Question

Enplain law of conservation of momentum, Desire
its mathematical expression.​

Answer 1

Explanation:

See the above picture... and let me know if you have anymore doubt in this

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)