Question

give 2 examples of illustrating the law of conservation of momentum

Answer 1

recoil of gun and collision of two persons

Answer 2

As I said before to give something acceleration we must apply an external force. If there is no force then object continue its motion. For momentum change we must apply impulse, in other words there must be external applied force to change momentum of the object. If there is no force applied then momentum of the system is conserved in magnitude and direction.

Pinitial=Pfinal