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Homework Help: Angular acceleration

  1. Nov 12, 2012 #1
    How may I calculate the angular acceleration of a wheel of radius R given that its vector of total acceleration of a point on its perimeter forms an angle of pi/6 wrt the tangential acceleration at that point at t=1sec after the body has begun its motion?

    My attempt at a solution:

    a_tot = (-r*w^2,r*dw/dt)
    a_tang = (0,r*dw/dt)
    Their dot product/product of lengths should yield cosine 30.
    I got dw/dt = sqrt(3)w^2

    Is that correct? Don't I also know that wt = (pi/2 - pi/6)? Couldn't I have calculated w using that?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Nov 12, 2012 #2


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    hi peripatein! :smile:

    (try using the X2 button just above the Reply box :wink:)
    yes :smile:

    but wouldn't it be easier to say that the ratio of the radial and tagential components must be tan30° ? :wink:
    not following you :confused:
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