A 700-N man jumps out of a window into a fire net 10 m below.The net stretches 2 m before bringing the man to rest and tossing him back into the air.The maximum potential energy of the net, compared to its unstretched potential energy, is:
A)300 J
B)710 J
C)850 J
D)7000 J
E)8400 J

Question

Quizplus · Accepted Answer

The gravitational potential energy lost by the man is converted into the elastic potential energy of the net. The man falls 10 m, so the gravitational potential energy lost is mgh = 700 N * 10 m = 7000 J. The net stretches 2 m, so the maximum potential energy of the net is 7000 J + (700 N * 2 m) = 8400 J.

A 700-N Man Jumps Out of a Window into a Fire