CENTRE OF GRAVITY
CENTRE OF GRAVITY:
It is defined as the point at which the whole weight of the body is assumed to be concentrated. Considering the body and the Earth, the body may be assumed to be made up of numerous masses which are attracted towards the earth and forces of attraction between these masses and the earth may be assumed to be parallel because of huge size of the earth. It is then possible to find out a single resultant of these forces and its point of application on the body may be found out by composition of forces. This point of application on resultant gravitational force on a body is called centre of gravity.
IMPORTANT POINTS REGARDING CENTRE OF GRAVITY:
- A body is always having only one C.G.
- The C.G. of a body is independent of the position of the body i.e., the C.G. of a body does not change if its position is changed.
- The C.G. of a body depends upon the shape of the body.
- The C.G. of a body is an imaginary point which may or may not lie within the body.
The plane figures (like triangle, quadrilateral, circle, square etc.) have only areas, but no mass. The
centre of area of such figures is known as centroid. The method of finding out the centroid of a figure is the same as that of finding out the centre of gravity of a body.
DIFFERENCE BETWEEN C.G. AND CENTROID:
|CENTRE OF GRAVITY||CENTROID|
|It is the point through which weight of a body acts.||It is the point through which whole area of the lamina is supposed to act.|
|CG is used for bodies which have mass.||Centroid is used for bodies which does not have mass.|