- This law states that every particle of matter in this universe attracts every other particle with a force.
- This force is directly proportional to the product of their masses and inversely proportional to the square of the distance between the centres of these masses.
- The direction of the force acts along the line joining the masses.
- The force between the masses is always attractive and it does not depend on the medium where they are placed.
Let, m1 and m2 be the masses of two bodies A and B placed r metre apart in space
Force
F ∝ m1*m2
F ∝ 1 / r 2
On combining the above two expressions
F ∝ (m1 m 2) / (r 2)
F = (G*m 1 * m 2)/r 2
Where G is the universal gravitational constant.
SI unit is 6.674 * 10 – 11 Nm 2 kg – 2
Application of Newton’s law of gravitation
- Dimensions of the heavenly bodies can be measured using the gravitation law. Mass of the Earth, the radius of the Earth, acceleration due to gravity, etc. can be calculated with higher accuracy.
- Helps in discovering new stars and planets.
- One of the irregularities in the motion of stars is called ‘Wobble’ which leads to the disturbance in the motion of a planet nearby.
- In this condition, the mass of the star can be calculated using the law of gravitation.
- Helps to explain germination of roots is due to the property of geotropism which is the property of a root responding to gravity.
- Helps to predict the path of the astronomical bodies.