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Homework Help: Angular Velocity and Angular Acceleration

  1. Mar 4, 2009 #1
    I feel really dumb, as this should be incredibly easy to figure out, but I keep getting the wrong answers. I am including the book's data so I can figure out how this needs to be done and then plug in my own values.

    1. The problem statement, all variables and given/known data

    Pilots can be tested for the stresses of flying high-speed jets in a whirling "human centrifuge," which takes 1.0 min to turn through 20 complete revolutions before reaching its final speed.

    What is its angular acceleration (assumed constant) (in rev/min^2) and its angular velocity in rpm?

    2. Relevant equations

    Code (Text):

    \theta (t) = \theta_0 +\omega_0t + \frac{1}{2}\alpha t^2  
    \omega (t) = \omega_0 + \alpha t.

    [b]3. The attempt at a solution[/b]

    I have tried finding the frequency and then multiplying it by 2\pi, but I don't get the right answer. The book's values are:
    Ang. Acc = 40 rev/min^2
    Ang. Vel = 40 rpm
  2. jcsd
  3. Mar 4, 2009 #2


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    Homework Helper

    i think it might have something to do with your units

    theta = (1/2).alpha.t^2

    you want to find alpha in rev/min^2
    so input theta in revolutions and t in mins to get the correct alpha
  4. Mar 4, 2009 #3
    I don't think I have a value for theta unless it is 2pi. Even then, that is in radians not revolutions per minute.
  5. Mar 4, 2009 #4
    Thanks LowlyPion, my answer for angular acceleration is correct and the concept is much more clear now. I'll let you know if I get angular velocity figured out, which should be easy from here.
  6. Mar 4, 2009 #5
    To find Angular velocity I multiply angular acceleration by time. Thanks for the help.
  7. Mar 4, 2009 #6
    I forget how to mark this as solved, also, does anyone know how to use direct LaTeX typesetting here?
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