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Unformatted text preview: lim (kl9356) Homework 13 Weathers (17104) 1 This printout should have 13 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 66 cm apart on the same axle. From the angular displacement 33 . 7 of the two bul let holes in the disks and the rotational speed 1320 rev / min of the disks, we can determine the speed of the bullet. 33 . 7 v 1320 rev / min 66 cm What is the speed of the bullet? Correct answer: 155 . 11 m / s. Explanation: Let : = 1320 rev / min , d = 66 cm , and = 33 . 7 . = t t = , so the speed of the bullet is v = d t = d = (66 cm) (1320 rev / min) 33 . 7 360 1 rev 1 m 100 cm 1 min 60 s = 155 . 11 m / s . keywords: 002 10.0 points A wheel starts from rest at t = 0 and rotates with a constant angular acceleration about a fixed axis. It completes the first revolution in 6 . 2 s. How long after t = 0 will the wheel com plete the second revolution? Correct answer: 8 . 76812 s. Explanation: Let : t 1 = 6 . 2 s , 1 = 1 rev , and 2 = 2 rev . The wheel starts from rest, so = + 1 2 t 2 = 1 2 t 2 t 2 . Thus 2 1 = t 2 2 t 2 1 t 2 = radicalbigg 2 1 t 1 = radicalbigg 2 rev 1 rev (6 . 2 s) = 8 . 76812 s . 003 10.0 points A bicycle is turned upside down while its owner repairs a flat tire. A friend spins the other wheel of radius 0 . 4 m and observes that drops of water fly off tangentially. She mea sures the height reached by drops moving ver tically. A drop that breaks loose from the tire on one turn rises 24 cm above the tangent point. A drop that breaks loose on the next turn rises 19 . 7 cm above the tangent point (the angular speed of the wheel is decreas ing). lim (kl9356) Homework 13 Weathers (17104) 2 h . 4 m radius Find the angular deceleration of the wheel. The acceleration of gravity is 9 . 8 m / s 2 . As sume the angular deceleration is constant....
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This note was uploaded on 09/07/2010 for the course PHYS 1710 taught by Professor Weathers during the Fall '08 term at North Texas.
 Fall '08
 Weathers
 Magnetism, Work

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