This activity demonstrates that sound is produced by vibrations. A vibrating tuning fork transfers its motion to a suspended ping pong ball, making the otherwise invisible vibrations of sound waves visible.

1. Attach a ping pong ball to a piece of string.
2. Suspend the string so the ball hangs freely (use a clamp stand or tape the string to a desk).
3. Strike a tuning fork gently on a firm but padded surface, such as a rubber mallet or the side of a desk.
4. Hold the vibrating tuning fork close to the suspended ping pong ball.
5. Observe how the ball moves when it is touched by the vibrating tuning fork.

Ping Pong Ball vs Tuning Fork - Another Sound Wave Demo - Ed Reeves:

📄 Seeing sound vibrations - The Ogden Trust: https://www.ogdentrust.com/wp-content/uploads/2021/09/Purposeful-practical-seeing-sound-vibrations.pdf

• Test what happens when you strike the tuning fork with different amounts of force (lightly, medium, hard).
• Try changing the mass of the ping pong ball by taping small amounts of Blu Tack to it and observe how this affects its movement.
• Compare how balls of different materials (such as Styrofoam or cork) react to the tuning fork vibrations.

• Do not hit the tuning fork on hard surfaces like metal or stone, as this may damage it.
• Make sure the ping pong ball is suspended securely so it does not fly off.

• Why does the ping pong ball move when touched by the tuning fork? (Because the vibrating prongs transfer energy to the ball.)
• What happens if you strike the tuning fork harder? (It produces larger vibrations, causing a louder sound and greater ball movement.)
• Why does the ball eventually stop moving? (Because energy is lost to the air and friction, so the vibrations fade.)
• Why is a ping pong ball used instead of a tennis ball? (It is very light, so even small vibrations can move it.)
• How does the length of a tuning fork’s prongs affect its pitch? (Shorter prongs vibrate faster, producing higher-pitched sounds, while longer prongs vibrate slower, producing lower-pitched sounds.)