1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Circular Motion and Static Friction

  1. Oct 20, 2009 #1
    1. The problem statement, all variables and given/known data

    A small metal cylinder of mass m=0.20 kg sits on a rotating turntable. The coefficient of static friction between the metal cylinder and the turntable is us=.08. The cylinder is located 0.15m from the center of the turntable. Find the maximum speed that the cylinder can have without skidding. Acceleration due to gravity equal 9.81 m/s^2.

    2. Relevant equations

    Fmax=us x normal force

    3. The attempt at a solution
    Fmax=.08 x 9.81


    Tangenitial acceleration equals zero so.

    V=.767 m/s

    but i dont think this is correct. What am i doing wrong?

    Any help is appreciated.
  2. jcsd
  3. Oct 20, 2009 #2


    User Avatar
    Homework Helper

    Likely you just forgot the mass when you did
    Fmax=μmg = .08 x 9.81
    Just a suggestion from an old timer - it is often helpful to separate the big picture from the details. I would begin this problem by writing the slipping condition:
    Fc = Ff
    then fill in the details with
    m*v^2/r = μmg
    cancel the m's and solve for v. Put in the numbers only in the last step. I can tell you that this kind of approach will serve you well when the problems get more complex.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook