The answer depends on the diameter and weight of the water drop ; the higher it is, the faster it falls. Even so, it is estimated that the speed ranges between 8 and 32 kilometers per hour. A raindrop can have a minimum diameter of 0.5 millimeters, like a grain of salt, and a maximum of 6.35 millimeters. In the first case, the drop falls at about 2 meters per second, that is, at 8 km / h. If the drop is large, it will go at 9 meters per second or 32 km / h. This value is obtained by means of two forces that come into play: the force of gravity and resistance to the wind.
In 1904, the physicist Philipp Lenard built a vertical wind tunnel to calculate the speed of the drops. It was then that he realized that the speed of the drop increased if it was large , but only up to a limit, 4.5 mm . If it is larger, the drop is deformed and the resistance to the wind increases, thus slowing down its fall.
