3A50.45 Damped Physical Pendulum


Damped harmonic motion, eddy currents


A magnetic mass hangs on the end of a swinging rod. A movable copper plate damps the oscillations. The rod is connected to a rotational motion sensor, which can transmit the data to a computer for graphing.



  • [1] Steel mass on a rod
  • [1] Rare earth magnet
  • [1] Copper plate on a wooden block
  • [1] Rotational motion sensor and rod-mounting hardware
  • [1] Aluminum rod
  • [1] 90-degree clamp
  • [1] Lab stand
  • [1] LabPro interface with AC adapter and USB cable
  • [1] Computer with Logger Pro

Classroom Assembly

  1. Turn on the computer and start Logger Pro.
  2. Put the magnet on the steel mass.
  3. Mount the rod on the rotational motion sensor.
  4. Mount the rotational motion sensor on the lab stand using the aluminum rod and 90-degree clamp.
  5. Connect the LabPro interface to the rotational motion sensor, the computer, and power.
  6. Set up and test the sensor in Logger Pro.


  1. Start the pendulum oscillations and start data collection.
  2. Change the damping by altering the magnet-copper separation and repeat.


Additional Resources


  • PIRA 3A50.45


  • Don't attempt this at home!

Last revised

  • 2020


  • The rotational motion sensor drifts its origin over time.

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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.