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Unformatted text preview: hernandez (ejh742) homework 29 Turner (58120) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 3) 10.0 points A weight suspended from a spring is seen to bob up and down over a distance of 24 cm twice each second. What is its frequency? Correct answer: 2 Hz. Explanation: Let : n = 2 . freq = 2 bobs 1 second = 2 Hz . 002 (part 2 of 3) 10.0 points What is its period? Correct answer: 0 . 5 s. Explanation: period = 1 freq = 1 2 Hz = . 5 s . 003 (part 3 of 3) 10.0 points What is its amplitude? Correct answer: 12 cm. Explanation: Let : d = 24 cm . The amplitude is the distance from the equilibrium position to maximum displace ment: 1 2 d = 1 2 (24 cm) = 12 cm . 004 10.0 points The oscillation of a massspring system x = x m cos( t + ) , where x m is a positive number. At time t = 0, the mass is at the equilibrium point x = 0 and it is moving with positive velocity v . What is the phase angle ? 1. = 0 2. = 5 4 3. = 3 4 4. = 5. = 2 6. = 1 4 7. = 3 2 correct 8. = 1 2 9. = 7 4 Explanation: Since the initial position is x = 0, we know that cos( ) = 0, so = 1 2 , 3 2 , 5 2 ,... . The velocity can be found as v = dx dt = x m sin( t + ) . At t = 0 we have v = x m sin( ) > 0, so the solution is = 3 2 ....
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This note was uploaded on 06/14/2011 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.
 Spring '08
 Turner
 Physics, Work

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