Why does a spinning coin settle down?
Show answer & explanation
Answer: Friction dissipates energy
Gravity pulls it down — Wrong. Gravity provides downward force, but coin spins down because friction (air resistance + table contact) dissipates rotational energy.
Magnetism from table — Wrong. No magnetism involved (unless magnetic table). Coin settles because friction converts kinetic energy to heat, slowing rotation.
Friction dissipates energy ✓ — Correct! Spinning coin has rotational kinetic energy. Two friction sources dissipate it: (1) Air resistance—coin pushes air molecules as it spins. (2) Contact friction—edge touching table. Energy converts to heat and sound (vibration). As energy decreases, spin slows. Eventually insufficient angular momentum to maintain balance—falls flat. Faster initial spin = longer duration. Smooth table/coin = less friction, longer spin!