If the sum of the external torques on an object is zero, then the sum of the external forces on it
must also be zero.

Question

Quizplus · Accepted Answer

The sum of the external torques being zero ensures angular momentum is conserved, but this does not necessarily mean the sum of the external forces is zero, as linear and angular dynamics are governed by different conditions. Zero net torque means no change in rotational motion, while zero net force means no change in linear motion; these can occur independently.

If the Sum of the External Torques on an Object