3A70.25 Spring-Coupled Pendula


Coupled oscillators


Two pendula oscillate, coupled together by a spring. The moments of inertia of the pendula can be adjusted by moving two masses. The coupling can be changed by changing the pivot separation and coupling points.



  • [2] Rotational motion sensor
  • [2] Pendulum rod with mounting hardware
  • [2] Mass with set screw
  • [1] Spring with clamps
  • [2] Lab stand
  • [2] 90-degree clamp
  • [1] Aluminum rod
  • (Optional) [1] Computer with Logger Pro
  • (Optional) [1] LabPro or LabQuest Mini system

Classroom Assembly

  1. Mount the aluminum rod between the lab stands using the 90-degree clamps.
  2. Mount the rotational motion sensors on the aluminum rod.
  3. Attach the pendulum rods to the motion sensors.
  4. Attach the spring and the masses to the pendulum rods.
  5. (Optional) Connect the LabPro or LabQuest mini system to the motion sensors and the computer. If using the LabPro system, plug it into mains power.


  1. Start with one pendulum stationary and the other moving. 
  2. (Optional) Take data using Logger Pro.
  3. Observe the time evolution of the system.
  4. Change the system in some way (moment of inertia, coupling, initial conditions) and repeat the experiment.


Additional Resources


  • PIRA 3A70.25


  • Don't attempt this at home!

Last revised

  • 2020


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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.