Which one of the following statements describes the condition(s) for which a rigid body is in equilibrium?

Question

Only internal forces can be present.

The sum of the externally applied forces must be zero, and the sum of the externally applied torques must be zero.

Each external force may be non-zero, but the sum of the forces must be zero.

Each external torque may not be non-zero, but the sum of the torques must be zero.

Each external torque acting on the body must be zero.

Answer 1

The sum of the externally applied forces must be zero, and the sum of the externally applied torques must be zero.

Answer 2

Each external torque may not be non-zero, but the sum of the torques must be zero