Newton’s law of Gravitation
Hello students, in this article we are going to deal with the most important and universal law which gives us mathematical form of the gravitational force between the any two objects. This law is valid for all the interacting particles in the universe.
Consider the two objects A and B of masses m1, and m2 separated by distance ‘r’ from their centres as shown below,
These objects exerts gravitational force on each other which depends upon masses and distance between objects.
According to Sir Isaac Newton, “Every object in the universe attracts every other object in the universe with a fixed force, which is 1) directly proportional to product of masses of two objects and 2) inversely proportional to square of distance between their centres.”
Where, G is constant of proportionality known as universal gravitational constant.
The value of G in SI System is 6.67 x 10-11 Nm2/Kg 2 which was discovered by Hinny Cavendish. In CGS System, value of G is 6.67 x 10-8 dyne cm2/g2
Ratio of SI Unit of G & CGS Unit of G is 1000
The magnitude of the gravitational force is very small as compared to other forces, hence the objects around us not found to get attracted towards each other. For illustration of the same, consider two objects each of mass 1 kg separated by 1 m, then by Newton’s law of gravitation the gravitational force between them can be given as,
Magnitude of force is very small as compared to the weight object and other forces present around the object, hence though object of 1 kg is comparatively large for us, but the gravitational force between two such objects is very small that can be neglected.
Let’s learn more with following numerical,
Eg.1) Harsh and Mayank both of masses 25 kg and 35 kg are enjoying see saw of length 2 m in the garden. Find the gravitational force between them.
Ans: m1= 25 kg, m2= 35 kg, r= 2 m.
By Newton’s law of gravitation the gravitational force between them can be given as,
The force of attraction between Harsh and Mayank is 14.6 × 10-9 N