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Homework Help: Please Help Dynamics In A Circle

  1. Oct 26, 2007 #1
    1. The problem statement, all variables and given/known data
    A penny of mass 3.10g rests on a small 20.0g block supported by a spinning disk. The coefficients of friciton between block and disk are .750(static) and 0.640(kinetic) while those for the penny and block are 0.520(static) and .450(kinetic). What is the maximum rate of rotation in revolutions per minute that the dsk can have, without the block or penny sliding on the disk?


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 26, 2007 #2

    Doc Al

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    Staff: Mentor

    What force prevents the penny from sliding?
     
  4. Oct 26, 2007 #3
    static friction
     
  5. Oct 26, 2007 #4
    I think I can solve this problem now thanks
     
  6. Oct 26, 2007 #5

    Doc Al

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    Staff: Mentor

    Right. So what's the maximum force that static friction can exert on each object?
     
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