The Pendulum

by John
(Washington State)

For my 3rd grade science project I created a pendulum using a ladder and a two-liter soda bottle. The soda bottle was filled with Elmer's glue mixed with food coloring and then set into motion. As the pendulum swings back and forth large sheet of butcher paper underneath the ladder reveals the movement pattern of the pendulums motion.

In addition I setup a display covering the different types of Pendulums and my source of inspiration, the movie "The Pit and the Pendulum". Definitely my
favorite science project over the years and one I'm eager to share with my son when he is older.

Barry's Response - Yes John. Pendulums are neat things. Especially the device devised by Léon Foucault, depicted above.

What seems so simple these days took some effort to devise and explain at one point. What makes the pendulum trace out its path as shown rather than simply swing back and forth like a clock's pendulum?

The
rotation of the earth. The clock is designed to allow motion in one direction only, otherwise it would swing freely like this one as well. This one swings so that in real space it does not change its direction. Instead the earth moves under it while the plane of the pendulum motion remains fixed in space.

This Wikipedia article gives you a better insight into how this happens...complete with
physics and math formulae and other animated depictions.

https://en.wikipedia.org/wiki/Foucault_pendulum

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