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Unformatted text preview: Morgan, Mena – Homework 14 – Due: Dec 12 2007, 11:00 pm – Inst: Opyrchal, H 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points A 19 . 9 g mass is attached to a horizontal spring with a spring constant of 6 . 48 N / m and released from rest with an amplitude of 37 . 4 cm. What is the velocity of the mass when it is halfway to the equilibrium position if the surface is frictionless? Correct answer: 5 . 84471 m / s. Explanation: Let : m = 19 . 9 g , k = 6 . 48 N / m , and A = 37 . 4 cm . x = A 2 = 0 . 187 m v = r k m ( A 2 x 2 ) = s 6 . 48 N / m . 0199 kg [(0 . 374 m) 2 (0 . 187 m) 2 ] = 5 . 84471 m / s . keywords: 002 (part 1 of 1) 10 points A car with bad shock absorbers bounces up and down with a period of 0 . 703 s after hitting a bump. The car has a mass of 1250 kg and is supported by four springs of equal force constant k . Determine a value for k . Correct answer: 24963 . 1 N / m. Explanation: Let : T = 0 . 703 s and m = 1250 kg . The spring constant is k = F x . Assuming that each spring supports an equal portion of the car’s mass; i.e. , m 4 , the angular frequency of each spring is ω = r k M = r 4 k m and the period is T = 2 π ω T = 2 π r m 4 k T 2 = 4 π 2 m 4 k k = π 2 m T 2 = π 2 (1250 kg) (0 . 703 s) 2 = 24963 . 1 N / m ....
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This note was uploaded on 04/07/2012 for the course PHYSICS 121 taught by Professor James during the Spring '12 term at University of Texas.
 Spring '12
 James
 Physics, Work

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