Question

During a circus act, an elderly performer thrills the crowd by catching a cannon ball shot at him. The cannon ball has a mass of 10.0 kg and the horizontal component of its velocity is 8.00 m/s when the 65.0 kg performer catches it.

1. If the performer is on nearly frictionless roller skates, what is his recoil velocity?

2. How much kinetic energy is lost in this process?

Answer 1

Conservation of momentum would occur as there is net zero force acting in this instant.

So,

let m be the mass of the ball, M is mass of the man, v is the initial velocity of the ball, V is the final velocity of both man and the ball.

Here, initial velocity of the man is zero. and final velocity is same as the man catches the ball they both move together.

which is the recoiled velocity.

Kinetic Energy lost

negative sign indicates energy loss