Gravitation

Tanusri Gururaj, Academic content writer of Physics at Edumarz

• Centripetal force:

This force acts towards the centre and keeps the body moving in a curved path.

Example:

During the motion of the moon around the Earth, there is a centripetal force provided by the force of attraction of the Earth.

In the absence of this force, the moon would follow a straight path. 

• The universal law of gravitation:

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

If there are two objects X and Y with mass M and m respectively, separated by a distance ‘d,’ then according to this law, 

F ∝ Mm and F ∝ 1/d2

Combining them we get

F ∝ Mm/d2 

Or F = GMm/d2

Where F = force of attraction between the objects and G = constant of proportionality known as universal gravitational constant. 

SI unit of G is given by: N m2 Kg-2.

The value of G is given by: 6.67 x 10-11 N m2 Kg-2.

• This law explains several concepts like:

1. The moon revolving around the Earth

2. Planets revolving around the Sun

3. The force which binds us to the Earth