From: utzoo!decvax!decwrl!sun!megatest!fortune!dsd!atd!avsdS:nelson
Newsgroups: net.physics
Title: Re: Tea Bags
Article-I.D.: avsdS.257
Posted: Fri Dec 17 09:01:32 1982
Received: Thu Dec 23 23:29:26 1982

Thermal expansion of air inside the bag is obviously the reason it inflates.
I don't know where you got an "expansion coefficient" for air, but such
numbers apply to solids and liquids, not gases. The gas law is PV = nRT,
which means that when the temperature doubles so does the volume (or
pressure). Undoubtedly both the pressure and volume increase in the tea
bag. The water film that covers the bag after it gets wet makes it much
less permeable; coarser mesh bags would deflate easier (when you abuse
them with a spoon to make them stay down).

	Glenn Nelson, Ampex, Redwood City