3A10.10 Adjustable Length Pendulum


Simple harmonic motion, conservation of energy


A ball is suspended from a pivot so that it can swing freely. The length of the pendulum is adjustable. For small amplitude, the motion of the pendulum as a function of time is approximately simple harmonic motion. Also, the pendulum can be used to show conversion of potential to kinetic energy.



  • [1] Ball attached to a string
  • [1] Lab stand
  • [1] 90-degree clamp
  • [1] Screw clamp (used as a pivot)

Classroom Assembly

  1. Suspend the string on a screw clamp. 
  2. Attach the screw clamp to a lab stand.
  3. Adjust the length of the pendulum as necessary.


  1. Displace the ball sideways from its equilibrium position and release it.


Additional Resources


  • PIRA 3A10.10


  • Don't attempt this at home!

Last revised

  • 2018


Related AV

Related demos


If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.