**Gravitation:**

Each object in the universe attracts every other object with a force, which is called the force of **gravitation.**

We are giving a detailed and clear sheet on all Physics Notes that are very useful to understand the Basic Physics Concepts.

## Newton’s Law of Gravitation | Definition, Formula – Gravitation

Gravitation is one of the four classes of interactions found in nature. These are

- The gravitational force
- The electromagnetic force
- The strong nuclear force (also called the hadronic force).
- The weak nuclear forces.

Gravity is the force by which earth attracts the body towards its centre.

Although, of negligible importance in the interactions of elementary particles, gravity is of primary importance in the interactions of large objects. It is gravity that holds the universe together.

**Newton’s Law of Gravitation**

Gravitational force is a attractive force between two masses m_{1} and m_{2} separated by a distance r.

The gravitational force acting between two point objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Gravitational force, F = \(\frac{G m_{1} m_{2}}{r^{2}}\)

where, G is universal gravitational constant.

The value of G is 6.67 x 10^{-11} N-m² kg^{-2} and is same throughout the universe.

The value of G is independent of the nature and size of the bodies as well as the nature of the medium between them.

Dimensional formula of G is [M^{-1}L^{3}T^{-2}].

**Note:
**Newton’s law of gravitation holds good for object lying at very large distances and also at very short distances. It fails when the distance between the objects is less than 10

^{-9}m i.e. of the order of intermolecular distances.

**Gravitational Force important points:**

- Gravitational force is a central as well as conservative force.
- It is the weakest force in nature.
- It is 10
^{36}times smaller than electrostatic force and 10^{38}times smaller than nuclear force. - The law of gravitational is applicable for all bodies, irrespective of their size, shape and position.
- Gravitational force acting between sun and planet provide it centripetal force for orbital motion.
- Newton’s third law of motion holds good for the force of gravitation. It means the gravitational forces between two bodies are action-reaction pairs.

**The following three points are important regarding the gravitational force**

1. Unlike the electrostatic force, it is independent of the medium between the particles.

2. It is conservative in nature.

3. It expresses the force between two point masses (of negligible volume). However, for external points of spherical bodies the whole mass can be assumed to be concentrated at its centre of mass.

**Gravitation:**

Have you ever thought, when we throw a ball above the ground level, why it returns back to the ground. It’s because of gravity. When a ball is thrown above the ground in the opposite direction, a gravitational force acts on it which pulls it downwards and makes it fall. This phenomena is called gravitation.

Learn relation between gravitational field and potential field, Kepler’s law of planetary, weightlessness of objects in absence of gravitation, etc.