A ball of mass 200 g falls from a height of 5 metres. What is its kinetic energy when it just reaches the ground? (g = 9.8 m/s2)
Mass of the ball, m = 200g = 0.2Kg
Height from which ball is dropped, h = 5m
Initial velocity of the ball, (u) = 0m/s
Acceleration due to gravity, (g) = 9.8m/s2
Therefore, final velocity (v) of the ball is:
V2 = u2 + 2as
By substituting the above given values, we get
V2 = 0 + 2(9.8) (5)
V2 = 98
As we know, kinetic energy,
K.E = 1/2mv2
K.E = 1/2 x 0.2 x 98
K.E = 9.8 J
Hence, the kinetic energy = 9.8 J