the universe with an attractive force. The strength of this force of attraction was found to be directly proportional to the product of their masses and is inversely proportional to the square of the distance between them. In mathematical form, it can be written as: F GM M =− ( . ) - - - - Unit Gravitation m F F x y z → → m m Gravitational force of attraction between m and m F = − F which confirms Newton’s third law.
Important features of gravitational force: As the distance between two masses increases, the strength of the force tends to decrease because of inverse dependence on r . Physically it implies that the planet Uranus experiences less gravitational force from the Sun than the Earth since Uranus is at larger distance from the Sun compared to the Earth. F = G(m m ) r F Figure . Variation of gravitational force with distance The gravitational forces between two particles always constitute an action- reaction pair.
It implies that the gravitational force exerted by the Sun on the Earth is always towards the Sun. The reaction-force is exerted by the Earth on the Sun. The direction of this reaction force is towards Earth. Solution The force of attraction is given by F Gm m =− From the figure, r = m.
First, we can calculate the magnitude of the force F Gm m × × N It is to be noted that this force is very small. This is the reason we do not feel the gravitational force of attraction between each other. The small value of G plays a very crucial role in deciding the strength of the force. The force of attraction ( F ) experienced by the mass m due to m is in the negative ‘y’ direction ie., r j =− .
According to Newton’s third law, the