Pitch and Spin

Sound

Things You Will Need
• Index card, playing card, or small piece of cardboard
• Bicycle wheel
• Clothespin or masking tape

   

   

   

Do This

1. Hold the edge of the card or cardboard against the bicycle wheel spokes OR attach the card or cardboard to the wheel strut so that the edge is against the wheel spokes.
2. Revolve the wheel slowly and then gradually faster and faster.
3. Observe the difference in the sound at slow and fast speeds.

What Should Have Happened

The faster you spin the bicycle wheel, the higher the sound from the card becomes. The highness or lowness of a particular sound is called the pitch. Pitch depends on the number of vibrations that occur per second. The more vibrations per second, the higher the pitch.