Physics
Newton's second law
The core relation. Multiply mass by acceleration to get the net force. Both inputs must be in SI units, kilograms and metres per second squared, for the answer to appear in newtons.
The Formula
F = m a
The core relation. Multiply mass by acceleration to get the net force. Both inputs must be in SI units, kilograms and metres per second squared, for the answer to appear in newtons.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| m | Mass of the object | kilograms | In kilograms. Using grams by mistake inflates the force a thousandfold. |
| a | Acceleration of the object | metres per second squared | In metres per second squared. 3 m/s^2 is about 0.30591486389337846 g. |
| F | Net force acting on the object | newtons | In newtons, where 1 N = 1 kg m/s^2. A 1200 kg car at 3 m/s^2 needs 3600 N. |
What Each Symbol Means
mkilograms
Mass of the object
In kilograms. Using grams by mistake inflates the force a thousandfold.
ametres per second squared
Acceleration of the object
In metres per second squared. 3 m/s^2 is about 0.30591486389337846 g.
Fnewtons
Net force acting on the object
In newtons, where 1 N = 1 kg m/s^2. A 1200 kg car at 3 m/s^2 needs 3600 N.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate 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 Force, filed under Science. Every number the guide produces comes from substituting into this one line.