deleters are serviced FCFS. Then, both the standard priority-based service between process types and the FCFS service within a process type resume. You are to specify a semaphore-based algorithm to synchronize searcher, inserter and deleter processes. Note:  Explain your algorithm.  Make sure to state any assumptions you make in your solution.  Specify the initial states of your variables and semaphores.  Specify whether your semaphores are binary or nonbinary.  Do not bother specifying algorithms for sequential tasks: simply specify a well-defined function/procedure (i.e., one with well-defined input/output/functional specification). – 2 – (40 pts) 2. Four-of-a-Kind Problem is defined as follows.  There is a deck of 24 cards, split into 6 different kinds, 4 cards of each kind.  There are 4 players (i.e., processes) ??,0≤?≤3; each player can hold 4 cards.  Between each pair of adjacent (i.e., seated next to each other) players, there is a pile of cards.  The game begins by o someone dealing four cards to each player, and putting two cards on the pile between each pair of adjacent players, and o ?0 starting the game. If ?0 has four-of-a-kind, ?0 wins. Whoever gets four-of-a-kind first wins.  Players take turns to play clockwise. That is, ?0 plays, ?1 plays, ?2 plays, ?3 plays, ?0 plays, etc.  Each player behaves as follows. o So long as no one has won, keep playing. o If it is my turn and no one has won:  Check for Four-of-a-Kind. If yes, claim victory. Otherwise discard a card into the pile on the right; pick up a card from the pile on the left; and, check again: If Four-of-a-Kind, claim victory; otherwise revise turn so that the next player plays and wait for your turn.  There are no ties; when a player has claimed victory, all other players stop (when their turns to play come up). You are to specify a semaphore-based algorithm to the Four-of-a-Kind problem. Note:  Explain your algorithm.  Make sure to state any assumptions you make in your solution.  Specify the initial states of your variables and semaphores.  Specify whether your semaphores are binary or nonbinary.  Do not bother specifying algorithms for sequential tasks: simply specify a well-defined function/procedure (i.e., one with well-defined input/output/functional specification). P1 P0 P2 P3 pile 1 pile 2 pile 3 pile 0

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Faculty of Science Technology and Engineering Department of Physics Senior Laboratory Faraday rotation AIM To show that optical activity is induced in a certain type of glass when it is in a magnetic field. To investigate the degree of rotation of linearly polarised light as a function of the applied magnetic field and hence determine a parameter which is characteristic of each material and known as Verdet’s constant. BACKGROUND INFORMATION A brief description of the properties and production of polarised light is given in the section labelled: Notes on polarisation. This should be read before proceeding with this experiment. Additional details may be found in the references listed at the end of this experiment. Whereas some materials, such as quartz, are naturally optically active, optical activity can be induced in others by the application of a magnetic field. For such materials, the angle through which the plane of polarisation of a linearly polarised beam is rotated () depends on the thickness of the sample (L), the strength of the magnetic field (B) and on the properties of the particular material. The latter is described by means of a parameter introduced by Verdet, which is wavelength dependent. Thus:  = V B L Lamp Polariser Solenoid Polariser Glass rod A Solenoid power supply Viewing mirror EXPERIMENTAL PROCEDURE The experimental arrangement is shown in the diagram. Unpolarised white light is produced by a hot filament and viewed using a mirror. • The light from the globe passes through two polarisers as well as the specially doped glass rod. Select one of the colour filters provided and place in the light path. Each of these filters transmits a relatively narrow band of wavelengths centred around a dominant wavelength as listed in the table. Filter No. Dominant Wavelength 98 4350 Å 50 4500 75 4900 58 5300 72 B 6060 92 6700 With the power supply for the coil switched off, (do not simply turn the potentiometer to zero: this still allows some current to flow) adjust one of the polarisers until minimum light is transmitted to the mirror. Minimum transmission can be determined visually. • Decide which polariser you will work with and do not alter the other one during the measurements. • The magnetic field is generated by a current in a solenoid (coil) placed around the glass rod. As the current in the coil is increased, the magnitude of the magnetic field will increase as shown on the calibration curve below. The degree of optical activity will also increase, resulting in some angle of rotation of the plane of polarisation. Hence you will need to rotate your chosen polariser to regain a minimum setting. 0 1 2 3 4 5 0.00 0.02 0.04 0.06 0.08 I (amps) B (tesla) Magnetic field (B) produced by current (I) in solenoid • Record the rotation angle () for coil currents of 0,1,2,3,4 and 5 amps. Avoid having the current in the coil switched on except when measurements are actually being taken as it can easily overheat. If the coil becomes too hot to touch, switch it off and wait for it to cool before proceeding. • Plot  as a function of B and, given that the length of the glass rod is 30 cm, determine Verdet’s constant for this material at the wavelength () in use. • Repeat the experiment for each of the wavelengths available using the filter set provided. • Calculate the logarithm for each V and  and tabulate the results. By plotting log V against log , determine the relationship between V and . [Hint: m log(x) = log (xm) and log(xy) = log(x) + log(y)]. • Calculate the errors involved in your determination of V. The uncertainty in a value of B may be taken as the uncertainty in reading the scale of the calibration curve) • The magnetic field direction can be reversed by reversing the direction of current flow in the coil. Describe the effect of this reversal and provide an explanation. Reference Optics Hecht.

