Hot Air Balloon / The direction of hot air

Equipment and ingredients:

empty plastic bottle without the cap.
balloon.
bowl (large enough to put the bottle in, at least up to 2/3 of it) with hot water.
another bowl (large enough to put the bottle in, at least up to 2/3 of it) with cold water (put some ice in it).

The Experiment:

Put the balloon on the bottle's opened top.
First put the bottle inside the hot water vessel
what happened?
Take the bottle out and put it I cold water,
what happened now?

Scientific explanation:

The bottle is not really empty, it has air in it of course.
When you put the bottle in hot water, you get hot air in it,
when you take it out and put it in cold water you get cold air
in it.

Hot air particles have more energy and that’s way they tend
to move more rapidly, so the vacuum space is becoming
bigger, and at the end they move up. Up into the balloon that is growing with time.

The cold water takes the air energy, and the particles are
moving slower and tend to stay in the bottle. We can see it in
the shrinking balloon.

Dorith's experiments:

All my scientific experiments, I bring you here, are home made, for adults and children as well, to see and also to show (Children can do it in front of their friends). They are simple and can be done with simple stuff everybody have at home.

Hot Air Balloon Experiment