Breakdance Power Move: Windmill Angular Momentum

Power Move

Setup

Launch torque 6.0

Limb extension 70%

Floor friction 0.12

Live Readouts

Angular velocity ω

0.0 rad/s

Moment of inertia I

0.00

Angular momentum L

0.00

Rotational KE

0.0 J

Revolutions

0.0

Status

Idle

How it works

A breakdance windmill spins the dancer's body (legs pinwheeling, torso and shoulders sweeping the floor) around a near-vertical axis. Like a figure skater pulling in their arms, the move is governed by conservation of angular momentum:

L = I·ω  (conserved between torque impulses)
I = Σ mᵢrᵢ²  (moment of inertia — mass × radius² summed over the body)
KE_rot = ½·I·ω²
dω/dt = −(b/I)·ω   (floor-friction damping, torque τ = −b·ω)

Extending the legs and arms increases the effective radius r of each body segment from the spin axis, which raises I. If no new torque is applied, L stays fixed, so ω = L / I must drop — the dancer visibly slows down. Tucking the limbs shrinks r, drops I, and (with L held constant) spins the dancer up again, exactly like a skater's pull-in spin.

Launch Windmill — applies a floor-push torque impulse that sets the initial angular momentum L.
Tuck / Extend limbs — changes the limb radius live, which changes I and instantly re-solves ω = L / I so momentum is conserved mid-spin, just like the skater effect.
Floor friction — every real windmill loses energy to the floor and air; higher friction drains L faster and the spin dies out sooner.

This is the same rigid-body mechanic (L = Iω, torque as dL/dt) used to analyse figure-skating spins, diving twists, and satellite reaction-wheel attitude control — a breakdance power move is a full-body demonstration of it.

Spin axis / body Floor sweep radius

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