Theory:

The centre of gravity of an object is the point through which the entire weight of the object appears to act.
Let us understand this with an example,
 
Try to balance a scale on your fingertip. What do we observe? We can see that there is only one point on which the scale is balanced. The point at which the scale is balanced is called the centre of gravity of the scale.
 
Centre of gravity on a regular - shapes objects:  
Generally, the center of gravity of the geometrically shaped object lies in the geometric center of the object.
In the below figures, you can see where the centre of gravity lies on regular shaped objects.
 
post card1.JPG
Rectangular shaped objects
 
Ring1.JPG
Ring
 
Thus, in this section, we learned that,
  • The centre of gravity of an object is the point where the entire weight of the object appears to act.
  • The centre of gravity of the geometrically shaped object lies in the geometric centre of the object.