Write the Newton's second law for rotational motion about a fixed axis.

(N/A) For a rigid body rotating about a fixed axis,Newton's second law of motion is expressed in terms of torque and angular acceleration.
It states that the net external torque $\tau_{ext}$ acting on the body about the axis of rotation is equal to the product of the moment of inertia $I$ of the body about that axis and its angular acceleration $\alpha$.
The mathematical expression is: $\tau_{ext} = I \alpha$.