NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/physics/21857

Internet Message Format | 1992-12-29 | 1.7 KB

Path: sparky!uunet!cs.utexas.edu!tamsun.tamu.edu!venus.tamu.edu!dwr2560
From: [e-mail] (RING, DAVID WAYNE)
Newsgroups: sci.physics
Subject: Re: bubble in container
Date: 29 Dec 1992 15:37 CST
Organization: Texas A&M University, Academic Computing Services
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[e-mail] (Daniel Seeman) writes...
>But the sinking part is really not central to the problem.  One could just
>anchor the bubble to the bottom of the container, fill the container with water,
>and close it.  With the help of a friendly gremlin (that lives inside the con-
>tainer, of course ;-) the bubble would get bursted.   After the system returns
>to equilibrium, what are the differences between the initial and final pressures
>in the container?

Let's see if we can make the paradox a little clearer. Start with the
sealed jar of incompressible fluid. Our gremlin builds a small sphere
near the bottom of the container which naturally will contain a bit of
fluid. Then through a tube he drains the sphere and fills it with
air at the local fluid pressure. He then breaks the sphere and lets the
bubble rise to the top, increasing the pressure everywhere. When the
bubble reaches the top he reverses the procedure, surrounding it with
a sphere, filling it with fluid, and breaking the sphere.

The final state has the same fluid in the same volume but different
pressure. In fact one can repeat the procedure ad infinitum to get
as high a pressure as one likes.

:-)

Dave Ring
[e-mail]