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Unformatted text preview: royal (sbr438) Chapter 11 Carter (32452) 1 This printout should have 17 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 2) 10.0 points Zak, helping his mother rearrange the furni ture in their living room, moves a 48 . 7 kg sofa 4 . 3 m with a constant force of 20 N. What is the work done by Zak on the sofa? Neglect friction. Correct answer: 86 J. Explanation: Let : F = 20 N and d = 4 . 3 m . W = F d = (20 N) (4 . 3 m) = 86 J . 002 (part 2 of 2) 10.0 points What is the average acceleration of the sofa? Correct answer: 0 . 410678 m / s 2 . Explanation: Let : F = 20 N and m = 48 . 7 kg . F = ma a = F m = 20 N 48 . 7 kg = . 410678 m / s 2 . 003 (part 1 of 4) 10.0 points You throw a softball (of mass 200 g) straight up into the air. It reaches a maximum altitude of 13 . 9 m and then returns to you. What is the gravitational potential energy of the softball at its highest position? Assume the ball departed from and returned to ground level. Correct answer: 27 . 244 J. Explanation: Let : m = 200 g = 0 . 2 kg , g = 9 . 8 m / s 2 , and h = 13 . 9 m . U top = mg h = (0 . 2 kg) (9 . 8 m / s 2 ) (13 . 9 m) = 27 . 244 J . 004 (part 2 of 4) 10.0 points Assume no energy is lost by the softball while it is in the air. What is the kinetic energy of the softball as soon as it leaves your hand? Correct answer: 27 . 244 J. Explanation: By the law of conservation of energy, K + U = const . The kinetic energy at the softballs highest position is 0, and the po tential energy when it leaves your hand is 0, so K bottom = U top = 27 . 244 J . 005 (part 3 of 4) 10.0 points What is the kinetic energy of the softball when it returns to your hand?...
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 Spring '11
 carter
 Physics

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