Faculty of Science Technology and Engineering Department of Physics Senior Laboratory Faraday rotation AIM To show that optical activity is induced in a certain type of glass when it is in a magnetic field. To investigate the degree of rotation of linearly polarised light as a function of the applied magnetic field and hence determine a parameter which is characteristic of each material and known as Verdet’s constant. BACKGROUND INFORMATION A brief description of the properties and production of polarised light is given in the section labelled: Notes on polarisation. This should be read before proceeding with this experiment. Additional details may be found in the references listed at the end of this experiment. Whereas some materials, such as quartz, are naturally optically active, optical activity can be induced in others by the application of a magnetic field. For such materials, the angle through which the plane of polarisation of a linearly polarised beam is rotated () depends on the thickness of the sample (L), the strength of the magnetic field (B) and on the properties of the particular material. The latter is described by means of a parameter introduced by Verdet, which is wavelength dependent. Thus:  = V B L Lamp Polariser Solenoid Polariser Glass rod A Solenoid power supply Viewing mirror EXPERIMENTAL PROCEDURE The experimental arrangement is shown in the diagram. Unpolarised white light is produced by a hot filament and viewed using a mirror. • The light from the globe passes through two polarisers as well as the specially doped glass rod. Select one of the colour filters provided and place in the light path. Each of these filters transmits a relatively narrow band of wavelengths centred around a dominant wavelength as listed in the table. Filter No. Dominant Wavelength 98 4350 Å 50 4500 75 4900 58 5300 72 B 6060 92 6700 With the power supply for the coil switched off, (do not simply turn the potentiometer to zero: this still allows some current to flow) adjust one of the polarisers until minimum light is transmitted to the mirror. Minimum transmission can be determined visually. • Decide which polariser you will work with and do not alter the other one during the measurements. • The magnetic field is generated by a current in a solenoid (coil) placed around the glass rod. As the current in the coil is increased, the magnitude of the magnetic field will increase as shown on the calibration curve below. The degree of optical activity will also increase, resulting in some angle of rotation of the plane of polarisation. Hence you will need to rotate your chosen polariser to regain a minimum setting. 0 1 2 3 4 5 0.00 0.02 0.04 0.06 0.08 I (amps) B (tesla) Magnetic field (B) produced by current (I) in solenoid • Record the rotation angle () for coil currents of 0,1,2,3,4 and 5 amps. Avoid having the current in the coil switched on except when measurements are actually being taken as it can easily overheat. If the coil becomes too hot to touch, switch it off and wait for it to cool before proceeding. • Plot  as a function of B and, given that the length of the glass rod is 30 cm, determine Verdet’s constant for this material at the wavelength () in use. • Repeat the experiment for each of the wavelengths available using the filter set provided. • Calculate the logarithm for each V and  and tabulate the results. By plotting log V against log , determine the relationship between V and . [Hint: m log(x) = log (xm) and log(xy) = log(x) + log(y)]. • Calculate the errors involved in your determination of V. The uncertainty in a value of B may be taken as the uncertainty in reading the scale of the calibration curve) • The magnetic field direction can be reversed by reversing the direction of current flow in the coil. Describe the effect of this reversal and provide an explanation. Reference Optics Hecht.

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Critical Essay Guidelines FORMAT: Prepare your paper as a Microsoft Word file. Single-space the body of your paper; you may double-space between the headings (Introduction, Background Explanation and Critical Evaluation) described below. Use 1” margins on all sides. Use a font that is no larger than Times New Roman at 12 pt. and no smaller than Times New Roman at 10 pt. Put your name, course name, section and the date in a header on top of all pages. Include page numbers. LENGTH, TOPIC, ETC.: Write a 2 – 3 page (single-spaced) (1500 words) critical response on your topic. Back up your discussion with direct quotation from the relevant text, preferably short quotes, such as single sentences and (even better) crucial phrases. Leave out words or phrases using…ellipses…, etc. Less than 1/4 page total of your paper should be direct quotation. Cite any direct quotes simply by giving text title and page number in parentheses; the page number will either be from the textbook or what’s posted on Blackboard. For example, such a citation might look like: (Schoedinger, 25). Include a “Works Cited” page at the end of your paper citing the primary philosophic text from Schoedinger’s textbook. No other sources should be used. Treat your intended audience as someone who has some familiarity with philosophy generally, but no familiarity with the details of what you are writing on. STRUCTURE: In this critical response, you will do all and only the following three things, putting each under its OWN SECTION HEADING: A. INTRODUCTION Begin with a one-sentence introductory paragraph where you very briefly say what you will be doing in the rest of the critical response, one which has the exact form: “In this critical response, I will consider <insert chosen topic>, and then I will argue that <insert statement of main thesis>.” For example: “In this critical response, I will consider Socrates’ views on a worthwhile life, and then I will argue that the worthwhile life is nothing more or less than the life of pleasure.” B. BACKGROUND EXPLANATION Explain (in one-half to 1 page), as clearly as you can, the background to your chosen topic, including any relevant discussion in the text, and also including any relevant theories, arguments, objections, crucial notions and distinctions, etc. C. CRITICAL EVALUATION Critically evaluate (in 1½ – 2 pages) your chosen topic. This involves explaining and defending your thesis on the topic. In doing this, address relevant material from your “ Background Explanation” section. Also, you are encouraged (but not required) to anticipate potential objections and reply to them. Throughout your critical evaluation, pay careful attention (even if just informally) to the criteria of a good argument. This applies both when you are considering others’ arguments and when you are giving your own. GRADING: Grading will be based partly on whether or not you have successfully followed the instructions above (including the format requirements). Each defect in terms of failure to satisfy the instructions will cost you points. Any paper which completely ignores all instructions, however, will receive a zero. Barring prior consent from me or documented and sufficiently excusing special contingency, late papers will be graded in accord with the late policy on the syllabus. Grading will also be based on the writing quality. Here I have in mind things like: is the paper clear, concise, grammatical and accurate? Does it provide necessary explanations and avoid irrelevant material?

