Mechanics
Gravitational field strength
The force per unit mass, which is the acceleration a small test mass would experience.
The Formula
g = G x M / r^2 = F / m
The force per unit mass, which is the acceleration a small test mass would experience.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| g | Field strength | metres per second squared | Acceleration due to gravity at that distance. |
| M | Source mass | kilograms | The body creating the field. |
| r | Distance from centre | metres | How far out from the source you are measuring. |
What Each Symbol Means
gmetres per second squared
Field strength
Acceleration due to gravity at that distance.
Mkilograms
Source mass
The body creating the field.
rmetres
Distance from centre
How far out from the source you are measuring.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate a gravitational force page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate A Gravitational Force, filed under Science. Every number the guide produces comes from substituting into this one line.