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Need help why did the water increased the friction?

  1. Nov 2, 2009 #1
    need help!! why did the water increased the friction??

    I did an experiment where I pulled a shoe using a Newton meter on wet board and it was harder to pull the shoe than when it was dry.

    The more water I added on the board the harder it was to pull the shoe!

    Can someone explain why because logically there should be less friction on water???
     
  2. jcsd
  3. Nov 2, 2009 #2
    Re: need help!! why did the water increased the friction??

    In short, because friction was not the only force at work once you had added the water.

    Lets say you use a suction cup to attach your cars sat-nav to the windscreen. We all know that the cup will work better when its wet. The reason it works better is because the water forms a bond with the surface that is much more air tight than simply leaving it up to the solid cup alone. This is because water molecules are able to plug the gaps that (mostly) static solid molecules can't.

    So when you pulled you shoe along, the water acted to create a vacuum effect between the surface of the table and the shoe, which bound the two together. This would, of course, result in it being much harder to pull the shoe.
     
  4. Nov 2, 2009 #3
    Re: need help!! why did the water increased the friction??

    thanks a lot

    I understand better now
     
  5. Nov 3, 2009 #4
    Re: need help!! why did the water increased the friction??

    sounds like a pretty good shoe design to me!
     
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