Question

A solid ball of density half that of water falls freely under gravity from a height of 19.6 m and then enters water. Upto what depth will the ball go. How much time will it take to come again to the water surface ? Neglect air resistance and viscosity effects in water.

Answer 1

Let ρ be the density of ball and 2ρ the density of water. Net retardation inside the water,

Hence, the ball will go upto the same depth 19.6 m below the water surface.

Further, time taken by the ball to come back to water surface is ,