Properties of Gravitational Force
The Gravitational force is a force that attracts any two objects with mass. Gravitational force is an attractive why because it always tries to pull masses together. It never pushes them apart. In fact, every object, every human being is pulling on every other object in the entire universe, this is called as Newton’s Universal Law of Gravitation, which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Thus the magnitude of the gravitational force F those two particles of masses \({{m}_{1}}\) and \({{m}_{2}}\) are separated by a distance exert on each is given by:
\(F\propto \frac{{{m}_{1}}{{m}_{2}}}{{{r}^{2}}}\Rightarrow F=G\frac{{{m}_{1}}{{m}_{2}}}{{{r}^{2}}}\)1) It is always attractive in nature while electric and magnetic force can be attractive or repulsive.
2) It is independent of the medium between the particles while electric and magnetic force depend on the nature of the medium between the particles.
3) It holds well over a wide range of distances. It is found true for interplanetary to inter atomic distances.
4) It is a central force i.e. acts along the line joining the centers of two interacting bodies.
5) It is a two body interaction i.e. gravitational force between two particles is independent of the presence or absence of other particles, so the principle of superposition is valid i.e. force on a particle due to number of particles is the resultant of forces due to individual particles i.e. \(\overrightarrow{F}=\overrightarrow{{{F}_{1}}}+\overrightarrow{{{F}_{2}}}+\overrightarrow{{{F}_{3}}}+\overrightarrow{{{F}_{4}}}+……….\) while nuclear force is many body interaction.
6) It is the weakest force in nature: As \({{F}_{Nuclear}}>{{F}_{Electromagnetic}}>{{F}_{Gravitational}}\)
7) The ratio of gravitational force to electrostatic force between two electrons is of the order of\({{10}^{-43}}\).
8) It is a conservative force i.e. work done by it is path independent or work done in moving a particle round a closed path under the action of gravitational force is zero.
9) It is an action reaction pair i.e. the force with which one body (earth) attracts the second body (moon) is equal to the force with which moon attracts the earth. This is in accordance with Newton’s third law of motion.