Answer to Question #108068 in Mechanics | Relativity for Valentine Agun

Question

If you see an object rotating, is there necessarily a net torque acting on it?

Answer 1

If the object is rotating at constant angular velocity, then the net torque is zero. That means the applied torque is exactly equal to the frictional torque. If the angular velocity is not constant, the net torque is not zero but will be equal to the product of the angular acceleration and the moment of inertia.