(a) According to Newton’s law of gravitation:
(i)the force between two objects is directly proportional to the product of their masses and,
(ii)the force between two objects is inversely proportional to the square of the distance between them.

Suppose two objects of masses M₁ and M₂ are kept at a distance “d”, then the force between the two object is given as:

(b) The Newton’s law of gravitation is applicable to all types of bodies- big or small, terrestrial or celestial. So, it is called the universal law.