Aliasing in Pendulum Waves

The Pendulum Waves demonstration consists of 15 uncoupled pendula of monotonically increasing lengths dancing together to produce visual traveling waves, standing waves, beating, and random motion. The demonstration is set in motion by releasing all the pendula from the same initial angle.
This is a simulation of pendulum waves (top-view) with a selected number of 10 to 20 uncoupled pendula and a period of 30 to 90 seconds. The plotted dots represent individual pendulums viewed from above. The light grey line plotted underneath is an approximated function of the wave. This demonstration shows how aliasing produces the visual effects in the pendulum wave demonstration as seen on YouTube and at Stan Wagon's demonstration.
Slowing the step speed of the demonstration so that Time passes 1 unit/second produces the best results.

THINGS TO TRY

SNAPSHOTS

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DETAILS

R. E. Berg, “Pendulum waves: A demonstration of wave motion using pendula,” American Journal of Physics, 59(2), 1991 pp. 186–187.

J. A. Flaten and K. A. Parendo, “Pendulum waves: A lesson in aliasing,” American Journal of Physics, 69(7), 2001 pp. 778–782.