Critical Essay Guidelines FORMAT: Prepare your paper as a Microsoft Word file. Single-space the body of your paper; you may double-space between the headings (Introduction, Background Explanation and Critical Evaluation) described below. Use 1” margins on all sides. Use a font that is no larger than Times New Roman at 12 pt. and no smaller than Times New Roman at 10 pt. Put your name, course name, section and the date in a header on top of all pages. Include page numbers. LENGTH, TOPIC, ETC.: Write a 2 – 3 page (single-spaced) (1500 words) critical response on your topic. Back up your discussion with direct quotation from the relevant text, preferably short quotes, such as single sentences and (even better) crucial phrases. Leave out words or phrases using…ellipses…, etc. Less than 1/4 page total of your paper should be direct quotation. Cite any direct quotes simply by giving text title and page number in parentheses; the page number will either be from the textbook or what’s posted on Blackboard. For example, such a citation might look like: (Schoedinger, 25). Include a “Works Cited” page at the end of your paper citing the primary philosophic text from Schoedinger’s textbook. No other sources should be used. Treat your intended audience as someone who has some familiarity with philosophy generally, but no familiarity with the details of what you are writing on. STRUCTURE: In this critical response, you will do all and only the following three things, putting each under its OWN SECTION HEADING: A. INTRODUCTION Begin with a one-sentence introductory paragraph where you very briefly say what you will be doing in the rest of the critical response, one which has the exact form: “In this critical response, I will consider , and then I will argue that .” For example: “In this critical response, I will consider Socrates’ views on a worthwhile life, and then I will argue that the worthwhile life is nothing more or less than the life of pleasure.” B. BACKGROUND EXPLANATION Explain (in one-half to 1 page), as clearly as you can, the background to your chosen topic, including any relevant discussion in the text, and also including any relevant theories, arguments, objections, crucial notions and distinctions, etc. C. CRITICAL EVALUATION Critically evaluate (in 1½ – 2 pages) your chosen topic. This involves explaining and defending your thesis on the topic. In doing this, address relevant material from your “ Background Explanation” section. Also, you are encouraged (but not required) to anticipate potential objections and reply to them. Throughout your critical evaluation, pay careful attention (even if just informally) to the criteria of a good argument. This applies both when you are considering others’ arguments and when you are giving your own. GRADING: Grading will be based partly on whether or not you have successfully followed the instructions above (including the format requirements). Each defect in terms of failure to satisfy the instructions will cost you points. Any paper which completely ignores all instructions, however, will receive a zero. Barring prior consent from me or documented and sufficiently excusing special contingency, late papers will be graded in accord with the late policy on the syllabus. Grading will also be based on the writing quality. Here I have in mind things like: is the paper clear, concise, grammatical and accurate? Does it provide necessary explanations and avoid irrelevant material?

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When the sheep Dolly was successfully cloned, it was produced by growing an in vitro fertilized egg where the normal egg nucleus had been removed and replaced by a nucleus from an adult. Since this nucleus is from an old mature animal, we would expect it to ______. Interestingly, tests show that this did not happen, a fact that currently puzzles researchers. Select one: have additional Barr bodies be mutated have shorter telomeres have longer telomeres express transcription and translation more rapidly

When the sheep Dolly was successfully cloned, it was produced by growing an in vitro fertilized egg where the normal egg nucleus had been removed and replaced by a nucleus from an adult. Since this nucleus is from an old mature animal, we would expect it to ______. Interestingly, tests show that this did not happen, a fact that currently puzzles researchers. Select one: have additional Barr bodies be mutated have shorter telomeres have longer telomeres express transcription and translation more rapidly

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Watch the video, and then answer the questions below. http://www.youtube.com/watch?v=XUF-T5JubDg#t=49 According to the video, which of the three scholars accepted the invasion of Iraq? A. Realists and liberals tended to reject it, but the constructivists thought it was a good idea. B. Realists tended to reject it, but the constructivists and liberals thought it was a good idea. C. Liberals tended to reject it, but the realists and constructivists thought it was a good idea. D. All of the scholars rejected it. E. None of the scholars rejected it. Which of the following was NOT given as a reason to be concerned about the war in Iraq? A. First and foremost, peace needed to prevail. B. The invasion was form of moralizing or crusading. C. The invasion undermined respect for International law. D. The invasion didn’t serve clear U.S. interests. E. The situation had the potential to become a quagmire. In the video, one of the topics under discussion concerns democratic governance. How much do their views conflict? A. Caleb Gallemore and J.D. Bowen disagree, because democracy is a social construct. B. Randall Schweller and J.D. Bowen disagree, because one side believes that democracy is impossible to spread while the other thinks it may be possible. C. Randall Schweller and Caleb Gallemore disagree with J.D. Bowen, because the first two view the attempt to spread democracy as a moralizing crusade. D. J.D. Bowen and Randall Schweller disagree with Caleb Gallemore, who doesn’t think that democracy can be spread successfully. E. All of the authors agree on the possibility of establishing democracy in Iraq. What sorts of things were on the minds of constructivists considering the war in Iraq? A. the history of colonialism, tensions between Islam and the West, and the United States’ perceived role as a world leader B. whether the war served U.S. interests C. whether the Coalition of the Willing would have forces sufficient to topple Saddam Hussein D. the likelihood that the war would result in a quagmire E. the importance of promoting human rights Professor Bowen says that liberals disagreed about invading Iraq but agreed on the form of government to be established there. What was that form of government? A. a loose confederacy of tribes B. a constitutional monarchy with negotiated rights for minorities C. a communist dictatorship with religious tolerance D. a democracy with respect for human rights E. a long-term military installation with UN forces overseeing government functions

