Coin Vortex in a Funnel
Coin circles faster as it spirals inward.
Teaching & key ideas
What you do: Launch coin around the rim.
What students see: Coin circles faster as it spirals inward.
Why it works: Gravitational potential energy becomes kinetic energy as radius decreases.
Question to ask: Why does the coin move faster near the middle?
Lesson flow
Predict → demonstrate → observe → briefly explain → ask: Why does the coin move faster near the middle?