Physics 12 · Physics · Lesson 3.2
Gravitation
- Level
- Grade 12
- Reading time
- 13 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
Newton's law of gravity.
What is Newton’s law of universal gravitation?
Short answer
Newton’s law of universal gravitation states that every mass attracts every other mass with a force proportional to the product of their masses and inversely proportional to the square of the distance between them: F = Gm₁m₂/r². G is the gravitational constant. This single law explains falling objects, the Moon’s orbit, and the motion of planets.
Concept preview
What you will be able to do
- 01Apply the universal law of gravitation
- 02Relate gravitational field strength to mass and radius
- 03Use the inverse-square law to compare gravitational forces
Newton's leap of genius was realising that the force pulling an apple to the ground is the very same force keeping the Moon in orbit — gravity reaches across space. His law of universal gravitation states that every mass attracts every other mass with a force , where is the universal gravitational constant and is the distance between the centres. Bigger masses pull harder; greater distance pulls weaker.
School Plan
Gravitation
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Related topics
Frequently asked questions
- What does "inverse-square" mean here?
- Doubling the distance between two masses reduces the gravitational force to a quarter of its value.
- Why don’t we feel gravity between everyday objects?
- G is extremely small, so gravitational forces are only noticeable when at least one mass is very large, like a planet.