A ball of mass 200 g falls from a height of 5 m. What will be its kinetic energy when it just reaches the ground? (g = 9.8 m s-2)
m = 200 g.
h = 5 m.
When the ball reaches the ground then P.E. = K.E.
K.E. = mgh = 200/1000 x 9.8 x 5 = 9.8 Joule