From: Geoff Ruth (gruth@uclink4.berkeley.edu)
Date: Sat Nov 11 2000 - 19:08:19 PST
Message-Id: <v04011700b633b9ca0b2a@[128.32.190.180]> Date: Sat, 11 Nov 2000 19:08:19 -0800 From: Geoff Ruth <gruth@uclink4.berkeley.edu> Subject: Re: pinhole Car on Ice
Paul,
I don't understand the explanation of why ice skates slip across ice. If
ice skates slip (ie hyave reduced friction) why doesn't everything slip
across ice? The top 'liquid' layers of ice seem like they should allow
anything to slide.
-Geoff
>Ice is frictionless because the top twenty layers of water molecules in
>solid ice behave like a liquid in their structure and properties. These
>molecules easily slide over each other. So even if the rubber of the tire
>sticks to the top layer of water molecules, these molecules slide over the
>ones below just as they would in a liquid.
>
>(This is the new theory of how ice skaters skate too, the old myth that the
>pressure of the skate blade melts the ice is now known to be wrong. Water
>ice will melt under pressure but the pressure at the skate blade is too low
>by more than an order of magnitude.)
>
>Paul D
>
>Paul "But it is more complicated than that!" Doherty,
>Senior Staff Scientist, The Exploratorium.
>pauld@exploratorium.edu, www.exo.net/~pauld
>
>
>
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