8.1 Introduction

Gravitation or just gravity is the force of attraction between any two objects. All the objects in the universe attract each other with a certain amount of force, but in most cases, the force is too weak to be observed due to the very large distance of separation. Besides, gravity’s range is infinite, but the effect becomes weaker as objects move away. This force of attraction was first observed by Sir Isaac Newton and was presented as Newton’s law of gravitation in the year 1680.

However, gravitation can generally exist in two main instances.

• Gravitation may be the attraction of objects by the earth. For example,  If a ball is thrown upwards, it reaches a certain height and falls downwards because of the earth’s gravity.
• Gravitation may be the attraction of objects in outer space. For example, the force of attraction between the other planets and the sun.

Gravitation or gravity is an all-pervasive universal gravitational force that attracts a body towards the centre of the Earth or any other physical body having a mass. Along with electromagnetism and strong and weak nuclear forces, Gravitation constitutes the four fundamental forces of nature. Although gravitational force is the weakest known force of the four but is absolutely crucial as it controls all the trajectories of the bodies in the universe and the cosmos.