Question

Why does a fielder in the game of cricket pull his hands back when he catches a ball?

Answer 1

According to Newton's second law, rate of change of momentum is directly proportional to the force applied. When a fielder catches a ball, the momentum of the ball becomes zero.

Now, rate of change of momentum = $\frac{△p}{△t}$

To minimize the rate of change of momentum, $△t$ must increase, therefore by pulling his hands back, the fielder is increasing the time in which the momentum becomes zero, and thereby reducing the force exerted on his hands.