🪝 Hooke's Law Calculator (F = kx)
Find the restoring force of a spring (F = kx), or solve for the spring constant or extension.
Force F
10 N
Hooke’s law: F = k·x (restoring force = spring constant × extension). Elastic PE = ½·k·x². 🔒 Computed in your browser.
How the hooke's law calculator (f = kx) works
Hooke’s law says a spring’s restoring force is proportional to its extension: F = kx, where k is the spring constant (stiffness) and x the extension or compression. Enter any two and the tool solves for the third. The energy stored is ½kx².
Valid within the elastic limit — stretch a spring too far and it deforms permanently and Hooke’s law breaks down. A stiffer spring has a larger k.
Frequently asked questions
What is Hooke’s law?
The force a spring exerts is proportional to how far it’s stretched or compressed: F = kx. Double the extension, double the force — up to the elastic limit.
How do I find the spring constant?
Rearrange to k = F/x. A spring needing 10 N to stretch 0.05 m has k = 200 N/m. Enter force and extension to get k.
What is the spring constant’s unit?
Newtons per metre (N/m). A larger k means a stiffer spring that resists stretching more.
How much energy is stored in a stretched spring?
Elastic potential energy = ½kx². For k = 200 N/m stretched 0.05 m, that’s ½ × 200 × 0.05² = 0.25 J.
When does Hooke’s law stop working?
Beyond the elastic limit, where the material deforms permanently. Then force is no longer proportional to extension.