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Re: [Phys-l] Wire through ice experiment



Pressure-induced melting of ice has been used to explain the
wire-through-ice demonstration as well as the low friction of ice skating.
It is the wrong explanation in both cases, and this has been known for a
long time. The misconception is taking a very long time to go away.

The wire-through-ice demo is a thermal conductivity example, and ice skating
is a surface-layer of water example. I remember discussions about this when
I was in graduate school over 30 years ago. Even then the physical chemists
and chemical physicists (which I am) knew that pressure was not doing it.
For the ice-skating case, a good article appeared in Physics Today in the
December 2005 issue.

I've been involved in experiments in walk-in refrigerators (cold rooms) at
various temperatures showing that the wire does not go through the ice if
the ambient temperature is zero Celsius or lower. Although pressure-induced
melting is theoretically possible, the ambient temperature would have to be
controlled very accurately in order to be convinced that pressure-induced
melting-point depression was the cause of the wire going through the ice.
Since the depression is hundredths of a degree, the wire won't go through
the ice at all if the ambient temperature is more than a few hundredths
below zero Celsius. If the ambient temperature is a bit above zero, then
thermal conductivity from the ambient air through the wire is the primary
cause of the melting.

Therefore, the study conducted by the student in Finland may have been a fun
and educational project for the student, but it is not new science.


Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
1 University Drive
Bluffton, OH 45817
419.358.3270
edmiston@bluffton.edu