# Answer to Question #6456 in Mechanics | Relativity for Dapre

Question #6456

A tennis ball with a mass of 60 g was moving at a velocity of 3 m/s. How fast would a ball of mass 20g have to be going to have the same momentum as the tennis

Expert's answer

A tennis ball with a mass of 60 g moving at a velocity of 3 m/s has a momentum

Mt = M1*V1 = 0.06 kg * 3 m/s = 0.18 kg*m/s.

So, V2 = Mt/M2 = ( 0.18 kg*m/s ) / 0.02 kg = 9 m/s.

Mt = M1*V1 = 0.06 kg * 3 m/s = 0.18 kg*m/s.

So, V2 = Mt/M2 = ( 0.18 kg*m/s ) / 0.02 kg = 9 m/s.

## Comments

Help13.02.12, 03:41m1.v1 = m2.v2 (law of momentum)

60 . 3 = 20 . x

x = 9m/s

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