## Thursday, March 17, 2016

### Gravitational Force of Attraction and Newton's Law

Gravitational force is the weakest force among all the forces in nature. There are three basic forces in nature. They are gravitational force, electromagnetic force and nuclear force. Gravitational force exists between every two bodies as all the bodies have large or small mass. Gravitational force between any two bodies depends on the mass of the bodies and distance of separation between the bodies.

Electromagnetic force exists between every two charges and if charges are similar, it is attractive and if the charges are opposite, force between the two charges is attractive. But gravitational force is always attractive force and never repulsive.

Gravitational force is independent of the medium between the two bodies. It means the gravitational force of attraction between the bodies remains same even if the medium is changed.

Presence of a third body is not going to change the gravitational force between the given two bodies. Because of the new body, the total gravitational force on a given body will increase but the force between the two bodies remains same. If there are number of bodies, to find the effective gravitational force on a given body, we need to use law of superimposition and vector law of addition.

Gravitational force is a long range force and exists between every two objects of the universe. Gravitational force is the basic force applied by the sun on the earth planet so that it is acting like a centripetal force and the earth is revolving around the sun.

Nuclear force acts between the nucleons with in the nucleus. It exists between proton-proton and proton-neutron. Nuclear force is independent of charge of nucleons and it is a very short range force. It is the strongest force of the nature but acts with in the nucleus. Thus we can find the perfect balance in the nature. All basic forces are helping the universe to be intact.

We can find the magnitude of the gravitational force between any two bodies using Newton’s law of gravitation. According to this law, the force of attraction between the two bodies is directly proportional to the product of the mass of the two bodies and inversely proportional to the square of the distance of separation. The proportional constant of the formula depends on the nature and it is constant over the entire universe. Gravitational force is independent of the medium between the two bodies.

The presence of a new mass between any two bodies won’t affect the gravitational force them. If we need to find the total force acting on a body due to multiple bodies around it, we need to use vector laws of addition and find the effective force acting on the body.

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