Every object in the universe attracts every other object with a force which is called the force of gravitation .
Gravitation is one of the four classes of interactions found in nature . These are
( i ) the gravitational force ( ii ) the electromagnetic force ( iii ) the strong nuclear force ( also called the hadronic force ). ( iv ) the weak nuclear forces .
Although , of negligible importance in the interactions of elementary particles , gravity is of primary importance in the interactions of objects . It is gravity that holds the universe together .
Newton ’ s Law of Gravitation
Gravitational force is a attractive force between two masses m1 and m2 separated by a distance r .
The gravitational force acting between two point objects is proportional to the product of their masses and inversely proportional to the square of the distance between them .
Gravitational force .
where G is universal gravitational constant .
The value of G is 6.67 X 10 -11 Nm 2 kg -2 and is same throughout the universe .
The value of G is independent of the nature and size of the bodies well as the nature of the medium between them .
Dimensional formula of Gis [ M -1 L 3 T -2 ].