Uploaded January 2022 | Updated September 2026, 1 week ago
These pendulums’ beat-mode period results from the interaction of in-phase and out-of-phase oscillations.
Two pendulums with a weak degree of coupling produce two eigenfrequencies, which in turn lead to a complex motion that is not a simple sinusoid. But the motion can be analyzed as a sum of two sinusoidal motions, each of which obeys the simple equations of Simple Harmonic Motion, and oscillates at its eigenfrequency.
The beat period depends on distance between repelling magnets. When the distance is decreased
by about 8%, or 0.5 centimeter, the beat period is reduced nearly by half.
A few years ago, when I got started with Lego, I learned from YouTube contributor @KEvronista
about low-friction knife-edge pivots, similar to the ones used in this video.
Chapters
00:00 Preview
00:21 In-Phase Oscillations
00:51 In-Phase Model
01:05 Out-of-Phase Oscillations
01:31 Out-of-Phase Model
01:46 Beat-Mode Oscillations — 10 Sec. Beat Period
02:40 Animation
03:12 Beat-Mode Model — 10 Sec. Beat Period
03:26 Beat-Mode Oscillations — 6 Sec. Beat Period
04:01 Beat-Mode Model — 6 Sec. Beat Period
Watch coupled pendulums powered by electrical charges, magnetic fields, and gravity:
youtube.com/playlist?list=PLCbYhDNjOviFM5R3bQdxGR2tT25IJBWiE
Music
Title: When Sunny Gets Blue
Artist: McCoy Tyner, McCoy Tyner Trio
Album: When Sunny Gets Blue, Released 1963, UMG Recordings, Inc.
#CoupledOscillators #energytransfer #beatmode #physicswithlego
These pendulums’ beat-mode period results from the interaction of in-phase and out-of-phase oscillations.
Two pendulums with a weak degree of coupling produce two eigenfrequencies, which in turn lead to a complex motion that is not a simple sinusoid. But the motion can be analyzed as a sum of two sinusoidal motions, each of which obeys the simple equations of Simple Harmonic Motion, and oscillates at its eigenfrequency.
The beat period depends on distance between repelling magnets. When the distance is decreased
by about 8%, or 0.5 centimeter, the beat period is reduced nearly by half.
A few years ago, when I got started with Lego, I learned from YouTube contributor @KEvronista
about low-friction knife-edge pivots, similar to the ones used in this video.
Chapters
00:00 Preview
00:21 In-Phase Oscillations
00:51 In-Phase Model
01:05 Out-of-Phase Oscillations
01:31 Out-of-Phase Model
01:46 Beat-Mode Oscillations — 10 Sec. Beat Period
02:40 Animation
03:12 Beat-Mode Model — 10 Sec. Beat Period
03:26 Beat-Mode Oscillations — 6 Sec. Beat Period
04:01 Beat-Mode Model — 6 Sec. Beat Period
Watch coupled pendulums powered by electrical charges, magnetic fields, and gravity:
youtube.com/playlist?list=PLCbYhDNjOviFM5R3bQdxGR2tT25IJBWiE
Music
Title: When Sunny Gets Blue
Artist: McCoy Tyner, McCoy Tyner Trio
Album: When Sunny Gets Blue, Released 1963, UMG Recordings, Inc.
#CoupledOscillators #energytransfer #beatmode #physicswithlego
