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: Turntable Friction Problem

  1. Nov 3, 2004 #1
    The coefficient of friction between a certain brass block and a large revolving turntable is µ = 0.26. How far from the axis of rotation can the block be placed before it slides off the turntable if it is rotating at 33 1/3 rev/min?

    :confused: :yuck: :frown: :grumpy: :surprised :rofl:
    Last edited by a moderator: Nov 3, 2004
  2. jcsd
  3. Nov 3, 2004 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Consider that it is friction that supplies the centripetal force.
  4. Nov 3, 2004 #3
    As long as the force that is needed to overcome friction is larger than the centripetal force the block will not move.

    [tex]F_{friction} = F_z \mu = mg\mu[/tex]
    [tex]F_{centripetal} = \frac{mv^2}{r}[/tex]

    so you can move the block from the axis of rotation until these are equal, and when they are equal this holds:
    [tex]mg\mu = \frac{mv^2}{r} \Leftrightarrow g\mu = \frac{v^2}{r}[/tex]
    and using [itex]v = r*v_{rotational}[/itex] you can solve this
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook