Mechanics
Hooke's Law
The restoring force is the spring constant times the displacement from the natural length, directed back toward equilibrium.
The Formula
F = -k x
The restoring force is the spring constant times the displacement from the natural length, directed back toward equilibrium.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| F | Restoring force | — | The force the spring exerts, in newtons. |
| k | Spring constant | — | Stiffness of the spring, in newtons per metre. |
| x | Displacement | — | Distance from the natural length, in metres. |
What Each Symbol Means
F
Restoring force
The force the spring exerts, in newtons.
k
Spring constant
Stiffness of the spring, in newtons per metre.
x
Displacement
Distance from the natural length, in metres.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate a spring 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 Spring Force, filed under Science. Every number the guide produces comes from substituting into this one line.