Re: pinhole Car on Ice

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From: Paul Doherty (pauld@exploratorium.edu)
Date: Sat Nov 11 2000 - 16:55:18 PST 

Message-Id: <l031107e1b63399ccafec@[192.174.2.173]>
Date: Sat, 11 Nov 2000 16:55:18 -0800
From: Paul Doherty <pauld@exploratorium.edu>
Subject: Re: pinhole Car on Ice

Hi Jhumki

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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