A drop of water comes off the roof of a 20 m high house and falls. Determine the time of the drop and the speed

A drop of water comes off the roof of a 20 m high house and falls. Determine the time of the drop and the speed that the drop will have at the moment of falling to the Earth.

These tasks: S (the path covered by the drop, the height of the house) = 20 m; free fall.
Reference values: g (acceleration due to gravity) ≈ 10 m / s2.
1) Calculate the drop fall time: S = a * t ^ 2/2, whence t = √ (2S / a) = √ (2S / g) = √ (2 * 20/10) = 2 s.
2) Determine the speed of the drop at the moment of falling: V = a * t = g * t = 10 * 2 = 20 m / s.
Check: S = V ^ 2 / 2a = V ^ 2 / 2g = 20 ^ 2 / (2 * 10) = 20 m (correct).
Answer: The drop fell from the roof of the house for 2 s and reached a speed of 20 m / s at the moment it touched the ground.