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Beautiful visual loop showing visual pattern consonance and dissonance
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.