Free falling stone at the moment of impact on the Earth reached 40 m / s. What is the height of the fall.

Free falling stone at the moment of impact on the Earth reached 40 m / s. What is the height of the fall. How long did the stone fall?

Given:

v = 40 m / s – the speed of the stone at the moment of impact on the ground;

g = 10 m / s ^ 2 – acceleration of gravity.

It is required to determine the time of the fall of the stone t (seconds) and the height from which the stone fell H (meters).

Since at the beginning of the fall the speed of the stone was equal to zero (free fall according to the condition of the problem), we find the fall time:

t = v / g = 40/10 = 4 seconds.

Then the height from which the stone fell will be equal to:

H = a * t ^ 2/2 = 10 * 4 ^ 2/2 = 5 * 4 ^ 2 = 5 * 16 = 80 meters.

Answer: the stone fell within 4 seconds from a height of 80 meters.