Mechanics
Work to separate two masses
The energy needed to pull the two masses apart to infinite separation.
The Formula
W = G x m1 x m2 / r
The energy needed to pull the two masses apart to infinite separation.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| W | Separation energy | joules | Work required to move the masses infinitely far apart. |
| G | Gravitational constant | newton metre squared per kilogram squared | Universal constant. |
| m1, m2 | The two masses | kilograms | Masses being separated. |
| r | Separation | metres | Starting centre-to-centre distance. |
What Each Symbol Means
Wjoules
Separation energy
Work required to move the masses infinitely far apart.
Gnewton metre squared per kilogram squared
Gravitational constant
Universal constant.
m1, m2kilograms
The two masses
Masses being separated.
rmetres
Separation
Starting centre-to-centre distance.
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.