Sheri draws the complex sand pendulum pattern
Don set up the complex sand pendulum in the math room. The strings at the top are adjustable so one can change the total height of the pendulum (pendulum #1). The strings come together to form a smaller pendulum (pendulum #2) and are held together by an alligator clip so this height can be changed. The sand is in a ketchup bottle. When the ketchup bottle is pulled off center, the pendulums will swing, perpendicularly, forming "Lissajous" figures like the one shown in Sheri's drawing. The pattern in the sand is determined by the ratio of the frequencies of the 2 pendulums (in this case 3:2).
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