Does conservation of angular momentum is only applicable about centre of mass axis?Or we conserve it about any axis?Please please clear my doubt.This is a question. I got this answer but can anyone please solve it by taking centre of disc as axis.

A circular disc of mass m and radius R rests flat on a horizontal frictionless surface.A bullet,also of mass m and moving with a velocity v,strikes the disc and gets embedded in it.The angular velocity with which the syatem rotates after the bullet strikes the hoop is:-Ans(v/2R)

Three identical balls are placed on a frictionless horizontal surface touching each other. They stick to each other because of adhesive. Another ball of same radius and mass m is placed over the void created by the three balls. Find the forces applied by the balls kept on the floor to each other if the system remains in equilibrium.

A car loaded with water having total mass 1000 kg moves on a straight horizontal Road starting from rest under the action of a force of 100 Newton. The water spills throw a small hole in the bottom at a rate of 0.1 KG per second the velocity of cart after 300 seconds is nearly.

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