Let us summarize this lecture by summarizing what we have learnt:

(1) For equilibrium of a body

are necessary and sufficient conditions.

(2) The torque about a point due to forces applied on a body, is an origin dependent quantity but for special case of it is origin independent.

(3) A particular case of is a couple moment when two forces are equal & opposite and are separated by distance d . The couple moment is .

(4) Torque about an axis is given by it component along the axis. Thus y and axis is along direction.

(5)