How long will it take for a stone falling from a height of 20 m without initial velocity to reach the ground?

Initial data: h (height from which the stone fell freely) = 20 m.

Reference data: according to the condition g (gravitational acceleration) = 10 m / s2.

We express the time when the stone in question reaches the ground from the formula: S = h = g * t ^ 2/2, whence t ^ 2 = 2 * h / g and t = √ (2 * h / g).

Calculation: t = √ (2 * 20/10) = √4 = 2 s.

Answer: When free falling, the stone in question will fall to the ground in 2 seconds.