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Unformatted text preview: lavallo (jhl936) Homework 13 florin (58140) 1 This printout should have 10 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points The speed of a moving bullet can be deter mined by allowing the bullet to pass through two rotating paper disks mounted a distance 68 cm apart on the same axle. From the angular displacement 37 . 9 of the two bul let holes in the disks and the rotational speed 1263 rev / min of the disks, we can determine the speed of the bullet. 37 . 9 v 1263 rev / min 68 cm What is the speed of the bullet? Correct answer: 135 . 964 m / s. Explanation: Let : = 1263 rev / min , d = 68 cm , and = 37 . 9 . = t t = , so the speed of the bullet is v = d t = d = (68 cm) (1263 rev / min) 37 . 9 360 1 rev 1 m 100 cm 1 min 60 s = 135 . 964 m / s . keywords: 002 10.0 points A bug is on the rim of a 78 rev / min, 12 in . diameter record. The record moves from rest to its final angular speed in 3 . 22 s. Find the bugs centripetal acceleration 1 . 5 s after the bug starts from rest. (1 in = 2.54 cm). Correct answer: 2 . 20649 m / s 2 . Explanation: Let : w = 78 rev / min , t = 3 . 22 s , r = 6 in , and t = 1 . 5 s . = t , so = t = t t = 78 rev / min 3 . 22 s (1 . 5 s) 1 min 60 s = 3 . 80504 rad / s , and a r = v 2 t r = r 2 = (6 in)(3 . 80504 rad / s) 2 1 cm 2 . 54 in 1 m 100 cm = 2 . 20649 m / s 2 . 003 10.0 points A small wheel of radius 2 . 2 cm drives a large wheel of radius 14 . 3 cm by having their cir cumferences pressed together....
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 Spring '10
 Florin

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