windshield fluid sprayer

[Brett Dikeman]

At 4:17 PM -0500 11/29/01, Robert Myers wrote:
>--
>Bullpucky, Phil.  Absolute nonsense.  The colder sample freezes
>first.  There is simply no way around thermodynamics.

There's simply no way around thermodynamics, but there's nothing
simple about thermodynamics when it comes to something wacky like
this :-)  You're assuming temperature is the only factor.

>   The hot sample must
>first lose heat to reach the starting temperature of the colder
>sample.  This takes time during which the colder sample has reached a lower
>temperature and/or has started already to freeze.
>

There are a variety of effects at work, and some conditions to be
met, but the near-boiling container will freeze first if both are
a)uncovered and b)"outside"(I suspect some of the effects below would
not properly work given a finite amount of air easily saturated with
moisture) then:

a)the hot water container will loose a substantial amount of heat and
mass due to evaporation(phase change=massive energy loss)
b)a skin of ice will form over the cooler container insulating it
c)the hotter water will get supercooled(Huw mentioned this) so it
will drop in temperature faster


Cover both containers and its a different ball game; there's no loss
due to evaporation nor phase change, but you still have the
supercooling effect.

B
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