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Unformatted text preview: alexander (jra2623) homework 27 Turner (92510) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A 130 N object vibrates with a period of 3.12 s when hanging from a spring. What is the spring constant of the spring? The acceleration of gravity is 9 . 81 m / s 2 . Correct answer: 53 . 7434 N / m. Explanation: Let : F g = 130 N , T = 3 . 12 s , and g = 9 . 81 m / s 2 . T = 2 radicalbigg m k parenleftbigg T 2 parenrightbigg 2 = m k k = m parenleftbigg 2 T parenrightbigg 2 = F g g parenleftbigg 2 T parenrightbigg 2 = 130 N 9 . 81 m / s 2 parenleftbigg 2 3 . 12 s parenrightbigg 2 = 53 . 7434 N / m . 002 10.0 points When an object oscillating in simple harmonic motion is at its maximum displacement from the equilibrium position, which of the follow ing is true of the values of its speed and the magnitude of the restoring force? Magnitude of Speed Restoring Force 1. 1 2 maximum 1 2 maximum 2. Zero Zero 3. Maximum Zero 4. Maximum 1 2 maximum 5. Zero Maximum correct Explanation: The maximum displacement occurs at the turning points (where the velocity or speed is zero). The magnitude of restoring force is given by Hookes law F = k x , where k is the spring constant and x is the displacement. Since x is a maximum, F is a maximum. From a different perspective, the displace ment from the equilibrium position can be written as y = A sin , where is the phase of the oscillation. When the object is at its maximum displacement sin = 1 = 2 so its speed is...
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 Summer '08
 Kaplunovsky
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