Re: misconception re ice melting under skates

[Leigh Palmer <palmer@sfu.ca>]

> According to Clifford E Swartz, who talked about the ice skating
> misconception at our regional AAPT meeting (two year ago?) a layer
> of loose molecules always exists at the interface. This
> provides lubrication. I do not know why. But I did convice myself
> about the myth by performing the "wire through a block of ice" experiment
> outdoor when the temperature was below freezing. The loaded wire remained
> on top of my block outdoor but was cutting through the wire indoor. This
> shows that melting indoor is due to the delivery of caloric to ice via
> wires and not to preesure. Or use the triple point data for water to
> show that the pressure is not large enough to lower the temperaturenificant
> significantely.

You misinterpret the result. Doing the experiment indoors assures
that the ice will be at the melting point. Pressure melting occurs
at the melting point at a relatively low pressure. A reasonable
way to test your hypothesis is to take wires of different thermal
conductivities and identical diameters (say stainless steel and
copper) and time their cutting. One would expect the times to
differ by the same proportion as their thermal conductivities if
your hypothesis is correct.

Leigh