3A15.10 Pendulum in Sand

Demo Description:

This demo uses a pendulum that leaves marks in sand to demonstrate the periodic motion of a pendulum.

Equipment:

• Pendulum and sand apparatus
• Document camera

Demo location: H128-H5

Caution / Safety Info:

Please see the Safety Information page (link) regarding the following risks associated with this demonstration:

• general safety practices

Setup Procedure:

1. Remove the lid on the sand pit of the pendulum. Make sure it is on a level table!
2. Set up the needle of the pendulum:
   • Screw the appropriate needle head onto the metal shaft.
   • Using the plastic mount bar and the metal hook apparatus, hang the metal shaft above the sand pit.
3. Set up the document camera up to display the sand pit.
4. To level the sand: replace the needle end of the pendulum with the cylinder end. Screw it on most of the way, and slowly swing it across the sand pit until it repositions the sand into a concave pattern. replace the cylinder with the needle end when completed.

Demonstration Procedure:

1. Move the pendulum to the edge of the sand pit, and release it. Take note of the patterns the pendulum makes in the sand, and the different directions it will begin to oscillate in.
2. You can show that by adjusting the degree you release from, as well as whether you give the needle a nudge perpendicular to the direction of the swing, that it creates other patterns.

Notes:

• Do not give the pendulum extra force towards the center when releasing it, as this will cause it to oscillate outside of the sand pit.
• There is so much sand contained in the pendulum base. The sand is very fine, and can be difficult to clean if spread outside of the primary pendulum pit. Be cautious when operating the pendulum not to spread the sand