Hooke's Law

While investigating springs Robert Hook discovered:

When something is stretched with a steady force the length of the object
being stretched will increase steadily as well.
This will be the case until the object is permanently stretched and can no longer retake it's original shape once the force is removed.

Hooke's Law: Extension is proportional to stretching force (load)'
For example: doubling the force doubles the extension.
Trebling the force trebles the extension.

This law is true for most materials!

© Cranfield University

Note:

Extension
means
the increase
in length
not the total
length of the
object!