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Homework Help: Uniform angular acceleration

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

    A wheel is subjected to uniform angular acceleration. Initially its angular velocity is zero. During the first 1-s time interval, it rotates through an angle of 90.6degrees.

    (a) Through what angle does it rotate during the next 1-s time interval?(in degrees)

    (b) Through what angle during the third 1-s time interval?(in degrees)

    2. Relevant equations


    3. The attempt at a solution

    I just tried multiplying the 90.6 by 2, and putting in 90.6 itself, because I thought that might be the answer, but I forgot that it was the acceleration, and that the next values would increase in smaller increments, because it is speeding up.
  2. jcsd
  3. Feb 21, 2008 #2
    You can use all your equations you've been using for constant acceleration, like d=1/2at^2+Vi*t, but now you use the rotational "versions"

    so instead of distance in meters, you have the angle traveled in radians, instead of velocity in meters/second, angular velocity in radians/second, and acceleration is radians/s^2

    So in one second it goes from 0 degrees to 90.6 starting from rest(you'll need radians!)this is like knowing distance, time, and initial velocity
  4. Feb 21, 2008 #3
    Okay, so since I have 5400 rev/min, I divide it by 60 to get 90 rev/sec. Then I multiply it by 2*Pi for the angular velocity in radians, right? Or am I doing something wrong?
  5. Feb 21, 2008 #4
    That part's right

    except the unit is radians/second
    Last edited: Feb 21, 2008
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