A whistle is a “wind” instrument that can only make one note, right? Students will be intrigued as you produce a symphony of sounds with a single whistle. Sound waves travel faster in less dense gases, and therefore produce higher frequency (pitch) sound. In this demonstration, three balloons are filled with separate gases of differing densities, clamped off, and attached to separate whistles. Release the clamps on the balloons one by one and listed to the startlingly wide range of pitches emitted by the simple whistle. Teacher Demonstration notes, reproducible student worksheets and all the specialized materials necessary to perform the demonstration at least seven times each are included.
Concepts: Density of gases, speed of sound; pitch
Time Required: 20 minutes
Note: Sources of gases are required but not provided.