Watch the video, and then answer the questions below. http://www.youtube.com/watch?v=XUF-T5JubDg#t=49 According to the video, which of the three scholars accepted the invasion of Iraq? A. Realists and liberals tended to reject it, but the constructivists thought it was a good idea. B. Realists tended to reject it, but the constructivists and liberals thought it was a good idea. C. Liberals tended to reject it, but the realists and constructivists thought it was a good idea. D. All of the scholars rejected it. E. None of the scholars rejected it. Which of the following was NOT given as a reason to be concerned about the war in Iraq? A. First and foremost, peace needed to prevail. B. The invasion was form of moralizing or crusading. C. The invasion undermined respect for International law. D. The invasion didn’t serve clear U.S. interests. E. The situation had the potential to become a quagmire. In the video, one of the topics under discussion concerns democratic governance. How much do their views conflict? A. Caleb Gallemore and J.D. Bowen disagree, because democracy is a social construct. B. Randall Schweller and J.D. Bowen disagree, because one side believes that democracy is impossible to spread while the other thinks it may be possible. C. Randall Schweller and Caleb Gallemore disagree with J.D. Bowen, because the first two view the attempt to spread democracy as a moralizing crusade. D. J.D. Bowen and Randall Schweller disagree with Caleb Gallemore, who doesn’t think that democracy can be spread successfully. E. All of the authors agree on the possibility of establishing democracy in Iraq. What sorts of things were on the minds of constructivists considering the war in Iraq? A. the history of colonialism, tensions between Islam and the West, and the United States’ perceived role as a world leader B. whether the war served U.S. interests C. whether the Coalition of the Willing would have forces sufficient to topple Saddam Hussein D. the likelihood that the war would result in a quagmire E. the importance of promoting human rights Professor Bowen says that liberals disagreed about invading Iraq but agreed on the form of government to be established there. What was that form of government? A. a loose confederacy of tribes B. a constitutional monarchy with negotiated rights for minorities C. a communist dictatorship with religious tolerance D. a democracy with respect for human rights E. a long-term military installation with UN forces overseeing government functions

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Chapter 4 Practice Problems (Practice – no credit) Due: 11:59pm on Friday, February 14, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Advice for the Quarterback A quarterback is set up to throw the football to a receiver who is running with a constant velocity directly away from the quarterback and is now a distance away from the quarterback. The quarterback figures that the ball must be thrown at an angle to the horizontal and he estimates that the receiver must catch the ball a time interval after it is thrown to avoid having opposition players prevent the receiver from making the catch. In the following you may assume that the ball is thrown and caught at the same height above the level playing field. Assume that the y coordinate of the ball at the instant it is thrown or caught is and that the horizontal position of the quaterback is . Use for the magnitude of the acceleration due to gravity, and use the pictured inertial coordinate system when solving the problem. Part A Find , the vertical component of the velocity of the ball when the quarterback releases it. Express in terms of and . Hint 1. Equation of motion in y direction What is the expression for , the height of the ball as a function of time? Answer in terms of , , and . v r D  tc y = 0 x = 0 g v0y v0y tc g y(t) t g v0y ANSWER: Incorrect; Try Again Hint 2. Height at which the ball is caught, Remember that after time the ball was caught at the same height as it had been released. That is, . ANSWER: Answer Requested Part B Find , the initial horizontal component of velocity of the ball. Express your answer for in terms of , , and . Hint 1. Receiver’s position Find , the receiver’s position before he catches the ball. Answer in terms of , , and . ANSWER: Football’s position y(t) = v0yt− g 1 2 t2 y(tc) tc y(tc) = y0 = 0 v0y = gtc 2 v0x v0x D tc vr xr D vr tc xr = D + vrtc Typesetting math: 100% Find , the horizontal distance that the ball travels before reaching the receiver. Answer in terms of and . ANSWER: ANSWER: Answer Requested Part C Find the speed with which the quarterback must throw the ball. Answer in terms of , , , and . Hint 1. How to approach the problem Remember that velocity is a vector; from solving Parts A and B you have the two components, from which you can find the magnitude of this vector. ANSWER: Answer Requested Part D xc v0x tc xc = v0xtc v0x = + D tc vr v0 D tc vr g v0 = ( + ) + D tc vr 2 ( ) gtc 2 2 −−−−−−−−−−−−−−−−−−−  Typesetting math: 100% Assuming that the quarterback throws the ball with speed , find the angle above the horizontal at which he should throw it. Your solution should contain an inverse trig function (entered as asin, acos, or atan). Give your answer in terms of already known quantities, , , and . Hint 1. Find angle from and Think of velocity as a vector with Cartesian coordinates and . Find the angle that this vector would make with the x axis using the results of Parts A and B. ANSWER: Answer Requested Direction of Velocity at Various Times in Flight for Projectile Motion Conceptual Question For each of the motions described below, determine the algebraic sign (positive, negative, or zero) of the x component and y component of velocity of the object at the time specified. For all of the motions, the positive x axis points to the right and the positive y axis points upward. Alex, a mountaineer, must leap across a wide crevasse. The other side of the crevasse is below the point from which he leaps, as shown in the figure. Alex leaps horizontally and successfully makes the jump. v0  v0x v0y v0  v0x v0y v0xx^ v0yy^   = atan( ) v0y v0x Typesetting math: 100% Part A Determine the algebraic sign of Alex’s x velocity and y velocity at the instant he leaves the ground at the beginning of the jump. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Typesetting math: 100% Hint 1. Algebraic sign of velocity The algebraic sign of the velocity is determined solely by comparing the direction in which the object is moving with the direction that is defined to be positive. In this example, to the right is defined to be the positive x direction and upward the positive y direction. Therefore, any object moving to the right, whether speeding up, slowing down, or even simultaneously moving upward or downward, has a positive x velocity. Similarly, if the object is moving downward, regardless of any other aspect of its motion, its y velocity is negative. Hint 2. Sketch Alex’s initial velocity On the diagram below, sketch the vector representing Alex’s velocity the instant after he leaves the ground at the beginning of the jump. ANSWER: ANSWER: Typesetting math: 100% Answer Requested Part B Determine the algebraic signs of Alex’s x velocity and y velocity the instant before he lands at the end of the jump. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Typesetting math: 100% Hint 1. Sketch Alex’s final velocity On the diagram below, sketch the vector representing Alex’s velocity the instant before he safely lands on the other side of the crevasse. ANSWER: Answer Requested ANSWER: Answer Requested Typesetting math: 100% At the buzzer, a basketball player shoots a desperation shot. The ball goes in! Part C Determine the algebraic signs of the ball’s x velocity and y velocity the instant after it leaves the player’s hands. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Hint 1. Sketch the basketball’s initial velocity On the diagram below, sketch the vector representing the velocity of the basketball the instant after it leaves the player’s hands. ANSWER: Typesetting math: 100% ANSWER: Correct Part D Determine the algebraic signs of the ball’s x velocity and y velocity at the ball’s maximum height. