Pendulum LOOP

[Rick Walker <looppool@cruzio.com>]

Beautiful visual loop showing visual pattern consonance and dissonance


TinyURL.com/pendulumLOOP


What it shows: Fifteen uncoupled simple pendulums of monotonically 
increasing lengths dance together to produce visual traveling waves, 
standing waves, beating, and random motion. One might call this kinetic 
art and the choreography of the dance of the pendulums is stunning! 
Aliasing and quantum revival can also be shown.

How it works: The period of one complete cycle of the dance is 60 
seconds. The length of the longest pendulum has been adjusted so that it 
executes 51 oscillations in this 60 second period. The length of each 
successive shorter pendulum is carefully adjusted so that it executes 
one additional oscillation in this period. Thus, the 15th pendulum 
(shortest) undergoes 65 oscillations. When all 15 pendulums are started 
together, they quickly fall out of sync—their relative phases 
continuously change because of their different periods of oscillation. 
However, after 60 seconds they will all have executed an integral number 
of oscillations and be back in sync again at that instant, ready to 
repeat the dance.

Setting it up: The pendulum waves are best viewed from above or down the 
length of the apparatus. Video projection is a must for a large lecture 
hall audience. You can play the video below to see the apparatus in 
action. One instance of interest to note is at 30 seconds (halfway 
through the cycle), when half of the pendulums are at one amplitude 
maximum and the other half are at the opposite amplitude maximum.