5.6 Newton's Second Law in Rotational Form

Newton's Second Law in Rotational Form

Newton’s 1st law in rotational form introduces the idea of rotational equilibrium. When the net torque acting on a rigid body is 0, the rigid body is in a state of rotational equilibrium, where its angular velocity will not change. This can be modeled with the equation ${\tau_{net}=0}$. With this logic, in order to change angular velocity, a nonzero net external torque needs to be exerted on the rigid body.

It is important to note that rotational equilibrium and translational equilibrium are independent of each other. For example, an object’s center of mass can be accelerating linearly but still have a constant angular velocity. In order to fully solve a problem, sometimes you may need to examine both the translational and the rotational motions of an object.