Re: What is the scientific reason that people slip while walking on wet or icy

    The question is, basically, why is a sidewalk (for instance) slippery 
with water or ice on it?
    The reasons are two.
    First, friction is less between the bottom of the shoe and the sidewalk 
with a layer of water than it would be between the shoe and a dry sidewalk.
    Second, ice is an interesting substance which has a raised freezing 
temperature under increased pressure, so when you walk on the ice and the 
pressure on the ice is increased a thin layer of ice melts and becomes liquid 
water, so, again, the friction is reduced.  When you are on ice the friction is 
even less than on just a wet sidewalk because the still-frozen surface of the 
ice is very smooth.
    You can find more information about this by looking at books that 
describe the "triple point" of water or the characteristics of ice, and also 
books that discuss friction.  Try looking at some of the sources available at 
the MadSci network, but don't stop there!



John Link

   MadSci Scientist and Administrator