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Unformatted text preview: boland (kbb544) – HW5 – mackie – (10611) 1 This printout should have 9 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Lee pushes horizontally with a force of 52 N on a 25 kg mass for 11 m across a floor. Calculate the amount of work Lee did. Correct answer: 572 J. Explanation: Let : F = 52 N and d = 11 m . The mass of the object is ignored since there is no friction present, so W = F d = (52 N) (11 m) = 572 J . 002 10.0 points A cart loaded with bricks has a total mass of 17 . 9 kg and is pulled at constant speed by a rope. The rope is inclined at 30 . 8 ◦ above the horizontal and the cart moves 9 . 4 m on a horizontal floor. The coefficient of kinetic friction between ground and cart is 0 . 5 . The acceleration of gravity is 9 . 8 m / s 2 . How much work is done on the cart by the rope? Correct answer: 0 . 635159 kJ. Explanation: F 3 . 8 ◦ 17 . 9 kg μ = 0 . 5 Summing the components of the forces along the vertical direction provides summationdisplay F y = F sin θ + N  mg = 0 . For the horizontal direction we have summationdisplay F x = F cos θ μ k N = 0 (1) N = F cos θ μ k , so that F sin θ + F cos θ μ k mg = 0 F μ k sin θ + F cos θ = μ k mg F = μ k mg μ k sin θ + cos θ ....
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 Spring '11
 MACKIE
 Physics, Force, Friction, Mass, Correct Answer

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