# A tennis player places a 58 kg ball machine on a frictionless surface, as shown below. The...

## Question:

A tennis player places a 58 kg ball machine on a frictionless surface, as shown below. The machine fires a 0.068 kg tennis ball horizontally with a velocity of 31.6 m/s toward the north. What is the final velocity of the machine? ..............m/s to the south

## Conservation of momentum

According to the Law of the conservation of the momentum, if there is no external force available in the system then the change in the momentum of the system would be zero.

Given

Mass of the machine (M) = 58 kg

Mass of the ball (m) = 0.068 kg

Velocity of the ball (v) = 31.6 m/s

Velocity of the machine = V

Now, from the conservation of the momentum, we can write

{eq}mv + MV = 0 (0.068*31.6) + (58V) = 0 \\ V = - 0.037 \ m/s {/eq}

-ve sign shows that the direction of the motion would be toward south.