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Hint 1. Sketch the basketball’s velocity at maximum height Typesetting math: 100% On the diagram below, sketch the vector representing the velocity of the basketball the instant it reaches its maximum height. ANSWER: ANSWER: Answer Requested PSS 4.1 Projectile Motion Problems Learning Goal: Typesetting math: 100% To practice Problem-Solving Strategy 4.1 for projectile motion problems. A rock thrown with speed 9.00 and launch angle 30.0 (above the horizontal) travels a horizontal distance of = 17.0 before hitting the ground. From what height was the rock thrown? Use the value = 9.810 for the free-fall acceleration. PROBLEM-SOLVING STRATEGY 4.1 Projectile motion problems MODEL: Make simplifying assumptions, such as treating the object as a particle. Is it reasonable to ignore air resistance? VISUALIZE: Use a pictorial representation. Establish a coordinate system with the x axis horizontal and the y axis vertical. Show important points in the motion on a sketch. Define symbols, and identify what you are trying to find. SOLVE: The acceleration is known: and . Thus, the problem becomes one of two-dimensional kinematics. The kinematic equations are , . is the same for the horizontal and vertical components of the motion. Find from one component, and then use that value for the other component. ASSESS: Check that your result has the correct units, is reasonable, and answers the question. Model Start by making simplifying assumptions: Model the rock as a particle in free fall. You can ignore air resistance because the rock is a relatively heavy object moving relatively slowly. Visualize Part A Which diagram represents an accurate sketch of the rock’s trajectory? Hint 1. The launch angle In a projectile’s motion, the angle of the initial velocity above the horizontal is called the launch angle. ANSWER: m/s  d m g m/s2 ax = 0 ay = −g xf = xi +vixt, yf = yi +viyt− g(t 1 2 )2 vfx = vix = constant, and vfy = viy − gt t t v i Typesetting math: 100% Typesetting math: 100% Correct Part B As stated in the strategy, choose a coordinate system where the x axis is horizontal and the y axis is vertical. Note that in the strategy, the y component of the projectile’s acceleration, , is taken to be negative. This implies that the positive y axis is upward. Use the same convention for your y axis, and take the positive x axis to be to the right. Where you choose your origin doesn’t change the answer to the question, but choosing an origin can make a problem easier to solve (even if only a bit). Usually it is nice if the majority of the quantities you are given and the quantity you are trying to solve for take positive values relative to your chosen origin. Given this goal, what location for the origin of the coordinate system would make this problem easiest? ANSWER: ay At ground level below the point where the rock is launched At the point where the rock strikes the ground At the peak of the trajectory At the point where the rock is released At ground level below the peak of the trajectory Typesetting math: 100% Correct It’s best to place the origin of the coordinate system at ground level below the launching point because in this way all the points of interest (the launching point and the landing point) will have positive coordinates. (Based on your experience, you know that it’s generally easier to work with positive coordinates.) Keep in mind, however, that this is an arbitrary choice. The correct solution of the problem will not depend on the location of the origin of your coordinate system. Now, define symbols representing initial and final position, velocity, and time. Your target variable is , the initial y coordinate of the rock. Your pictorial representation should be complete now, and similar to the picture below: Solve Part C Find the height from which the rock was launched. Express your answer in meters to three significant figures. yi yi Typesetting math: 100% Hint 1. How to approach the problem The time needed to move horizontally to the final position = 17.0 is the same time needed for the rock to rise from the initial position to the peak of its trajectory and then fall to the ground. Use the information you have about motion in the horizontal direction to solve for . Knowing this time will allow you to use the equations of motion for the vertical direction to solve for . Hint 2. Find the time spent in the air How long ( ) is the rock in the air? Express your answer in seconds to three significant figures. Hint 1. Determine which equation to use Which of the equations given in the strategy and shown below is the most appropriate to calculate the time the rock spent in the air? ANSWER: Hint 2. Find the x component of the initial velocity What is the x component of the rock’s initial velocity? Express your answer in meters per second to three significant figures. ANSWER: ANSWER: t xf = d m yi t yi t t xf = xi + vixt yf = yi + viyt− g(t 1 2 )2 vfy = viy − gt vix = 7.79 m/s Typesetting math: 100% Hint 3. Find the y component of the initial velocity What is the y component of the rock’s initial velocity? Express your answer in meters per second to three significant figures. ANSWER: ANSWER: Answer Requested Assess Part D A second rock is thrown straight upward with a speed 4.500 . If this rock takes 2.181 to fall to the ground, from what height was it released? Express your answer in meters to three significant figures. Hint 1. Identify the known variables What are the values of , , , and for the second rock? Take the positive y axis to be upward and the origin to be located on the ground where the rock lands. Express your answers to four significant figures in the units shown to the right, separated by commas. ANSWER: t = 2.18 s viy = 4.50 m/s yi = 13.5 m m/s s H yf viy t a Typesetting math: 100% Answer Requested Hint 2. Determine which equation to use to find the height Which equation should you use to find ? Keep in mind that if the positive y axis is upward and the origin is located on the ground, . ANSWER: ANSWER: Answer Requested Projectile motion is made up of two independent motions: uniform motion at constant velocity in the horizontal direction and free-fall motion in the vertical direction. Because both rocks were thrown with the same initial vertical velocity, 4.500 , and fell the same vertical distance of 13.5 , they were in the air for the same amount of time. This result was expected and helps to confirm that you did the calculation in Part C correctly. ± Arrow Hits Apple An arrow is shot at an angle of above the horizontal. The arrow hits a tree a horizontal distance away, at the same height above the ground as it was shot. Use for the magnitude of the acceleration due to gravity. Part A , , , = 0,4.500,2.181,-yf viy t a 9.810 m, m/s, s, m/s2 H yi = H yf = yi + viyt− g(t 1 2 )2 vfy = viy − gt = − 2g( − ) v2f y v2i y yf yi H = 13.5 m viy = m/s m  = 45 D = 220 m g = 9.8 m/s2 Typesetting math: 100% Find , the time that the arrow spends in the air. Answer numerically in seconds, to two significant figures. Hint 1. Find the initial upward component of velocity in terms of D. Introduce the (unknown) variables and for the initial components of velocity. Then use kinematics to relate them and solve for . What is the vertical component of the initial velocity? Express your answer symbolically in terms of and . Hint 1. Find Find the horizontal component of the initial velocity. Express your answer symbolically in terms of and given symbolic quantities. ANSWER: Hint 2. Find What is the vertical component of the initial velocity? Express your answer symbolically in terms of . ANSWER: ANSWER: