When you drop a pebble from height H, it reaches the ground with kinetic energy K if there is no air resistance. From what height should you drop it so it will reach the ground with twice as much kinetic energy?
A) $\sqrt { 2 }$ H
B)2H
C)4H
D)8H
E)16H

Question

Quizplus · Accepted Answer

The kinetic energy of the pebble when it reaches the ground is proportional to the height from which it is dropped. To achieve twice the kinetic energy, the pebble must be dropped from twice the original height, hence 2H.

When You Drop a Pebble from Height H, It Reaches 2\sqrt { 2 }2​

When You Drop a Pebble from Height H, It Reaches $\sqrt { 2 }$