How to calculate the time for a body to fall from a height with a mass of 90 kg from a height of 30 m?

m = 90 kg.

g = 10 m / s2.

h = 30 m.

V0 = 0 m / s.

t -?

When a body falls, only the force of gravity m * g acts on it, so it moves uniformly with the acceleration of gravity g.

For uniformly accelerated motion, the path h passed by the body, in our case, the height of the fall, is expressed by the formula: h = V0 * t + g * t ^ 2/2, where V0 is the initial velocity of the body, t is the time of motion.

Since the body is falling, then its initial speed of movement is V0 = 0 m / s, the formula will take the form: h = g * t ^ 2/2.

t ^ 2 = 2 * h / g.

The body fall time t will be determined by the formula: t = √ (2 * h / g).

t = √ (2 * 30 m / 10 m / s2) = 2.45 s.

Answer: the fall of the body will last t = 2.45 s.