Grade 11 · Theory
Newton's law of universal gravitation
Newton's laws · about 3 min
Visual overview: Newton's law of universal gravitationEvery mass attracts every other mass, and the same law explains falling apples and orbiting planets.
Key points- F = Gm₁m₂/r², with G = 6,7 × 10⁻¹¹ N·m²·kg⁻².
- r is measured centre to centre, not surface to surface.
- Weight is the gravitational force on a mass: Fg = mg.
- Doubling the distance quarters the force (inverse square).
- Universal gravitational constant (G).
- Weight — the gravitational force on an object.
EXAM TIP
mass is constant everywhere, weight is not — an object on the Moon has the same mass but about a sixth of the weight.