We know, the amount of force by which an object is attracted towards the centre of the earth is called its weight. A body kept in any way its weight always acts on the body through a point. This point is called centre of gravity or centre of weight.
The point through which its weight acts is called its centre of gravity. It is a point from which the weight of a body or system may be considered to act. In uniform gravity, it is the same as the centre of mass. Sometimes it is called centre of weight.
Explanation: Let A be a rigid body. It is composed of many small particles. Each particle will be attracted by the gravitational force towards the centre of the earth combination of these forces creates the resultant force. Now whatever way the body is kept the magnitude, direction and point of action of the force of attraction of the earth or the particles will not change and also the magnitude, direction and point of action of the resultant of those forces will not change. This resultant force is the weight of the body. The centre of gravity of an object is the point at which weight is evenly dispersed and all sides are in balance. A human’s centre of gravity can change as he takes on different positions, but in many other objects, it’s a fixed location. In the figure, the weight of the body is acting through the point G. This point is the centre of gravity of the body.