I am fond of watching cricket and used to see that when cricket player have to catch a ball he lower his hands. But why ?
To understand this concept, first you have to know about Momentum and Impulse.
MOMENTUM:
The amount of the motion contained in a body is defined as momentum. It is given by the product of mass and velocity. It is denoted by p and is a vector quantity.
IMPULSE:
It quantifies the overall effect of force acting over time. It is conventionally given the symbol J and its unit is Newton-seconds.
Impulse is also defined as change in momentum of a body.
The formula for impulse is,
J = F.t = p2 - p1
Now, while catching a ball, a cricket player lower his hands to save himself from getting hurt. By lowering his hands, he increases the time interval in which the catch is completed. So, rate of change of momentum of the ball decreases due to which lower force acts on the hands of the player and he saves himself from getting hurt.