PHY303K HW1 - perez (nap563) HW01 Tsoi (58160) 1 This...

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Unformatted text preview: perez (nap563) HW01 Tsoi (58160) 1 This print-out should have 24 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A mass attached to a spring oscillates back and forth as indicated in the position vs. time plot below. P x t At point P, the mass has 1. positive velocity and negative accelera- tion. correct 2. positive velocity and positive accelera- tion. 3. negative velocity and negative accelera- tion. 4. negative velocity and positive accelera- tion. 5. zero velocity and zero acceleration. 6. negative velocity and zero acceleration. 7. zero velocity but is accelerating (posi- tively or negatively). 8. positive velocity and zero acceleration. Explanation: The velocity is positive because the slope of the curve at P is positive. The acceleration is negative because the curve is concave down at P. 002 10.0 points Consider three position curves between time points t A and t B . s B s A B A t A t B 3 2 1 t s Choose the correct relationship among quantities v 1 , v 2 , and v 3 . v = v A + v B 2 when a is a constant. 1. v 1 > v 2 > v 3 2. v 1 < v 2 < v 3 3. v 1 = v 2 = v 3 correct Explanation: The average velocity of an object is v = displacement time = s B- s A t B- t A . All three curves have exactly the same change in position s = s B- s A in exactly the same time interval t = t B- t A , so all three average velocities are equal: v 1 = v 2 = v 3 . 003 (part 1 of 2) 10.0 points Consider the position-time graph for a squir- rel running along a clothesline. b b b b b b 1 2 3 4 5 1 2 3 4- 1- 2 time (s) position(m) What is the squirrels displacement at the time t = 4 . 0 s? Your answer must be within 5.0% Correct answer:- 1 m. Explanation: perez (nap563) HW01 Tsoi (58160) 2 Let : x f =- 1 m and x i = 0 m . The displacement is x = x f- x i = (- 1 m)- (0 m) =- 1 m . 004 (part 2 of 2) 10.0 points What is the squirrels average velocity during the time interval between 0.0 s and 4.0 s? Your answer must be within 5.0% Correct answer:- . 25 m / s. Explanation: Let : t = 4 . 0 s . v avg = x t =- 1 m 4 s =- . 25 m / s . 005 10.0 points The graph 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 graph shows the corresponding dis- placement x as a function of time t for the same time interval? 1. t x t Q t R t S t P 2. None of these graphs is correct. 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. t x t Q t R t S t P 7. t x t Q t R t S t P correct 8. t x t Q t R t S t P 9. t x t Q t R t S t P Explanation: The displacement is the integral of the ve- locity with respect to time: vectorx = integraldisplay vectorv dt....
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This note was uploaded on 03/17/2010 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.

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PHY303K HW1 - perez (nap563) HW01 Tsoi (58160) 1 This...

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