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Friction coefficient is greater than 1 explanation

  1. Oct 4, 2011 #1
    The data came from my lab involving friction between wooden block with metal weight on it and a metal table. The wooden block is moved from rest and the force is measured using a force meter and Logger pro.

    1. The problem statement, all variables and given/known data

    Force of peak static friction = 23.285N. Normal force is 20.567N
    u=F/N=1.132

    2. Relevant equations

    Why is the coefficient of friction greater than 1? Several groups in my class also had similar results with u>1. Why is that?

    My guess is that there are some very small substance or agent between the wood block and table surface that is sticky and adds to friction force, or maybe there is magnetic force because there was a metal weight put on top of the wooden block to add more mass. Are my explanations plausible? Is there a better explanation?
     
  2. jcsd
  3. Oct 4, 2011 #2

    SammyS

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    There is nothing that says the coefficient of friction can't be greater than 1 .
     
  4. Oct 4, 2011 #3
    The only real "no no" is a kinetic friction coefficient larger than that of static.

    1.132 is acceptable, if it were 1.8 or something then I'd worry.
     
  5. Oct 4, 2011 #4
    Ok cool. So there is no absolute max? In wikipedia it says a rubber tire on concrete has u around 1.7 so how much higher does coefficient of friction go?
     
  6. Oct 4, 2011 #5
    I would think the limit would be based off the materials that exist in the universe, no mathematical limit.

    For example, syrup running down a kitchen wall. That would be an enormous coefficient.
     
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