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.
Recommended Videos
Gravitation – Gravitational Potential Energy
Gravitation – Kepler’s Laws of Planetary Motion
Frequently Asked Questions on Properties of Gravitational Force
Explain why the tennis ball bounces higher on the hills than on the plains.
The value of ‘g’ on the hills is less than on the plains. So the weight (mg) of the tennis ball on the hills will be less than on the plains. In other words, the gravitational force with which the earth attracts the ball on the hills will be less than the plains.
The gravitational force between two bodies is 1 newton. If the distance between them is doubled, what will be the force?
F = Gm1m2/r2
If r = 2r
F’ = Gm1m2/(2r)2
F’ = F/4
Thus, the force becomes (¼) times the original force.
Earth is continuously pulling the moon towards its centre. Why does the moon not fall on the earth?
The gravitational force between the earth and the moon provides the necessary centripetal force for the moon to move around the earth. It would have fallen on the earth if the moon were at rest.
What is meant by weightlessness?
A body is said to be in a state of weightlessness if the normal reaction acting on the body placed over a freely falling frame is zero.
Comments