Naked Science Forum
General Science => General Science => Topic started by: Anastasia.fr.1 on 02/08/2007 10:42:50
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first i got a beaker and filed it up with hot water left it for about 4 secands then tiped it out then quicly put my hand on the beaker then left it on my hand for about 2 minits then gently lifted my hand up andthe beaker was stuck to my hand.
why did this happen [?]
from anastasia
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi154.photobucket.com%2Falbums%2Fs262%2Fpf0604%2FImage020-1.jpg&hash=69c4928ac2ffc971ca457b6ff90f5774)
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What you experience is that the air pressure decreases as the air left in the beaker is cooling. But that means that initialy you had to push rather hard so that there is no leakage between your skin and the rim of the beaker.
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Great Job Anastasia! I love it! I have to go try it..
Eric is that kind of the same principal as when you have boiled water and you put a lid on the pan and turn it off. as the pan and water cools, the lid is basically vacuumed to the top and needs to have the suction broke to release the lid? Is this like Anastasia's experiment here except with her hand?
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i love your experiments anastasia!
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Great Job Anastasia! I love it! I have to go try it..
Eric is that kind of the same principal as when you have boiled water and you put a lid on the pan and turn it off. as the pan and water cools, the lid is basically vacuumed to the top and needs to have the suction broke to release the lid? Is this like Anastasia's experiment here except with her hand?
It is indeed, and a little easier as a demonstration.
Actually, the first steam engines worked along this principle : the cylinder was filled with steam, then cooled by spraying cold water on it. This created a relative vacuum, and the atmospheric pressure moved the piston.
See http://en.wikipedia.org/wiki/Steam_engine#Vacuum_engines