Universal law of gravitation
- Olympiad · NSEJS
The universal law of gravitation says that any two bodies pull each other with a force that grows with their masses and falls with distance.
Newton stated it. For two bodies of masses m₁ and m₂, with centres a distance d apart, the force is:
- F = G m₁ m₂ / d².
G is the universal gravitational constant. It has the same value everywhere. The law is called universal because it holds for every pair of bodies, big or small, on Earth or in space. G is very small. That is why you do not feel the pull between two books, but you do feel the pull of the huge Earth. That pull is your weight.
The d² part is called an inverse square law. Double the distance and the force drops to a quarter. Treble it and the force drops to a ninth.
A small example
Two bodies pull each other with a force F. One mass is doubled, and the distance between them is also doubled. What is the new force?
- Doubling one mass makes the force 2F.
- Doubling the distance divides the force by 2² = 4.
- New force = 2F ÷ 4 = F/2. The force halves.
You do not need the value of G for questions like this. Only the ratios matter. The same law explains why the Moon goes round the Earth.
Where it fits
This goes beyond the Class 10 board syllabus. HBCSE's Junior Science syllabus lists it under gravitation. That syllabus is for NSEJS, which the Indian Association of Physics Teachers (IAPT) conducts.
Sources
Facts last checked against these sources on 30 September 2026.
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