Gravity or gravitation is defined as the force of attraction acting between all matters. It is Gravitational force that keeps all the planets orbit around sun. Gravity is the force of attraction which exists between any two masses, particles or bodies. It is not only the attraction between earth and the objects.

On Earth, gravity gives weight to physical objects, and the Moon’s gravity causes the ocean tides.

## Newton’s Law of Universal Gravitation

Gravity is the force because of which the planets orbit around the sun and it keeps the moon in orbit around Earth. Newton’s law of universal gravitation states that every particle attracts every other particle in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres. The equation proposed by Newton was revolutionary. He used this equation to describe the nature of the force.

*F=Gm1m2 / r**²*

Where,** (F)** is the gravitational force, (

**and (**

*m1)***are the masses and**

*m2)***is the distance between the centre of the masses and**

*(r)***is a constant that measures the basic strength of the force called the Gravitational constant and its value is**

*(G)***6.6726 x 10**

**¯¹¹m**

**³kg**

**¯¹s**

**¯²**.