Question

A stone drops down a well takes 2 seconds to reach the water surface.calculate velocity with which to hits the water

Answer 1

Explanation:

I take it that dropped means no initial velocity ergo s=0.5*g*t^2, where s is distance traveled, g is acceleration due to gravity(9.81 or 10) and t is the time. So it comes to around 19.62 meters.

Now the speed is (again taking initial velocity to be 0) v=g*t, therefore velocity is around 19.62 meter per second.

now if there was drag due to air, the time taken would be more, and the stone would not reach such a velocity(it will reach the terminal velocity which is lower and then remain a constant)