⛸️ Conservation of Angular Momentum
Angular Momentum Simulator: The Spinning Skater Effect
This angular momentum simulator shows the figure-skater effect. With no external torque, angular momentum L = I·ω is conserved, so when the spinning skater pulls their hand masses inward the moment of inertia I drops and the angular speed ω must rise to compensate — they spin faster with no extra push. Drag the arm radius in and out and watch the platform whirl up or slow down while a card holds L essentially constant and shows I, ω, and the rotational kinetic energy ½Iω². A subtle point the lab makes clear: that KE actually increases when you pull in, because your muscles do work hauling the masses inward against their inertia — energy that returns when you let them out. The same conservation law spins a collapsing stellar core into a millisecond pulsar. Predict whether the spin speeds up or slows before you move the arms.
What you can do in this simulation
- Pull a spinning skater's arms in and out and watch the spin rate change to conserve L = Iω
- A card shows arm radius, moment of inertia, angular speed, angular momentum, and rotational KE
- See L stay essentially constant while I and ω trade off inversely
- Notice rotational KE rises when you pull in — the work your muscles do against inertia
- Predict mode: call faster / slower / same before moving the arms; arms-in, arms-out, and spin-harder presets
Concepts covered
angular momentum · conservation of angular momentum · moment of inertia · rotational kinetic energy · figure skater effect · pulsar spin-up · rotational dynamics
Related simulations
- Gyroscope Precession Simulator: Why Spinning Tops Don't Fall
- Captain America Shield Physics — Ricochet & Spin
- JEE Mechanics Challenge — Forces & Motion Practice
- Acoustics & Sound Waves — Interactive Simulator
- Black Hole Simulator — Gravity & Spacetime
- Brachistochrone Curve Simulator - Fastest Ramp
Browse all Physics simulations →
Free to use in your browser — no signup required. Found a bug or have an idea to make it better? Tell us.
Finished experimenting?
Save one completion to this browser's signed guest ledger, or directly to your account when signed in.