Question

State the Newton's law of gravitation.

Answer 1

Newton in 1687 proposed force law that we call Newton’s law of gravitation. According to him, “every particle of matter in the universe attracts every other particle with a gravitational force whose magnitude is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them”. Thus

Here, m₁ and m₂ are the masses of the particles, r is the distance between them and G is the gravitational constant, with a value that is now known to be 

G = 6.67 × 10^–11 N–m² /kg² 

G = 6.67 × 10^–11 m³ /kg–s² 

The direction of the force F is along the line joining the two particles. Regarding gravitational force, following points should be noted : 

1. The gravitational force between two particles is independent of the presence of other bodies or the properties of the intervening medium. 

2. Gravitational force is conservative force, therefore work done in displacing a body from one place to another is independent of path. It depends only on initial and final positions. 

3. The gravitational force obeys Newton’s third law i.e.,