Question

A spherical ball of radius 3 x 10^-4 m and density 10⁴ kg/m³ falls freely under gravity through a distance h before entering a tank of water. If after entering the water the velocity of the ball does not change, find h. Viscosity of water is 9.8 x 10^-6 N-s/m².

Answer 1

Before entering the water the velocity of  ball is √2gh . If after entering the water this velocity does not change then this value should be equal to the terminal velocity. Therefore,