Sand pendulums are an easy and beautiful method for students of all ages to learn a bit about the harmonic motion. These devices are easy to build and can be adjusted to give a variety of patterns. A pendulum that begins with two point of support can alter the periods of the pendulum as it moves on two perpendicular axis at the same time. The video gives simple instructions on the materials needed and how to adjust the configuration to vary the design.

From science teacher Bruce Yeany, here’s another home made science demo that you can make and try at home: Sand pendulums – Lissajous patterns, named for French physicist Jules Antoine Lissajous.

Update: Yeany also shares how to make Lissajous patterns with light by using a small LED source, a dark room, and a camera with long exposure capabilities. He recommends leaving the shutter open “for times of about 15 seconds up to about 6 minutes.”

Further reading: Lissajous curves at Wolfram Mathworld, plus this interesting wikipedia note: “Not to be confused with spirographs, which are generally enclosed by a circular boundary, whereas Lissajous curves are enclosed by rectangular boundaries.”

Next: The Iron Genie Harmonograph, Eske Rex: Pendulum-Powered Drawing Machine, How to paint with ice skates, a light painting beginner’s guide, and Robert Howsare’s Drawing Apparatus.

And from Yeany: A home made string shooter & slow moving waves in rope.

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