Balloon Blowing

Balloon Blowing, Monday, 3rd March, 2008

This is an ordinary balloon that we can easily blow up.

If we put it inside a bottle it doesn’t blow up so easily. Why not?

When we put the balloon in the bottle there is air in the bottle already. We can’t blow up the balloon without moving the air that is in the bottle already, and there is nowhere else for this air to go. It is impossible to blow up the balloon.
If we cut the end off the bottle, now the air can be pushed out of the way and we can blow up the balloon.