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Unformatted text preview: Version 068/ABABA Test1 Tsoi (58020) 1 This printout should have 16 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A certain force with units of measure M L T 2 is given by the equation F = K M L 2 T 4 , where M is a mass, L is a length, T is a time and K is a constant. What are units of the constant K ? 1. [ K ] = M 2 L 2 T 6 2. [ K ] = T 6 M 2 L 2 3. [ K ] = T 2 M L 4. [ K ] = T 2 L correct 5. [ K ] = L T 2 6. [ K ] = M L T 2 Explanation: Solving for K , K = F T 4 M L 2 Since the dimensions of force are [ F ] = M L T 2 , we get [ K ] = parenleftbigg M L T 2 parenrightbigg T 4 M L 2 = T 2 L 002 10.0 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 is correct. 7. t x t Q t R t S t P 8. t x t Q t R t S t P correct Version 068/ABABA Test1 Tsoi (58020) 2 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 . 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 003 10.0 points The acceleration due to gravity on planet X is one fifth that on the surface of the earth. If it takes 4 . 3 s for an object to fall a certain distance from rest on earth, how long would it take to fall the same distance on planet X? 1. 7.82624 2. 8.94427 3. 8.27345 4. 9.61509 5. 7.60263 6. 6.93181 7. 10.7331 8. 10.5095 9. 9.39149 10. 9.8387 Correct answer: 9 . 61509 s. Explanation: Because the acceleration due to gravity is uniform near the surface of both planets, the distance an object falls in a time t is given by x fall = g planet t 2 2 where g planet is the force of gravity near the surface of the given planet. Since the distance x fall is the same for both planets, then x fall = g e t 2 e 2 = g x t 2 x 2 = 1 5 g e t 2 x 2 t 2 e = 1 5 t 2 x t x = 5 t e = 5(4 . 3 s) = 9 . 61509 s . 004 10.0 points Identify all of those graphs that represent mo tion at constant speed (note the axes care fully). a) t x b) t v c) t a d) t v e) t a Version 068/ABABA Test1 Tsoi (58020) 3 1. (a) and (c) 2. (d) only 3. (a) only 4. (a) and (d) correct 5. (c) only 6. None of these 7. (a), (b), and (e) 8. (a), (b), and (c) 9. (a), (b), and (d) 10. (e) only Explanation: v = v o and a = 0 ....
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This note was uploaded on 09/01/2009 for the course PHY M taught by Professor Staff during the Spring '09 term at University of Texas at Austin.
 Spring '09
 Staff
 Physics, Force

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