3C20.43 - Coin in a Balloon
Put a dime or a quarter in a balloon. Blow the balloon up and tie it off. Rotate the balloon so that the coin starts to travel in a circle inside the balloon. The edges of the coin on the balloon will create a sound whose frequency depends on the velocity of the coin inside the balloon.
- Bobby Mercer, "Rubber Maraca", Junk Drawer Physics, p. 69.
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