Recent content by jebuss

the reason i asked was i was thinking about the upside down glass of water covered with a coaster or something, and wondering what the pressure of the air in the upturned glass was. i know the usual explanation is the gas expands slightly inside, but before that , is it just atmospheric in there?

so the cups reaction is equal to the mass of the covering only?

if the cup covering was totally rigid, wouldn't it be possible for all the atmospheric force to be support by the cups reaction? in which case, why would the gas inside the cup need to exert atmospheric pressure back on the covering.

something has happened, you've covered the top. the atmospheric pressure is caused by the weight of the fluid above it, so when you place a barrier there, that weight is partly taken by the glass itself. its seems like its got to be atmospheric , or the top would cave in, but i don't see how the...

well i sort of suspect it is atmospheric, but i was wondering about the mechanism for the transmission of the force through the paper or whatever it is, since in your P=pgh, you measure from the top of the column you have. is there any deforming of the paper, etc

Homework Statement If i covered the top of a cup with an airtight covering, what would be the pressure just below this covering, and how would it have come about?