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Unformatted text preview: ghei (mg42382) – HW 6 – opyrchal – (11130) 1 This printout should have 8 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 2) 10.0 points Suppose the incline is frictionless for the system shown. The angle of inclination is 22 ◦ , the spring constant is 302 N / m and the mass of the block is 6 . 81 kg. The block is released from rest with the spring initially unstretched. The acceleration of gravity is 9 . 8 m / s 2 . 302 N / m 6 . 8 1 k g μ = x 22 ◦ How far x does it move down the incline before coming to rest? Correct answer: 0 . 165566 m. Explanation: Let : θ = 22 ◦ , k = 302 N / m , m = 6 . 81 kg , and μ = 0 . Energy is conserved, so U i = mg x sin θ = U f = k x 2 2 Hence, solving for x x = 2 mg sin θ k = 2 (6 . 81 kg) (9 . 8 m / s 2 ) sin 22 ◦ 302 N / m = . 165566 m . 002 (part 2 of 2) 10.0 points Choosing down the incline as the positive di rection, what is its acceleration at its lowest point? Correct answer: 3 . 67115 m / s 2 . Explanation: Only gravity and the spring force act on the block, so k x + mg sin θ = ma Therefore: a = g sin θ k x m = (9 . 8 m / s 2 ) sin22 ◦ (302 N / m)(0 . 165566 m) 6 . 81 kg = 3 . 67115 m / s 2 . 003 10.0 points A pinball machine launches a 44 g ball with a springdriven plunger. The game board is inclined at 11 ◦ above the horizontal. Assume: The plunger’s mass and frictional effects are negligible. The acceleration of gravity is 9 . 8 m / s 2 ....
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This note was uploaded on 05/02/2011 for the course PHYSICS 111 taught by Professor Wang during the Spring '09 term at NJIT.
 Spring '09
 WANG
 Physics, Friction

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