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Homework Help: Net torque! Need help with angular acceleration.

  1. Dec 8, 2009 #1
    1. The problem statement, all variables and given/known data
    A certain wheel has a rotational inertia of 12 kg m2. As it turns through 5.0 rev its angular velocity increases from 5.0 rad/s to 6.0 rad/s. If the net torque is constant, its value is:

    2. Relevant equations
    Angular acceleration = dW/dT
    Net torque = (angular acceleration)*(rotational inertia)
    Θf = Θi + (Wi)(dT) + [tex]\frac{1}{2}[/tex] [tex]\alpha[/tex][tex]\Delta[/tex]t2

    3. The attempt at a solution
    I have dW = 5-6=-1rad/s
    I am confused on how to find dT. The equations have have both have two unknowns (t & [tex]\alpha[/tex])
    Last edited: Dec 8, 2009
  2. jcsd
  3. Dec 8, 2009 #2
    why dont you try this formula:

    (wf)^2 - (w0)^2 = 2 alpha * omega.
  4. Dec 10, 2009 #3
    Thank you so much! That worked. I'm glad you had that equation. I did not, and it happened to be on the test.
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