The centre of gravity of a body is the point at which the force of gravity can be considered to act on a body. The centre of mass does not have to be inside the body.
We can find the centre of mas of a body by suspending the body from two or more points separately. Each time the centre of mass will lie on the vertical drawn down from the suspension point.
The intersection of the lines is the centre of mass.
Closely related to the centre of gravity is the centre of mass. The centre of mass is moree of a geometrical concept than the centre of gravity, derived from forces. The difference is only important when the gravitational field is strong and non uniform. In this case the centre of mass will be at the same position inside the body, but the centre of gravity will be shifted in the direction of the force.
