#3.2.3a
moment of force
#3.2.3b
couple; torque of a couple
#3.2.3c
the principle of moments
#3.2.3d
centre of mass; centre of gravity; experimental determination of centre of gravity
#3.2.3e
equilibrium of an object under the action of forces and torques
#3.2.3f
condition for equilibrium of three coplanar forces; triangle of forces.