 # Rain drops fall from a height of 1Km(approx) . v, speed just before reaching the the ground should be sq. root of 2x9.8*1000 =140 m/s. But it is not so otherwise it would have destructed so many things at this speed. Why the speed of rain is less than 140m/s.

8 years ago

this is true when we consider effect of friction zero OR we consider ideal case. In reality, wind and other obstruction in between  affects the speed of rain.

8 years ago

Because the viscosity of air is non-zero, a retarding force is experienced by the falling raindrop which is proportional to its speed.

When the upwards retarding force = downward force of gravity, the acceleration becomes zero from that time onwards and the raindrop falls with a constant velocity called the terminal velocity.

8 years ago
the raindrop faces 2 types of forces one is the upward force and the other is the downward force.when downward force equals the upward force the raindrop attains a const. velocity as there is no imbalanced force to acclerate it which is called terminal velocity.
8 years ago
because as they fall their acts two forces one mg and other air friction after a certain interval net force becomes zero and the drop gets terminal velocity.