Question

ACCORDING TO CONSERVATION OF LINEAR MOMENTUM WHEN TWO OBJECTS COLLIDE THE SUM OF THEIR MOMENTUM IS SAME.

BUT,

IF I COLLIDE A BALL WITH A STONE THEN THE STONE DOES NOT MOVE. THE MOMENTUM OF THE BALL ALSO DECREASES.

WHY DOES THIS HAPPEN?

Answer 1

If the stone is very heavy the ball rebounce with the same speed but the direction of the motion is changed. So, in this case initial momentum of ball and stone system conserved i.e. initial momentum of the system is equal to the final momentum of the system.