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While leaning out a window that is 6.6 m above the ground, you drop a 0.60-kg ba

ID: 1445176 • Letter: W

Question

While leaning out a window that is 6.6 m above the ground, you drop a 0.60-kg basketball to a friend at ground level. Your friend catches the ball at a height of 1.7 m above the ground. Determine the following.

(a) the amount of work done by the force of gravity on the ball     ___J

(b) the gravitational potential energy of the ball-earth system, relative to the ground when it is released _____J

(c) the gravitational potential energy of the ball-earth system, relative to the ground when it is caught ____J

(d) the ratio of the change (PEf PE0) in the gravitational potential energy of the ball-earth system to the work done on the ball by the force of gravity

PE / W=

Explanation / Answer

(a)

workdone by force of gravity is W = mg(h1 - h2) = (0.6)(9.8)(6.6-1.7) = 28.8 J

(b)

the gravitational potential energy of the ball-earth system, relative to the ground when it is releasedis,

            PE1= mgh1 = (0.6)(9.8)(6.6) = 38.8 J

the gravitational potential energy of the ball-earth system, relative to the ground when it is catched is,

            PE2= mgh2 = (0.6)(9.8)(1.7) = 10.0 J

the ratio of the change (PEf PE0) in the gravitational potential energy of the ball-earth system to the work done on the ball by the force of gravity is

PE2 -PE1 / W = 1.0

(c) the gravitational potential energy of the ball-earth system, relative to the ground when it is catched is, PE2= mgh2 = (0.6)(9.8)(1.7) = 10.0 J

(d)the ratio of the change (PEf PE0) in the gravitational potential energy of the ball-earth system to the work done on the ball by the force of gravity is PE2 -PE1 / W = 1.0