Write an expression for the force due to gravity on a body of mass m and explain the meaning of the symbols used in it.

The force due to gravity ‘F’ on a body of mass 'm' kept on the surface of earth of mass 'M' and radius 'R', is equal to the force of attraction between the earth and that body.

Hence, the expression is

$\text{F} = \text{G}\dfrac{\text{M}\text{m}}{\text{R}^2}$

The value of G remains same at all places and it is independent of the nature of the particles , temperature, medium, etc.

Therefore, it is a universal constant and is known as Universal Gravitational Constant.