Balloon on the Bottle - Results

Answers

Answer to question 1. Any answer is correct, as long as you wrote down what you thought would happen.
Answer to question 2. The balloon on the bottle was floppy at first. When you hold the bottle under the hot water tap, the balloon inflates somewhat.
Answer to question 3. Any answer is correct, as long as you wrote down what you thought would happen. The hot water from the tap heats up the bottle. The plastic gets warmer, and so does the air inside the bottle. Air expands when it heats up. When the air gets hot, it does not fit inside the bottle any more. When that happens, the air is pushed into the balloon. This means that the balloon is inflated by the heated air from the bottle.

Extra Explanation

Air presses in all directions. This is called air pressure. Normal air pressure is about the same as the weight of 1 kilogram per square centimetre.

In this test, there is air inside the bottle. Holding the bottle under the hot water tap heats up the air. When the air in the bottle gets warmer, the air pressure inside the bottle increases. The air tries to take up more space, so part of the air flows out of the bottle and inflates the balloon.

If you take the bottle out of the hot water, the air will cool off again. The balloon will shrink again too. Once the air has gone all the way back to room temperature, the balloon will be floppy again.