Work & Energy · Physics

Elastic Potential Energy (Springs)

Springs store energy when stretched or compressed: \(U_s=\tfrac12 kx^2\).

This topic includes

Subtopics to master

Connect Hooke’s law to stored energy and solve multi-spring energy problems.

Law
Hooke’s Law
For an ideal spring: \(F=-kx\). The restoring force points opposite displacement from equilibrium.
  • Meaning of \(k\)
  • Equilibrium position
  • Direction/sign conventions
Energy
Spring Potential Energy Function
From \(F=-kx\), the stored energy is \(U_s=\tfrac12 kx^2\) (relative to \(x=0\)).
  • Where the \(x^2\) comes from
  • Work–energy connection
  • Graph \(U(x)\)
Systems
Multiple Springs
Combine springs in series/parallel (intro) and track total energy stored across elements.
  • Equivalent stiffness idea
  • Energy in each spring
  • Common setups
Meaning
Energy Storage and Release
A spring trades energy between \(U_s\) and kinetic energy; this powers launches and oscillations (preview).
  • Release from compression
  • Energy transfer picture
  • Real-world examples
Practice
Practice & Exercises
Solve energy problems with springs: compute \(U_s\), speeds, and compression distances.
  • \(U_s=\tfrac12 kx^2\) drills
  • Work vs energy interpretation
  • Spring launch problems
  • Multi-spring energy bookkeeping
  • Concept checks (signs, equilibrium)
Bridge
Toward Energy Conservation
With only conservative forces (springs + gravity), \(K+U_s+U_g\) is conserved — a powerful solving tool.
  • When conservation applies
  • Energy diagrams preview
  • Next topics link