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Homework Help: Rotational Motion About a Fixed Axis , NEED HELp :\

  1. Mar 21, 2008 #1
    1. The problem statement, all variables and given/known data

    A wheel of diameter of .68m roll without slipping. A point at the top of the wheel moves witha tangential speed of 5.4m/s. Whaat speed is the axle of the wheel moving? What is the angular speed of the wheel?

    How would i approach to do this problem, what equations would i need to use ?
  2. jcsd
  3. Mar 21, 2008 #2
    ok for speed of axle i took .5 * 5.4 to get 2.7m/s

    and for angular speed of wheel i took 5.4mn/s * .34m to get 15.9 rad/s

    am i correct ?
  4. Mar 21, 2008 #3


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    Hi keylostman!

    Are you the same person as th3plan?

    Why have you posted the same problem twice?

    Your speed is right, but your angular speed is not.

    Angular speed = speed/radius, where speed means speed relative to the centre.

    You can either take the centre to be the axle - so the radius is .34, but you have to subtract the axle speed - or you can take the centre to be the (stationary) point of contact - so the radius is .68.
  5. Mar 21, 2008 #4
    so i take 5.4-2.7 ti get 2.7 m/s and multiply by .34m the radius to get .918 rad/s ?
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