When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed should you throw it up vertically so it will go twice as high?
A) 16V
B) 8V
C) 4V
D) 2V
E) $\sqrt { 2 }$ V

Question

Quizplus · Accepted Answer

The maximum height reached by a projectile is proportional to the square of its initial velocity. To reach twice the height, the initial speed must be multiplied by the square root of 2.

When You Throw a Pebble Straight Up with Initial Speed 2\sqrt { 2 }2​

When You Throw a Pebble Straight Up with Initial Speed $\sqrt { 2 }$