Question

derive the expression of law of conservation of angular momentum​

Answer 1

For the situation in which the net torque is zero, d→Ldt=0 d L → d t = 0 . If the change in angular momentum ΔL is zero, then the angular momentum is constant; therefore, →L=constant L → = constant (when net τ=0). This is an expression for the law of conservation of angular momentum.

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)