• Spinwell pixel-art physics sticker – angular momentum conservation, arms in faster

IndexWaves, Chaos & MatterSticker

Spinwell

Angular Momentum Physics

\[L = I\omega\]
$4.99 USD
$4.99 USD
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Why does a skater spin faster when she pulls her arms in? Spinwell knows angular momentum, L = Iω, is conserved when no outside torque acts. Tucking in her arms lowers her moment of inertia I, so her spin rate ω must rise to keep L the same. Divers and collapsing stars use the same rule. A 3" pixel-art sticker; equation, symbols and sources in the physics panel below.

Size
Surface

Flat $6 shipping worldwideMade to order, ships in 2–5 business days

Details

Size3″ × 3″

3″ × 3″ kiss-cut sticker.

Shipping

Flat $6 shipping on every order, worldwide, whatever's in it.

Delivery times & where we ship

Returns & replacements21 days

Every item is printed to order, so we can’t accept returns or exchanges for change of mind, or if you ordered the wrong size or colour.

Print defect, misprint, damage or the wrong item? We’ll send a free replacement, or a refund if you prefer. Report it within 21 days of delivery with a photo; no need to send it back.

Full refund & replacement policy

The physics

Spinwell is a skater who knows L = Iω.

With no external torque, angular momentum is conserved: I₁ω₁ = I₂ω₂. Pull the arms in, I drops, ω rises. Arms out, you slow.

On the sticker the arms are tucked, motion lines whirl, and the ω arrow is bigger. The inset states the conservation law.

Same physics that keeps a spinning bicycle wheel upright and a neutron star spinning for millennia.

Arms in. Faster.

Equations

\[L = I\omega\]
\[I_1\omega_1 = I_2\omega_2\quad(\tau=0)\]
SymbolMeaningUnit
\(L\) angular momentum about the spin axis \(\mathrm{kg m^2 / s}\)
\(I\) moment of inertia about that axis \(\mathrm{kg m^2}\)
\(\omega\) angular speed \(\mathrm{rad/s}\)
\(\tau\) external torque about the axis \(\mathrm{N m}\)

Sources

  1. Halliday, Resnick & Walker, Fundamentals of Physics, Ch. on rotation / angular momentum
  2. Taylor, Classical Mechanics (2005), Ch. on rigid-body rotation
  3. Wikipedia, Conservation of angular momentum

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