From what height did the body fall if it hit the ground at a speed of 30m / s.

Given:

v = 30 meters per second – the speed of the body near the ground at the moment of its fall from a certain height;

g = 10 meters per second squared – the acceleration of gravity.

It is required to determine h (meter) – from what height the body should fall.

Since the condition of the problem is not said, we assume that there is no air resistance.

Then, based on the law of conservation of energy:

Ekinetic (near the Earth) = Epotential (at height h);

m * v ^ 2/2 = m * g * h, where m is body weight;

v ^ 2/2 = g * h;

h = v ^ 2 / (2 * g) = 30 ^ 2 / (2 * 10) = 900/20 = 90/2 = 45 meters.

Answer: the body fell from a height of 45 meters.