Question

Define the moment of a couple. Write its SI unit.

Answer 1

1. A couple is a pair of two equal and opposite forces acting on a body at two different points.
2. The moment of a couple is defined as the product of either of the forces of a couple and the perpendicular distance between the line of action of forces.
3. The perpendicular distance between the two forces is called the arm of the couple.
4. The S.I. unit of moment of a couple is $\mathrm{Nm}$.

Thus $Momentofcouple=eitherforce\times armofcouple$$=F\times d$