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Homework Help: More help finding frictional force.

  1. Nov 1, 2006 #1
    I really am not getting this physics stuff...again I thought I had this one figured out but it doesn't seem to be right.
    So the question...
    A 49.2 kg car is moving at 12.6 m/s around a horizontal curve whose radius is 31.3 m. What is the magnitude of the fictional force required to keep the car from sliding?

    and this is what I did..
    I found my net force for x and y
    Fy = may
    Fy = 0
    N- W = 0
    N = mg

    Fx = max
    fs = max
    u x N = m(v^2/r)

    so then I substituted in my N and got
    u x mg = m(v^2/r)

    and I solved for u (frictional force...I'm just using u for the term)

    u x (49.2kg)(9.81m/s^2) = (49.2kg)(12.6^2/31.3m)

    and it works out to be 0.517 and the computer is telling me I'm wrong once again. so I must be wrong.
  2. jcsd
  3. Nov 1, 2006 #2


    User Avatar
    Science Advisor
    Homework Helper

    The question does not ask you to find μ. It asks you for the frictional force.
  4. Nov 2, 2006 #3
    Thank you! I have some serious problems with reading these things wrong.
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