**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**

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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.