Hooke Law

Hooke’s law says that when a spring is stretched or compressed a small amount, the force it exerts grows in direct proportion to that displacement. The minus sign means the force points back toward the spring’s natural length, so it is a restoring force. This works well for ordinary springs and other elastic objects as long as they are not stretched too far, because in that range the material resists deformation in a nearly linear way.

Use this formula when you need the force from a spring, or the displacement caused by a known spring force, in simple elasticity problems. It appears in physics questions about springs, oscillations, force sensors, and any situation where an object obeys approximately linear elastic behavior.

• Forgetting the minus sign, which shows the force is opposite the displacement
• Using centimetres instead of metres without converting first
• Applying Hooke’s law to a spring stretched beyond its elastic limit