From: nancy@genie.slhs.udel.edu (Nancy Lebovitz)
Subject: Re: Hot water
Organization: UDel, School of Life & Health Sciences
Date: Sat, 25 Jul 1992 15:18:56 GMT

In article <14qm53INNofn@agate.berkeley.edu> emarkp@ocf.berkeley.edu (E. Mark Ping) writes:
>In article <1992Jul22.095347.16@antioc.antioch.edu> mbaya@antioc.antioch.edu writes:
>>In article <59140@mimsy.umd.edu>, tms@cs.umd.edu (Tom Swiss (not Swift, not Suiss, Swiss!)) writes:

[tenuous connection to martial arts deleted]

>>and is it also true that Hot/boiling water will freeze faster than
>>cold water? I know I heard this somewhere a long time ago. Why does it
>>do this?
>
>  Of course not.  Not if both samples have the same number of molecules and
>the same amount of surface area exposed to the environment.
>
>  Take two samples of water with equal number of molecules in the sample
>(with equal impurities).  Say sample X is warmer than sample Y (both in the
>liquid phase for the more anal of you out there :-)
>
>  Sample X will change temperature more quickly in a refrigerator (i.e.
>dT/dt is more negative), however when the temperature of X reaches the
>initial temperature of Y, it will take an additional amount of time to
>freeze equal to the *total* amount of time it takes Y to freeze.  At least
>in theory, with the above conditions holding.
>
>  In practice however, this isn't always the case.  Sample X is more likely
>to be the same *volume* as sample Y.  Since sample X has a lower density, it
>also has fewer molecules which need to be cooled.  Also, the material in
>which one is cooling the water may have some effect on the time -- i.e. a
>metal container would allow the head in the warmer sample to disperse over a
>greater surface area, allowing it to cool faster, etc.

There was a long thread about this on alt.folklore.science, and
the conclusion was that, if the containers are uncovered, the hot water
will freeze faster because some of it will evaporate so that there's less
of it to freeze. (It takes the loss of a lot of energy/molecule to
get water to freeze.) 

This can be tested by weighing the ice cubes when you're done. On the
other hand, no one in afs (that I know of) brought up the point that
equal volumes of hot and cold water would start out with different
weights.

Just to have a little martial arts content, here's the story of the
white belt who led with his face.  Once upon a time, a white belt
entered a Kenpo tournament, where anyone who hit their opponent in
the face would be disqualified. 

The white belt had the habit of fighting hunched forward with his face
sticking out. It represented a very tempting target, and his opponents
kept hitting him there and getting disqualified until none of them 
were left. The white belt won the prize in his division and never
took another class. 

Let me know if you think of a moral.

                              Nancy Lebovitz
                              calligraphic button catalogue availible by
                                      email (170K)
                              nancy@genie.slhs.udel.edu

I guess we were all guilty. We all shot him, we all skinned him, and we
all got a complimentary bumper sticker that said, "I killed Bob". 
Newsgroups: rec.martial-arts