Vergelijking van rotatiedynamiek

Consider a point mass performing a circular motion about the center of rotation; Newton's second law of motion gives the force acting on this point mass.

The linear acceleration can be written in terms of the angular acceleration, and multiplying both sides with the radius of the circular path gives an expression for the torque.

Recalling the definition of the moment of inertia, the torque applied on a point mass can be rewritten. This is Newton's second law of rotation.

In the vector form of Newton's second law of rotation, the torque and angular acceleration are in the same direction.

This equation of rotational motion can be generalized to any rigid body rotating about a fixed axis. If multiple forces are acting on the rigid body, then the equation of rotational dynamics is expressed using the summation of all the torques.

The net torque includes only external forces, as all the internal forces cancel out due to Newton's third law of motion.