hw 20 sol

# hw 20 sol - Patel (pnp223) homework 20 Turner (92160) 1...

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Unformatted text preview: Patel (pnp223) homework 20 Turner (92160) 1 This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 3) 10.0 points A 12000 kg tank moving at 7 m / s is brought to a halt in 2 . 5 s by a reinforced-steel tank barrier. What impulse was imparted to the tank? Correct answer: 84000 kg m / s. Explanation: Let : m = 12000 kg and v = 7 m / s . I = m v = (12000 kg) (7 m / s) = 84000 kg m / s . 002 (part 2 of 3) 10.0 points What is the average net force exerted by the tank on the barrier? Correct answer: 33600 N. Explanation: Let : t = 2 . 5 s . I = F t F = I t = 84000 kg m / s 2 . 5 s = 33600 N . 003 (part 3 of 3) 10.0 points What is more important in determining the amount of damage an object sustains in a collision? 1. the total momentum change per unit time correct 2. None of these 3. the total momentum change 4. Both of these Explanation: The force (change in momentum per unit time) determines the damage. To decrease the force the time must increase, and vice versa. 004 (part 1 of 2) 10.0 points A 1 kg steel ball and 7 m cord of negligi- ble mass make up a simple pendulum that can pivot without friction about the point O . This pendulum is released from rest in a hor- izontal position and when the ball is at its lowest point it strikes a 1 kg block sitting at rest on a shelf. Assume that the collision is perfectly elastic and take the coefficient of friction between the block and shelf to be 0 . 03....
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## This note was uploaded on 07/11/2009 for the course PHY 92160 taught by Professor Turner during the Spring '09 term at University of Texas.

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hw 20 sol - Patel (pnp223) homework 20 Turner (92160) 1...

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