In school I am doing a science experiment. My science
experiment is:
"Dip a ten pence coin in a cup of water. Put the
ten pence coin on top of a bottle. Then put your hands around the
bottle. Your hands warm the colder air in the bottle. The air expands
when it gets hotter, and this pushes the coin up."
Thanks Emma Yr 4
Please can you tell me why I need to dip the coin
in a cup of water?
This is all about heating up the air in the bottle
and it forcing the coin up. The surface of a coin is not flat (there
are bumps and such like where the queen's head is). Without water
the air would expand and escape through the gaps. The coin is wet
when you place it on the top of the bottle and the water will sit
between the coin and the bottle making a seal. When the air expands
it forces the coin up as it cannot escape through the seal.
Do you know the property of water that causes it
to do this? That makes water stick to things? Now there is something
else for you to find out. Let me know when you find out.
Greg
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