Prof. Muni Mahendra Kumar
Newton, in his law of gravitation, stated that every particle in the universe attracts all other particles of the universe towards itself and the force of attraction is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.[1] This is also known as 'inverse square law'. This concept of gravitation presupposes action at a distance and postulates the existence of a force of attraction between material bodies. For instance, a mass such as the earth or the sun, is surrounded by a space in which there is a latent force ready to act upon and produce movement of a body that penetrates into the space. In consequence, the body falls towards the mass, as if attracted by it. This power of attraction exists permanently in the space near the mass even if there is no body manifesting its existence. The region of space surrounding a mass thus constitutes the gravitational field which imparts a uniform acceleration known as the acceleration due to gravity to all bodies located in that field The mass seems to act at a distance since the attraction is exerted even through vacuum where there is no ponderable matter, as for example, in the case of the sun attracting the planets.[2] Thus, Newton was able to explain the motion of planets in the space as well as freely falling bodies (such as apples in orchards) with the help of this law of gravitation.
Another important law which was enunciated by Newton was the 'law of inertia', which stated that 'a body at rest continues to remain at rest and a body in uniform rectilinear motion continues to be in motion, and a change in the state of rest or motion can be brought only by exerting some external force.' Thus when a body is started or stopped suddenly, a jerk is felt. This is due to the force of inertia.