ta vy0 vx0 ta vy0 ta D vx0 vx0 ta vx0 = D ta vy0 vy0 vx0 vy0 = vx0 vy0 = D ta Typesetting math: 100% Hint 2. Find the time of flight in terms of the initial vertical component of velocity. From the change in the vertical component of velocity, you should be able to find in terms of and . Give your answer in terms of and . Hint 1. Find When applied to the y-component of velocity, in this problem the formula for with constant acceleration is What is , the vertical component of velocity when the arrow hits the tree? Answer symbolically in terms of only. ANSWER: ANSWER: Hint 3. Put the algebra together to find symbolically. If you have an expression for the initial vertical velocity component in terms in terms of and , and another in terms of and , you should be able to eliminate this initial component to find an expression for Express your answer symbolically in terms of given variables. ANSWER: ta vy0 g vy0 g vy(ta) v(t) −g vy(t) = vy0 − g t vy(ta ) vy0 vy(ta) = −vy0 ta = 2vy0 g ta D ta g ta ta2 t2 = a 2D g Typesetting math: 100% ANSWER: Answer Requested Suppose someone drops an apple from a vertical distance of 6.0 meters, directly above the point where the arrow hits the tree. Part B How long after the arrow was shot should the apple be dropped, in order for the arrow to pierce the apple as the arrow hits the tree? Express your answer numerically in seconds, to two significant figures. Hint 1. When should the apple be dropped The apple should be dropped at the time equal to the total time it takes the arrow to reach the tree minus the time it takes the apple to fall 6.0 meters. Hint 2. Find the time it takes for the apple to fall 6.0 meters How long does it take an apple to fall 6.0 meters? Express your answer numerically in seconds, to two significant figures. ANSWER: Answer Requested ANSWER: ta = 6.7 s tf = 1.1 s td = 5.6 s Typesetting math: 100% Answer Requested Video Tutor: Ball Fired Upward from Accelerating Cart First, launch the video below. You will be asked to use your knowledge of physics to predict the outcome of an experiment. Then, close the video window and answer the questions at right. You can watch the video again at any point. Part A Consider the video you just watched. Suppose we replace the original launcher with one that fires the ball upward at twice the speed. We make no other changes. How far behind the cart will the ball land, compared to the distance in the original experiment? Hint 1. Determine how long the ball is in the air How will doubling the initial upward speed of the ball change the time the ball spends in the air? A kinematic equation may be helpful here. The time in the air will ANSWER: be cut in half. stay the same. double. quadruple. Typesetting math: 100% Hint 2. Determine the appropriate kinematic expression Which of the following kinematic equations correctly describes the horizontal distance between the ball and the cart at the moment the ball lands? The cart’s initial horizontal velocity is , its horizontal acceleration is , and is the time elapsed between launch and impact. ANSWER: ANSWER: Correct The ball will spend twice as much time in the air ( , where is the ball’s initial upward velocity), so it will land four times farther behind the cart: (where is the cart’s horizontal acceleration). Video Tutor: Ball Fired Upward from Moving Cart First, launch the video below. You will be asked to use your knowledge of physics to predict the outcome of an experiment. Then, close the video window and answer the questions at right. You can watch the video again at any point. d v0x ax t d = v0x t d = 1 2 axv0x t2 d = v0x t+ 1 2 axt2 d = 1 2 axt2 the same distance twice as far half as far four times as far by a factor not listed above t = 2v0y/g v0y d = 1 2 axt2 ax Typesetting math: 100% Part A The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistance. Hint 1. How to approach the problem While the crate is on the plane, it shares the plane’s velocity. What is the crate’s velocity immediately after it is released? Hint 2. What affects the motion of the crate? Gravity will accelerate the crate downward. What, if anything, affects the crate’s horizontal motion? (Keep in mind that we are told to ignore air resistance, even though that’s not very realistic in this situation.) ANSWER: Correct At the moment it is released, the crate shares the plane’s horizontal velocity. In the absence of air resistance, the crate would remain directly below the plane as it fell. Score Summary: Your score on this assignment is 0%. Before the plane is directly over the target After the plane has flown over the target When the plane is directly over the target Typesetting math: 100% You received 0 out of a possible total of 0 points. Typesetting math: 100%

Chapter 4 Practice Problems (Practice – no credit) Due: 11:59pm on Friday, February 14, 2014 You will receive no credit for items you complete after the assignment is due. Grading Policy Advice for the Quarterback A quarterback is set up to throw the football to a receiver who is running with a constant velocity directly away from the quarterback and is now a distance away from the quarterback. The quarterback figures that the ball must be thrown at an angle to the horizontal and he estimates that the receiver must catch the ball a time interval after it is thrown to avoid having opposition players prevent the receiver from making the catch. In the following you may assume that the ball is thrown and caught at the same height above the level playing field. Assume that the y coordinate of the ball at the instant it is thrown or caught is and that the horizontal position of the quaterback is . Use for the magnitude of the acceleration due to gravity, and use the pictured inertial coordinate system when solving the problem. Part A Find , the vertical component of the velocity of the ball when the quarterback releases it. Express in terms of and . Hint 1. Equation of motion in y direction What is the expression for , the height of the ball as a function of time? Answer in terms of , , and . v r D  tc y = 0 x = 0 g v0y v0y tc g y(t) t g v0y ANSWER: Incorrect; Try Again Hint 2. Height at which the ball is caught, Remember that after time the ball was caught at the same height as it had been released. That is, . ANSWER: Answer Requested Part B Find , the initial horizontal component of velocity of the ball. Express your answer for in terms of , , and . Hint 1. Receiver’s position Find , the receiver’s position before he catches the ball. Answer in terms of , , and . ANSWER: Football’s position y(t) = v0yt− g 1 2 t2 y(tc) tc y(tc) = y0 = 0 v0y = gtc 2 v0x v0x D tc vr xr D vr tc xr = D + vrtc Typesetting math: 100% Find , the horizontal distance that the ball travels before reaching the receiver. Answer in terms of and . ANSWER: ANSWER: Answer Requested Part C Find the speed with which the quarterback must throw the ball. Answer in terms of , , , and . Hint 1. How to approach the problem Remember that velocity is a vector; from solving Parts A and B you have the two components, from which you can find the magnitude of this vector. ANSWER: Answer Requested Part D xc v0x tc xc = v0xtc v0x = + D tc vr v0 D tc vr g v0 = ( + ) + D tc vr 2 ( ) gtc 2 2 −−−−−−−−−−−−−−−−−−−  Typesetting math: 100% Assuming that the quarterback throws the ball with speed , find the angle above the horizontal at which he should throw it. Your solution should contain an inverse trig function (entered as asin, acos, or atan). Give your answer in terms of already known quantities, , , and . Hint 1. Find angle from and Think of velocity as a vector with Cartesian coordinates and . Find the angle that this vector would make with the x axis using the results of Parts A and B. ANSWER: Answer Requested Direction of Velocity at Various Times in Flight for Projectile Motion Conceptual Question For each of the motions described below, determine the algebraic sign (positive, negative, or zero) of the x component and y component of velocity of the object at the time specified. For all of the motions, the positive x axis points to the right and the positive y axis points upward. Alex, a mountaineer, must leap across a wide crevasse. The other side of the crevasse is below the point from which he leaps, as shown in the figure. Alex leaps horizontally and successfully makes the jump. v0  v0x v0y v0  v0x v0y v0xx^ v0yy^   = atan( ) v0y v0x Typesetting math: 100% Part A Determine the algebraic sign of Alex’s x velocity and y velocity at the instant he leaves the ground at the beginning of the jump. