The Universal Law of gravitation:
Gravitational force:
All the heavenly bodies attract each other. There is a force which acts on. This force is called gravitational force.
In other words:
Gravitational force: The force attracting two objects is known as gravitational force.
Universal Law of Gravitaion:
The law of gravitation states that the force of attraction between any two objects is proportional to the product of their masses and inversely proportional to the square of the distance between them. The law applies to objects anywhere in the universe. Such a law is said to be universal.
This law gives a formula to find this force.
The value of G was found out by Henry Cavendish (1731 – 1810) by using a
sensitive balance.
The accepted value of G : 6.673 X 10-11 N m2 Kg-2
- The law is universal in the sense that it is applicable to all bodies, whether the bodies are big or small, whether they are celestial or terrestrial.
- The universal law of gravitation is given by Sir Isaac Newton.
IMPORTANCE OF THE UNIVERSAL LAW OF GRAVITATION
(i) The force that binds us to the earth;
(ii) The motion of the moon around the earth;
(iii) The motion of planets around the Sun;
(iv) The tides due to the moon and the Sun.
Centripetal force : When we moves a stone released with thread in a circular path with a certain speed, then it changes direction at every point. The change in direction involves change in velocity and acceleration. The force that causes this acceleration and keeps the body moving along the circular path is acting toward the centre. This force is called the centripetal force.