HU_Recitation # 6_Solution Sheet

# HU_Recitation # 6_Solution Sheet - HOWARD UNIVERSITY PHYS...

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HOWARD UNIVERSITY PHYS 001-RECITATON ASSIGNMENT # 6 Part I. Calculating the Amount of Work Done by Forces When a force acts to cause an object to be displaced, three quantities must be known in order to calculate the work. Those three quantities are force, displacement, and the angle between the force and displacement. Apply the work equation to determine the amount of work done by the applied force in each of the three situations described below. 1) A 100 N force is applied to move a 15 kg object a horizontal distance of 5 meters at constant speed. Solution: W = (100 N) * (5 m)* cos(0 degrees) = 500 J The force and the displacement are given in the problem statement. It is said that the force and the displacement are both rightward. Since F and d are in the same direction, the angle is 0 degrees. 2) A 100 N force is applied at an angle of 30 ° to the horizontal to move a 15 kg object at a constant speed for a horizontal distance of 5 m. Solution: W = (100 N) * (5 m) * cos(30 degrees) = 433 J It is said that the displacement is rightward. It is shown that the force is 30 degrees above the horizontal. Thus, the angle between F and d is 30 degrees. 1 | P a g e

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3) An upward force is applied to lift a 15 kg object to a height of 5 meters at constant speed. Solution: W = (147 N) * (5 m) * cos(0 degrees) = 735 J The displacement is given in the problem statement. The applied force must be 147 N since the 15-kg mass (F grav =147 N) is lifted at constant speed. Since F and
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## This note was uploaded on 11/11/2011 for the course PHYSICS 101 taught by Professor Staff during the Fall '10 term at Howard.

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HU_Recitation # 6_Solution Sheet - HOWARD UNIVERSITY PHYS...

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