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Constant Angular Acceleration of a wheel

  1. Oct 30, 2006 #1
    Starting from rest at t = 0 s, a wheel undergoes a constant angular acceleration. When t = 1.9 s, the angular velocity of the wheel is 6.2 rad/s. The acceleration continues until t = 15 s, when the acceleration abruptly changes to 0 rad/s2. Through what angle does the wheel rotate in the interval t = 0 s to t = 47 s?

    okay.....there are too many times here..what am i supposed to do for the acceleration after 25sec...to 46secs? i don't know what acceleration to to use to find the angular velocity from 25 to 46secs, to take the total velocity and find the angular displacement.
  2. jcsd
  3. Oct 30, 2006 #2


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    Draw a graph, it may help. Since angular acceleration is constant, you know that angular velocity must be a linear function, whose slope you know from the first information given in the problem. The slope is enough to determine the angular acceleration.
  4. Oct 30, 2006 #3


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    Split this question up into two phases;

    Phase One:Constant Acceleration

    From t=0 to t=15, you have a constant angular acceleration, you must calculate this acceleration. You can then use this acceleration to find the angular displacement during this period.

    Phase Two:Constant Angular Velocity

    From t=15 to t=47 you have a constant angular velocity, which you can calculate from the above phase.

    Edit: Radou beat me to it
  5. Oct 30, 2006 #4


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    ... [:cool:]
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