Question

On the Moon, where air resistance is negligible, an astronaut drops a rock from a cliff and notes that the rock has a speed v after falling from its point of release for a time t. Assuming that the rock does not hit the ground first, how fast will it be moving after it has fallen for a time 4t from its point of release?

Answer 1

Answer:

4v

Explanation:

If the rock has a speed v after falling from its point of release for a time t, we can calculate the gravitational acceleration on the moon:

$v = g_mt$

$g_m = v/t$

So after a time of 4t, its speed would be

$v_{4t} = g_m4t = \frac{v}{t}4t = 4v$