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Typesetting math: 100% Hint 1. Algebraic sign of velocity The algebraic sign of the velocity is determined solely by comparing the direction in which the object is moving with the direction that is defined to be positive. In this example, to the right is defined to be the positive x direction and upward the positive y direction. Therefore, any object moving to the right, whether speeding up, slowing down, or even simultaneously moving upward or downward, has a positive x velocity. Similarly, if the object is moving downward, regardless of any other aspect of its motion, its y velocity is negative. Hint 2. Sketch Alex’s initial velocity On the diagram below, sketch the vector representing Alex’s velocity the instant after he leaves the ground at the beginning of the jump. ANSWER: ANSWER: Typesetting math: 100% Answer Requested Part B Determine the algebraic signs of Alex’s x velocity and y velocity the instant before he lands at the end of the jump. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Typesetting math: 100% Hint 1. Sketch Alex’s final velocity On the diagram below, sketch the vector representing Alex’s velocity the instant before he safely lands on the other side of the crevasse. ANSWER: Answer Requested ANSWER: Answer Requested Typesetting math: 100% At the buzzer, a basketball player shoots a desperation shot. The ball goes in! Part C Determine the algebraic signs of the ball’s x velocity and y velocity the instant after it leaves the player’s hands. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Hint 1. Sketch the basketball’s initial velocity On the diagram below, sketch the vector representing the velocity of the basketball the instant after it leaves the player’s hands. ANSWER: Typesetting math: 100% ANSWER: Correct Part D Determine the algebraic signs of the ball’s x velocity and y velocity at the ball’s maximum height. Type the algebraic signs of the x velocity and the y velocity separated by a comma (examples: +,- and 0,+). Hint 1. Sketch the basketball’s velocity at maximum height Typesetting math: 100% On the diagram below, sketch the vector representing the velocity of the basketball the instant it reaches its maximum height. ANSWER: ANSWER: Answer Requested PSS 4.1 Projectile Motion Problems Learning Goal: Typesetting math: 100% To practice Problem-Solving Strategy 4.1 for projectile motion problems. A rock thrown with speed 9.00 and launch angle 30.0 (above the horizontal) travels a horizontal distance of = 17.0 before hitting the ground. From what height was the rock thrown? Use the value = 9.810 for the free-fall acceleration. PROBLEM-SOLVING STRATEGY 4.1 Projectile motion problems MODEL: Make simplifying assumptions, such as treating the object as a particle. Is it reasonable to ignore air resistance? VISUALIZE: Use a pictorial representation. Establish a coordinate system with the x axis horizontal and the y axis vertical. Show important points in the motion on a sketch. Define symbols, and identify what you are trying to find. SOLVE: The acceleration is known: and . Thus, the problem becomes one of two-dimensional kinematics. The kinematic equations are , . is the same for the horizontal and vertical components of the motion. Find from one component, and then use that value for the other component. ASSESS: Check that your result has the correct units, is reasonable, and answers the question. Model Start by making simplifying assumptions: Model the rock as a particle in free fall. You can ignore air resistance because the rock is a relatively heavy object moving relatively slowly. Visualize Part A Which diagram represents an accurate sketch of the rock’s trajectory? Hint 1. The launch angle In a projectile’s motion, the angle of the initial velocity above the horizontal is called the launch angle. ANSWER: m/s  d m g m/s2 ax = 0 ay = −g xf = xi +vixt, yf = yi +viyt− g(t 1 2 )2 vfx = vix = constant, and vfy = viy − gt t t v i Typesetting math: 100% Typesetting math: 100% Correct Part B As stated in the strategy, choose a coordinate system where the x axis is horizontal and the y axis is vertical. Note that in the strategy, the y component of the projectile’s acceleration, , is taken to be negative. This implies that the positive y axis is upward. Use the same convention for your y axis, and take the positive x axis to be to the right. Where you choose your origin doesn’t change the answer to the question, but choosing an origin can make a problem easier to solve (even if only a bit). Usually it is nice if the majority of the quantities you are given and the quantity you are trying to solve for take positive values relative to your chosen origin. Given this goal, what location for the origin of the coordinate system would make this problem easiest? ANSWER: ay At ground level below the point where the rock is launched At the point where the rock strikes the ground At the peak of the trajectory At the point where the rock is released At ground level below the peak of the trajectory Typesetting math: 100% Correct It’s best to place the origin of the coordinate system at ground level below the launching point because in this way all the points of interest (the launching point and the landing point) will have positive coordinates. (Based on your experience, you know that it’s generally easier to work with positive coordinates.) Keep in mind, however, that this is an arbitrary choice. The correct solution of the problem will not depend on the location of the origin of your coordinate system. Now, define symbols representing initial and final position, velocity, and time. Your target variable is , the initial y coordinate of the rock. Your pictorial representation should be complete now, and similar to the picture below: Solve Part C Find the height from which the rock was launched. Express your answer in meters to three significant figures. yi yi Typesetting math: 100% Hint 1. How to approach the problem The time needed to move horizontally to the final position = 17.0 is the same time needed for the rock to rise from the initial position to the peak of its trajectory and then fall to the ground. Use the information you have about motion in the horizontal direction to solve for . Knowing this time will allow you to use the equations of motion for the vertical direction to solve for . Hint 2. Find the time spent in the air How long ( ) is the rock in the air? Express your answer in seconds to three significant figures. Hint 1. Determine which equation to use Which of the equations given in the strategy and shown below is the most appropriate to calculate the time the rock spent in the air? ANSWER: Hint 2. Find the x component of the initial velocity What is the x component of the rock’s