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Homework Help: Kinetic friction, i forgot

  1. Nov 25, 2004 #1
    here is the problem:

    a 0.215 kg metal rod carrying a current of 11.8 A glides on two horizontal rails 0.460 m apart. What vertical magnetic field is required to keep the rod moving at a constant speed if the coefficient of kinetic frictin between the rod and rails is .120?

    i forgot what kinetic friction is, and what the formula is..If i knew that i could easily solve tihs problem. I only have volume 2 of my physics book which doesnt go over this, and i learned this over a year ago and i forgot what it is..Can someone please refresh my memory? thanks
  2. jcsd
  3. Nov 25, 2004 #2
    Kinetic friction is given by:
    [tex]f_k = N\mu_k[/tex]
    Where N is the normal force and uK is the coefficient of kinetic friction.
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