A kid slides down an icy (frictionless) hill starting from rest. At the top his gravitational potential energy is 500 J. Suppose after reaching the bottom he then continues sliding up another icy slope on the other side of the valley. When he finally comes to a stop he will have reached a height

Question

Quizplus · Accepted Answer

Since there is no friction, the total mechanical energy of the kid (kinetic plus potential) is conserved. Thus, at the bottom of the first hill, all of the potential energy has been converted to kinetic energy. This kinetic energy will then carry the kid up the second hill until it is all converted back to potential energy at the top. Since the total mechanical energy has been conserved, the kid must reach the same height on the other side of the valley as he started from on the first hill.

A Kid Slides Down an Icy (Frictionless) Hill Starting from Rest