Sir Issac Newton discovered the relation between the body falling freely on earth and the motion of the moon. He assumed the existence of a force of attraction between bodies, one that does not require any bodily constant. The force was called the gravitational force of attraction. He concluded that the gravitational force is needed to keep the moon go in a circular orbit around the earth.
According to “Newton’s law gravitation”, every particle in the universe attracts every other particle with a force whose magnitude is,
Directly proportional to the product of their masses i.e. F ∝ (M1M2)………..(1)
Inversely proportional to the square of the distance between their centre i.e. (F ∝ 1/r2) . . . . (2)
On combining equations (1) and (2) we get,
F ∝ M1M2/r2
10 Properties of Gravitational Force
Property 1: The gravitational force is a long-range force, which exists between two particles, regardless of the medium that separates them.
Property 2: The gravitational force is directly proportional to the product of the mass of the two bodies. This means a larger mass will yield a larger force.
Property 3: The force obeys the inverse square law. The force is inversely proportional to the square of the distance between them.
Property 4: On the surface of the earth, the gravitational force produces a constant acceleration, g = 9.8 m/s2.
Property 5: Gravitational force always acts as a force of attraction. It tries to pull masses together, it never pushes them apart.
Property 6: It is independent of the intervening medium.
Property 7: Gravitational force is the weakest of the four fundamental forces.
Property 8: It acts along the line joining the centre of the two objects. Therefore, it is called the central force.
Property 9: Gravitational force is directly proportional to the weight.
Property 10: Gravitational force acts even when the objects are not in touch.