- 1 Balloon
- Blow up the balloon so that it is filled with air
- Hold the balloon up to your ear.
- Lightly tap the other side of the balloon with your finger. Can you hear the sound well? Can you feel the vibrations?
- Now let go of the balloon. Which way does the air escape? Which direction does the balloon move in?
How it Works:
When you blow into the balloon you are pushing air molecules into the balloon. They are forced into a small area so are very close together. These circumstances allow the air molecules to carry the sound waves better. That is why you can hear the tapping so easily. It’s as if you built a speaker.
- Add a mini marshmallows to the balloon. Does it muffle the sound? Does it sound the same?
- If you have access to a helium tank, fill the balloon up with that instead. Is helium a better conductor of sound then the air that you pushed into the balloon?
- Can you hear different pitches based on how big or small the balloon is? Give it a try!