The diagram shows two forces F1 = 5 N and F2 = 3 N acting at points A and B of a rod pivoted at a point O, such that OA = 2 m and OB = 4 m

Calculate:
(i) the moment of force F1 about O.
(ii) the moment of force F2 about O.
(iii) total moment of the two forces about O.

OA = 2m

OB = 4m

F1 = 5N

F2 = 3N

As we know,

Moment of force = F × r

Substituting the values of F and r

(i) Moment of force F1 about O = 5 × 2 = 10 N m

(ii) Moment of force F2 about O = 3 × 4 = 12 N m

(iii) Total moment of two forces about midpoint is = 12 N m – 10 N m = 2 N m

Therefore, total moment of two forces about O is 2Nm (clockwise)