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Homework Help: Particle sliding on a track (cons. of energy problem)

  1. Oct 15, 2008 #1
    A particle can slide along a track with elevated ends and a flat central part, as shown in Figure 8-53. The flat part has length L = 40 cm. The curved portions of the track are frictionless, but for the flat part the coefficient of kinetic friction is µk = 0.32. The particle is released from rest at point A, which is a height h = L/2. How far from the left edge of the flat does the particle finally stop?

    08_60.gif

    I set this equation:

    mgh = μmgd

    d = h/μ

    d = 20/.32

    d = 62.5 cm

    Because the answer > L, I subtracted 40 cm from it and got 22.5 cm as the answer (I'm supposed to give it in cm). But it won't accept my answer. What did I do wrong?
     
  2. jcsd
  3. Oct 15, 2008 #2
    You did all the math right to determine distance - the particle will move 62.5 cm on the flat surface before coming to a stop. Now think about the direction it is traveling and where that is in relation to the left edge of the flat surface.
     
  4. Oct 15, 2008 #3
    Oh, I see.

    Thanks a lot for saving me from losing a point. :)
     
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