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

NEWTON'S LAW OF GRAVITATION :

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.

Vector form of Newton's law of Gravitation :

let

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 1801 views Physics