a myth about ice skating

[kowalskil@alpha.montclair.edu]

On 1/2/97 Tom Gordon (a different discussion group) wrote:

> I am reminded that as a kid I had once gone up to VanCourlandt Park early 
> on a V-E-R-Y cold Saturday morning in January, with borrowed skates. Some 
> big guys were there before us and were skating, but when we attempted to  
> join them, it was like trying to skate on concrete.

I detect a hint that "big guys created more pressure below their blades
producing a layer of water. Little guys were not heavy enough for this." 
Or are you simply saying they were stronger?
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It is true that skating at very low temperatures, such as -20 C and below, 
is more difficulr than at -5 C or so. How can this be interpreted? Does the 
coefficient of friction of steel on ice (without a layer of water) increase 
when the temperature drops? Or do we experience less and less lubrication 
due to less water produce from friction? What kind of experiment can help 
to clarify this in an introductory physics course? 

I take it for granted that presence of water below the skating blades
is due to friction. It can not possibly be due the lowering of melting 
temperature. Why? Because blades form grooves and the pressure is never 
large enough to lower the melting point significantely (always less
than 0.1 K or so).
                   Ludwik Kowalski        kowalskiL@alpha.montclair.edu
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