Concepts

Simple harmonic motion

Overview

A physical pendulum undergoes simple harmonic motion when displaced by a small angle. The oscillations are no longer simple harmonic motion when it is released from a large angle. The pendulum's pivot point can be set at different positions, and two masses can be attached to change the moment of inertia.

Details

Equipment

• [1] Physical pendulum table
• [1] Physical pendulum stand
• [1] Pivot screw
  
• [1] Wingnut
• [2] C-clamp
• [1] Metal physical pendulum with holes
• (Optional) [1] Stopwatch
• (Optional) [2] Screw
• (Optional) [2] Circular mass
• (Optional) [2] Wingnut

Classroom Assembly

1. Place the pendulum stand on the edge of the table.
2. Clamp the stand to the table using C-clamps.
3. Attach the pivot screw to the pendulum stand.
   
4. Mount the pendulum at any of the holes.
5. Secure the mounting using a wingnut.

Script

1. Raise the metal pendulum to a small angle (about 20° or less) and release it.
   
2. Now raise the metal pendulum to a large angle and release it.

1. Attach a mass or two using screws and wingnuts and repeat the experiment.
2. Change the pendulum pivot position and repeat the experiment.
3. Show using a stopwatch that when the assumption of small oscillations is violated, the pendulum does not undergo simple harmonic motion. The period should vary with oscillation amplitude.

Additional Resources