Question

State the law of conservation of momentum derive the newton's second law of motion

Answer 1

law of conservation of momentum: the total momentum of an isolated system of interacting particles remains constant if there is no external force acting on it .
Newton's second law of motion: the rate of change of momentum of a body is directly proportional to the external force acting on it.

Answer 2

Newton's third law states that for a force applied by an object A on object B, object B exerts back an equal force in magnitude, but opposite in direction. This idea was used by Newton to derive the law of conservation of momentum. ... B=m_{2}(v_{2}-u_{2}) (change in momentum of particle B)