Now for some fun! We know that air takes up space. If there is more air in a smaller space, the air is at a higher pressure, and it wants to go to go somewhere with lower pressure so that the air molecules don't bump into each other as much. Can we use this to make a banana launcher? You bet!
What you need:
- A drinking straw
- One stick. The stick should just barely fit into the the straw with no large gaps in between the stick and the walls of the straw.
- Some water
- A banana (peeled)
What you do:
- Push one end of the straw into the banana and pull it back out so that about one inch of banana gets stuck in the end of the straw.
- Dip the stick in the water, then put the end of the stick into the straw.
- Aim your straw launcher. Make sure that you are outside; bananas can get messy!
- Quickly push the stick all the way through the straw. If the wet stick makes a good seal with the straw, the banana will fly out without the stick even touching it!
What happened?
Inside the straw, there is a lot of air. The banana sealed off one end and the stick sealed off the other so that no air could escape. But when you pushed the stick into the straw, the air inside was compressed into a smaller space, so it had higher pressure. The air outside the straw has lower pressure, so the higher pressure air inside the straw wanted to get out. The only way for it to do this was to push the banana out!
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