initial velocity? Express your answer in meters per second to three significant figures. ANSWER: ANSWER: t xf = d m yi t yi t t xf = xi + vixt yf = yi + viyt− g(t 1 2 )2 vfy = viy − gt vix = 7.79 m/s Typesetting math: 100% Hint 3. Find the y component of the initial velocity What is the y component of the rock’s initial velocity? Express your answer in meters per second to three significant figures. ANSWER: ANSWER: Answer Requested Assess Part D A second rock is thrown straight upward with a speed 4.500 . If this rock takes 2.181 to fall to the ground, from what height was it released? Express your answer in meters to three significant figures. Hint 1. Identify the known variables What are the values of , , , and for the second rock? Take the positive y axis to be upward and the origin to be located on the ground where the rock lands. Express your answers to four significant figures in the units shown to the right, separated by commas. ANSWER: t = 2.18 s viy = 4.50 m/s yi = 13.5 m m/s s H yf viy t a Typesetting math: 100% Answer Requested Hint 2. Determine which equation to use to find the height Which equation should you use to find ? Keep in mind that if the positive y axis is upward and the origin is located on the ground, . ANSWER: ANSWER: Answer Requested Projectile motion is made up of two independent motions: uniform motion at constant velocity in the horizontal direction and free-fall motion in the vertical direction. Because both rocks were thrown with the same initial vertical velocity, 4.500 , and fell the same vertical distance of 13.5 , they were in the air for the same amount of time. This result was expected and helps to confirm that you did the calculation in Part C correctly. ± Arrow Hits Apple An arrow is shot at an angle of above the horizontal. The arrow hits a tree a horizontal distance away, at the same height above the ground as it was shot. Use for the magnitude of the acceleration due to gravity. Part A , , , = 0,4.500,2.181,-yf viy t a 9.810 m, m/s, s, m/s2 H yi = H yf = yi + viyt− g(t 1 2 )2 vfy = viy − gt = − 2g( − ) v2f y v2i y yf yi H = 13.5 m viy = m/s m  = 45 D = 220 m g = 9.8 m/s2 Typesetting math: 100% Find , the time that the arrow spends in the air. Answer numerically in seconds, to two significant figures. Hint 1. Find the initial upward component of velocity in terms of D. Introduce the (unknown) variables and for the initial components of velocity. Then use kinematics to relate them and solve for . What is the vertical component of the initial velocity? Express your answer symbolically in terms of and . Hint 1. Find Find the horizontal component of the initial velocity. Express your answer symbolically in terms of and given symbolic quantities. ANSWER: Hint 2. Find What is the vertical component of the initial velocity? Express your answer symbolically in terms of . ANSWER: ANSWER: ta vy0 vx0 ta vy0 ta D vx0 vx0 ta vx0 = D ta vy0 vy0 vx0 vy0 = vx0 vy0 = D ta Typesetting math: 100% Hint 2. Find the time of flight in terms of the initial vertical component of velocity. From the change in the vertical component of velocity, you should be able to find in terms of and . Give your answer in terms of and . Hint 1. Find When applied to the y-component of velocity, in this problem the formula for with constant acceleration is What is , the vertical component of velocity when the arrow hits the tree? Answer symbolically in terms of only. ANSWER: ANSWER: Hint 3. Put the algebra together to find symbolically. If you have an expression for the initial vertical velocity component in terms in terms of and , and another in terms of and , you should be able to eliminate this initial component to find an expression for Express your answer symbolically in terms of given variables. ANSWER: ta vy0 g vy0 g vy(ta) v(t) −g vy(t) = vy0 − g t vy(ta ) vy0 vy(ta) = −vy0 ta = 2vy0 g ta D ta g ta ta2 t2 = a 2D g Typesetting math: 100% ANSWER: Answer Requested Suppose someone drops an apple from a vertical distance of 6.0 meters, directly above the point where the arrow hits the tree. Part B How long after the arrow was shot should the apple be dropped, in order for the arrow to pierce the apple as the arrow hits the tree? Express your answer numerically in seconds, to two significant figures. Hint 1. When should the apple be dropped The apple should be dropped at the time equal to the total time it takes the arrow to reach the tree minus the time it takes the apple to fall 6.0 meters. Hint 2. Find the time it takes for the apple to fall 6.0 meters How long does it take an apple to fall 6.0 meters? Express your answer numerically in seconds, to two significant figures. ANSWER: Answer Requested ANSWER: ta = 6.7 s tf = 1.1 s td = 5.6 s Typesetting math: 100% Answer Requested Video Tutor: Ball Fired Upward from Accelerating Cart First, launch the video below. You will be asked to use your knowledge of physics to predict the outcome of an experiment. Then, close the video window and answer the questions at right. You can watch the video again at any point. Part A Consider the video you just watched. Suppose we replace the original launcher with one that fires the ball upward at twice the speed. We make no other changes. How far behind the cart will the ball land, compared to the distance in the original experiment? Hint 1. Determine how long the ball is in the air How will doubling the initial upward speed of the ball change the time the ball spends in the air? A kinematic equation may be helpful here. The time in the air will ANSWER: be cut in half. stay the same. double. quadruple. Typesetting math: 100% Hint 2. Determine the appropriate kinematic expression Which of the following kinematic equations correctly describes the horizontal distance between the ball and the cart at the moment the ball lands? The cart’s initial horizontal velocity is , its horizontal acceleration is , and is the time elapsed between launch and impact. ANSWER: ANSWER: Correct The ball will spend twice as much time in the air ( , where is the ball’s initial upward velocity), so it will land four times farther behind the cart: (where is the cart’s horizontal acceleration). Video Tutor: Ball Fired Upward from Moving Cart First, launch the video below. You will be asked to use your knowledge of physics to predict the outcome of an experiment. Then, close the video window and answer the questions at right. You can watch the video again at any point. d v0x ax t d = v0x t d = 1 2 axv0x t2 d = v0x t+ 1 2 axt2 d = 1 2 axt2 the same distance twice as far half as far four times as far by a factor not listed above t = 2v0y/g v0y d = 1 2 axt2 ax Typesetting math: 100% Part A The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistance. Hint 1. How to approach the problem While the crate is on the plane, it shares the plane’s velocity. What is the crate’s velocity immediately after it is released? Hint 2. What affects the motion of the crate? Gravity will accelerate the crate downward. What, if anything, affects the crate’s horizontal motion? (Keep in mind that we are told to ignore air resistance, even though that’s not very realistic in this situation.) ANSWER: Correct At the moment it is released, the crate shares the plane’s horizontal velocity. In the absence of air resistance, the crate would remain directly below the plane as it fell. Score Summary: Your score on this assignment is 0%. Before the plane is directly over the target After the plane has flown over the target When the plane is directly over the target Typesetting math: 100% You received 0 out of a possible total of 0 points. Typesetting math: 100%

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