A person drops one rock from rest and it falls 100 meters down a cliff before hitting the ground.The person then throws an identical rock downward.The amount of kinetic energy gained by the rock dropped from rest is _____ that of the second rock,and the magnitude of the change in speed (between hitting the ground and its initial speed)of the rock dropped from rest is _____ that of the second rock.
A)equal to,greater than
B)equal to,equal to
C)less than,less than
D)equal to,less than

Question

Quizplus · Accepted Answer

The kinetic energy gained by both rocks is equal because they fall the same distance under gravity. However, the change in speed is greater for the rock dropped from rest because it starts with zero initial speed, whereas the thrown rock starts with an initial downward speed.

A Person Drops One Rock from Rest and It Falls