A couple produces rotational motion.

A couple produces rotational motion.

The algebraic sum of the forces, constituting the couple is zero.

The algebraic sum of the forces, constituting the couple, about any point is the same.

A couple cannon be balanced by a single force but can be balanced only by a couple of opposite sense.

The point, through which the whole weight of the body acts, irrespective of its position, is known as centre of gravity.

The term 'centroid' is the same as centre of gravity.

The point through which the Whole mass of the body acts, irrespective of the position of the body, is known as centre of gravity (briefly written as c.g.). The plane geometrical figures (like rectangle, triangle, circle etc.) have only areas but no mass. The centre of area of such figures is known as centroid or centre of gravity of the area of the body. It may be noted that every body has one, and only one, centre of gravity.

The centre of gravity of quadrant of a circle lies along its central radius at a distance of 0.6 r.