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Homework Help: Angular Acceleration and wheel revolution

  1. Feb 19, 2007 #1
    1. The problem statement, all variables and given/known data

    A wheel accelerates from rest to 59 rad/s at a rate of 29 rad/s². How many revolutions the wheel turned while accelerating?


    2. Relevant equations


    3. The attempt at a solution

    I'm confused, I suck at this kind of problem. I got change in angular velocity which would be 59rad/s, and I got that the angular acceleration would be 29 rad/s². What equation relates all three? All equations I know relate them using time, but I got no time there.
     
  2. jcsd
  3. Feb 19, 2007 #2

    Dick

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    The equation you are looking for is an EXACT analog of the equation for linear motion, s=(1/2)*a*t^2. Does that help?
     
  4. Feb 19, 2007 #3
    Not really. See that would translate into angular motion as this:

    Angular Displacement = 1/2*Angular Acceleration*Time²

    And since I got no time, that equation is useless. I need an equation that somehow relates ONLY angular displacement to angular velocity and angular acceleration

    Unless I'm missing a way to get the time from the given data....
     
  5. Feb 19, 2007 #4

    Dick

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    Well, you know the initial velocity, the final velocity and the acceleration. Could that give you a time?
     
  6. Feb 19, 2007 #5
    ...could it?
     
  7. Feb 19, 2007 #6

    Dick

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    I would say that if I accelerate from 0 to 10 m/sec at an acceleration of 10 m/sec^2, then the time it takes is 1 sec.
     
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