What is NEWTON'S LAW OF GRAVITATION - Concept with example.


 It states that every body in the universe attracts every other body with a force which is directly proportional to the product of their masses and is inversely proportional to the square of the distance between them.

Newton's Law of Gravitation

Vector form of Newton's law of Gravitation :


Negative sign shows that :

(i) The direction of   is opposite to that  

(ii) The gravitational force is attractive in nature

The gravitational force between two bodies are equal in magnitude and opposite in direction.





Example :

1.Two particles of masses 1 kg and 2 kg are placed at a separation of 50 cm. Assuming that the only forces acting on the particles are their mutual gravitation, find the initial acceleration of heavier particle.

Solution :

Force exerted by one particle on another

Acceleration of heavier particle

Example 2: 

Two stationary particles of masses M1 and M2 are at a distance 'd' apart. A third particle lying on the line joining the particles, experiences no resultant gravitational forces. What is the distance of this particle from M1 .

The force on m towards M1 is

The force on m towards M2 is

According to question net force on m is zero i.e. F1 = F2


Example :

Two particles of equal mass (m) each move in a circle of radius (r) under the action of their mutual gravitational attraction. Find the speed of each particle?

Solution :

For motion of particle




Post By : Preeti Rai 15 Mar, 2019 1531 views Physics