Pendulum Compositions

Swinging Composer

Introduction

Play music in time with the Exploratorium's Pendulum Snake. The exhibit has ten pendulums each with a different period. The pendulum periods are arranged so that if they start off together, they all come back to swing together after 30 seconds, you can hear this in the music.

Material

10 pendulums, one which makes 15 swings in 30 seconds, another that makes 16 swings and so on to one that makes 24 swings.

10 people each with a musical instrument, for example a pitch pipe or a palm pipe,

To Do and notice

Have each person play their musical note every time the pendulum reaches one end of its swing.

Start all the pendulums together and listen to what happens.

Here is the pendulum's composition using pitch pipes.

Sound File .wav

Palm Pipe pendulum .wav

What's Going On?

The pendulums and played notes start off all together. Then slowly the pendulums drift out of phase. After 30 seconds they all return to synchrony once again.

Listen at 15 seconds and note that half of the pendulums have returned to swing together, the other half are 180 degrees out of phase and so their notes are not played together,

Math Root

For the mathematics of pendulums and pipes go here.