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Unformatted text preview: Bautista, Aldo Homework 2 Due: Sep 13 2005, 4:00 am Inst: Maxim Tsoi 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points The graph below shows the velocity v as a function of time t for an object moving in a straight line. t v t Q t R t S t P Which of the following graphs shows the corresponding displacement x as a function of time t for the same time interval? 1. t x t Q t R t S t P 2. t x t Q t R t S t P 3. t x t Q t R t S t P 4. t x t Q t R t S t P 5. t x t Q t R t S t P 6. None of these graphs are correct. 7. t x t Q t R t S t P 8. t x t Q t R t S t P 9. t x t Q t R t S t P correct Explanation: The displacement is the integral of the ve- locity with respect to time: ~x = Z ~v dt . Because the velocity increases linearly from zero at first, then remains constant, then de- creases linearly to zero, the displacement will increase at first proportional to time squared, then increase linearly, and then increase pro- portional to negative time squared. From these facts, we can obtain the correct answer. t x t Q t R t S t P 002 (part 1 of 4) 10 points Consider a moving object whose position x is plotted as a function of the time t on the following figure: Bautista, Aldo Homework 2 Due: Sep 13 2005, 4:00 am Inst: Maxim Tsoi 2 x 1 I 2 3 1 2 3 t O II III Clearly, the object moved in different ways during the time intervals denoted I, II and III on the figure. During these three intervals, when was the objects speed highest? Caution: Do not confuse the speed with the velocity. 1. Same speed during each of the three in- tervals. 2. During interval I. 3. During intervals II and III (same speed during those two intervals). 4. During interval III. correct 5. During interval II. Explanation: The velocity v is the slope of the x ( t ) curve; the magnitude v = | v | of this slope is the speed. Looking at the picture we see that the curve is steepest (in absolute magnitude) during the interval III and that is when the object had the highest speed. 003 (part 2 of 4) 10 points During which interval(s) did the object have no change in displacement? 1. During interval I only. correct 2. During interval II only. 3. During interval III only. 4. During intervals II and III. 5. During each of the three intervals. 6. During none of the three intervals. Explanation: The figure shows no change in displacement during the interval I but there are changes in displacements during the other intervals II and III. 004 (part 3 of 4) 10 points During which interval(s) did the objects ve- locity remain constant?...
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This note was uploaded on 10/13/2009 for the course PHY 303K taught by Professor Turner during the Fall '08 term at University of Texas at Austin.
- Fall '08