Forces and elasticity

This lesson covers: 

  1. How forces can deform objects
  2. What work and energy transfer involve
  3. Hooke's Law and springs
  4. Equilibrium of forces

Work and energy transfer during deformation

Deforming an object requires energy to be transferred into it and work to be done on it.

Diagram showing energy transfer in a stretched spring and compressed spring with labels for kinetic energy and elastic potential energy.
  1. For example, stretching a spring transfers energy from you to the spring's elastic potential energy stores.
  2. When the spring rebounds, energy transfers back into kinetic energy.

Hooke's Law - force and extension

Graph showing the linear relationship between force and extension according to Hooke's Law.

Hooke's Law applies to springs. It states:

The extension of a spring is directly proportional to the force applied to it.


The relationship can be described by:

Force (N) = spring constant ×extension (m)

F = k ×e

This linear relationship only applies up to a certain maximum force.

Equilibrium occurs when forces are balanced

Diagram showing a mass hanging from a spring with opposing forces labeled as spring force and weight.
  1. Equilibrium means balanced, opposing forces.
  2. When a mass hangs from a spring, the downward weight force equals the upward spring force.
  3. The forces are balanced, so the spring remains stationary.