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Homework Help: Magnetic Force Problem

  1. Jul 24, 2006 #1
    The two conducting rails in the drawing are tilted upwards so they make an angle of 30.0° with respect to the ground. The vertical magnetic field has a magnitude of 0.055 T. The 0.22 kg aluminum rod (length = 1.6 m) slides without friction down the rails at a constant velocity. How much current flows through the bar?
    p21-35.gif


    I know the formula to use is Fb = ILBsin0

    What isn't given plainly is the Magnetic force. I tried to use F= m x a to find this force, but there is no acceleration. I tried plugging in 1, giving the F a value of .22kg and that didn't work. Then I tried dividing it by two since there are two rails, still didn't work.

    What am I missing?
     
  2. jcsd
  3. Jul 24, 2006 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Don't forget that the rod has weight and is in equilibrium.
     
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