Centre of gravity – The centre of gravity of a body is a point about which the algebraic sum of moments of all the particles constituting the body is zero.
| *Note –
(i) the position of the centre of gravity of a body of given mass depends on its shape.
(ii) It is not necessary that the centre of gravity always be within the material of the body.
Centre of gravity of some regular uniform objects
Object Position of centre of gravity
1. Rod Mid-point of the rod.
2. Circular disc Geometric centre.
3. Solid or hollow sphere The geometric centre of the sphere.
4. Solid or hollow cylinder Mid-point on the axis of the cylinder.
5. Solid cone At a height h/4 from its base.
6. Hollow cone At a height of h/3 from its base.
7. Circular ring Centre of the ring
8. Triangular lamina of a scalene triangle The point of intersection of medians.
9. Parallelogram The point of intersection of the diagonal.