Derive the equation for the conservation of momentum

Law of conservation of momentum is more basic than third law of motion. However here we derive the law of conservation of momentum from the third law of motion.

Let us suppose a body of mass m_{1} travelling with velocity u_{1} collides with another body of mass m_{2} and travelling with velocity u_{2.} After collision let the first body changes its velocity to v_{1} and the second body to v_{2.}

Since there is change in velocity of the either bodies there must be change in momentum and force experienced by both of them due to each other.

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