Euler's Disk Wobble

1. Euler's Disk Wobble Materials: Euler's Disk or heavy coin; smooth concave surface What you do: Spin disk/coin and let it settle. What students see: The wobble gets faster just before it stops. Question: Why does the wobble speed up while the disk is losing energy? 2. Tablecloth Pull Materials: Smooth cloth; plastic dishes/cups What you do: Pull cloth quickly and horizontally from beneath the dishes. What students see: Dishes mostly stay in place. Question: Why didn't the dishes leave with the cloth? 3. Chain Fountain Materials: Long bead chain; cup; lower catch bin What you do: Pull a short chain end over the rim and let it fall. What students see: The chain rises above the cup before falling. Question: Why does the chain go up before gravity pulls it down?

Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share. Guiding questions: Question: Why does the wobble speed up while the disk is losing energy? Question: Why didn't the dishes leave with the cloth? Question: Why does the chain go up before gravity pulls it down?