How does a submarine work?

Using just a penlid, some plasticine and a lemonade bottle, to find out what principle submarines work on.

What you need

	A large lemonade bottle full of water		Some plasticine or blue tack
	A pen lid

 

It also works with a ketchup packet weighted with a paperclip instead of the pen lid

 

What to Do

1- If you are using the penlid, use some plasticine to block the hole in the top, then add plasticine to the bottom of the lid until it just floats

2- Fill the bottle up to the top

3- Float the lid or sachet in the bottle.

4- Put the lid on the bottle

5- SQUEEEZE

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What may Happen

When you squeeze the bottle you should find that the diver ( the penlid / sachet ) sinks and then when you stop squeezing it should float again. You should be able to repeat this as often as you like.