Formulas & tables/Physics/Gravitation/Gravitational acceleration at the surface

Gravitational acceleration at the surface

g=GMR2g = \dfrac{GM}{R^2}

Result unit: m/s²

What it describes

The gravitational acceleration at the surface of a body of mass M and radius R. It explains why g differs on every planet.

Symbols

gg
gravitational acceleration
[m/s²]
GG
gravitational constant
[N·m²/kg²]
MM
mass of the celestial body
[kg]
RR
radius of the body
[m]

Where it comes from

From the law of universal gravitation F=GMm/R² and F=mg: the mass m cancels, leaving g=GM/R².

When to use it

When you compute g for any body, compare the gravity of planets, or find the weight on another planet.

Example

g of Earth (M=5.97·10²⁴ kg, R=6.37·10⁶ m)?
Substitutiong = 6.674·10⁻¹¹·5.97·10²⁴ / (6.37·10⁶)²
Resultg ≈ 9.81 m/s².

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