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Homework Help: Hoop rolling down incline

  1. Oct 21, 2012 #1
    This a question from my 131 "masteringphysics.com" hw.

    A cylindrical hoop has radius 10.0 cm and mass 0.550 kg. It rolls from rest a distance of 5.70 m along a board which is tipped up by an angle 18.0 degrees from horizontal. Regard the hoop as being much thinner (in the radial direction) than its radius.

    Parts A and B wanted me to find the total kinetic energy and velocity at the base of the incline, I already did these. KE = 9.49 J and v=4.15 m/s

    However part C wants me to:
    What minimum value must the coefficient of static friction have if the hoop is to roll without slipping?
    I have no idea how to approach this part.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 21, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Start by drawing a free body diagram showing all forces acting on the hoop. Then apply Newton's 2nd law for both rotation and translation.
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