What you need:
- A small balloon
- A one-litre plastic bottle
- A drawing pin Water
What to do:
1. Insert the balloon into the bottle. Fold the mouth of the balloon over the mouth of the bottle.
2. Now, blow the balloon. Does it work?
3. Poke a hole into the bottom of the bottle using the drawing pin.
4. Try blowing up the balloon again. What happens?
5. While the balloon is filled with air, cover the hole at the bottom of the bottle. Leave the mouth of the bottle open. What do you see?
6. Now, release the hole and observe what happens to the balloon.
What happens:
When there no hole in the bottom of the bottle and you try to blow up the balloon, it does not inflate. After the hole is made, it is easy to inflate the balloon.
When you place your finger on the hole, leaving the mouth of the bottle open, the balloon stays inflated! Tricky, huh? Once you remove your finger, the balloon deflates.
Why?
An empty bottle isn’t really empty. It has air in it.
When you fold the balloon over the mouth of the bottle, you seal the air in. There is nowhere for the air to go. When you try to blow up the balloon, it doesn’t inflate because the bottle is already filled with air. It’s a great way to show how air occupies space. When you poke a hole into the bottom of the bottle, air can escape from the bottom of the bottle. This gives the balloon space to expand and fill with air
When you plug the hole, the balloon stays inflated because the air pressure inside the balloon is higher than the air pressure in the bottle. Simply put, it means that the air molecules inside the balloon are pushing harder against its walls than the air molecules inside the bottle.
When you unplug t he hole air rushes into the bottle. Now, there is enough air in the bottle to push against the balloon from the outside. So the air inside the balloon is pushed out and the balloon shrinks.
Picture Credit : Google
