Which of the following options correctly describes the necessary conditions for a rigid body to be in mechanical equilibrium?
The net external force acting on the body is zero, and it must be at rest.
The net external torque (turning effect) acting on the body about any axis is zero.
Both the net external force and the net external torque acting on the body must be zero.
There are absolutely no internal or external forces acting on the body.
43 exam-style questions on CIE IGCSE Physics 1.5.2a Moment of a force. Each one has a worked solution and a mark scheme showing where the marks go.