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Homework Help: Compact disk angular acceleration

  1. May 6, 2012 #1
    1. The problem statement, all variables and given/known data

    A compact disc speeds from rest to 5200 rpms in 620 rad. Diameter is 5.0cm
    -how many revolutions did it make in this time
    -what is the angular acceleration in rad/s^2
    -how long does ti take to reach this speed

    2. Relevant equations

    3. The attempt at a solution
    i was able to find the first part by
    620(180/π) = 35523 dividing that by 360 and getting 99 revolutions

    for the last 2, i am completely lost to where i even begin solving them.

    thank you..
  2. jcsd
  3. May 6, 2012 #2


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    Science Advisor
    Homework Helper

    welcome to pf!

    hi jkhays! welcome to pf! :smile:

    you can use the usual constant acceleration equations, with angular acceleration velocity and displacement instead of ordinary (linear) acceleration velocity and displacement :wink:
  4. May 6, 2012 #3
    You know ω initial and ω final, and Δθ. You can solve for angular acceleration using one of the kinematics equations for constant acceleration. Once you have alpha you can solve for t.
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