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Unformatted text preview: lew (dl9564) – hk6 – Opyrchal – (41104) 1 This printout should have 8 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points The angle of the inclination is θ = 44 ◦ , the outer part of the large pulley has a radius of 3 r and the inner part of the large pulley has a radius of r . The acceleration of gravity is 9 . 8 m / s 2 . Assume: All pulleys are frictionless and massless and the cords are massless. 3 r r /2 r m T θ Find the mass m needed to balance the M = 1260 kg truck on the incline shown in figure. Correct answer: 145 . 878 kg. Explanation: Let T be the tension in the string around the inner part (radius = r ) of the pulley. Then from the force equilibrium 2 T M g sin θ = 0 we obtain T = 1 2 M g sin θ = 4288 . 82 N . From the rotational equilibrium we have summationdisplay τ = 0 (sum of the torques is 0), or mg (3 r ) T r = 0 Therefore m = T 3 g = 1 6 M sin θ = 1 6 (1260 kg) sin θ = 145 . 878 kg . 002 10.0 points A uniform bar of length 16 m and mass 7 kg is attached to a wall with a hinge that exerts on the bar a horizontal force H x and a vertical force H y . The bar is held by a cord that makes a 90 ◦ angle with respect to bar and angle 37...
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This note was uploaded on 01/22/2009 for the course PHYS Phys 106 taught by Professor Opyrachal during the Fall '08 term at NJIT.
 Fall '08
 opyrachal

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