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Homework Help: Rolling Friction Problem

  1. Feb 18, 2009 #1
    1. The problem statement, all variables and given/known data

    Two bicycle tires are set rolling with the same initial speed of 3.60 m/s along a long, straight road, and the distance each travels before its speed is reduced by half is measured. One tire is inflated to a pressure of 40 psi and goes 18.7m ; the other is at 105 psi and goes 93.3m . Assume that the net horizontal force is due to rolling friction only.

    What is the coefficient of rolling friction for the tire under low pressure?

    2. Relevant equations

    Vf^2=Vi^2 +2ax
    Ur=a/g ?? (Ur= coefficient of rolling friction

    3. The attempt at a solution

    1st Tire:
    -(3.60)^2/(2*18.7) = a = -.3465


    This is wrong, but I honestly have no idea what to do. Help is GREATLY appreciated! :)
  2. jcsd
  3. Feb 18, 2009 #2


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    Homework Helper

    Welcome to PF.

    I would start off by recalculating your expression for tire 1.

    Reread the problem statement. The distance of 18.7 is when |v| = 1/2*|Vo|, not when it goes to 0.
  4. Feb 18, 2009 #3
    ahh, missed that little fact. Got the right answer now :)
    Thank you!
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