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Homework Help: Rectangular sheets, angular velocity time?

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

    Two thin rectangular sheets (0.26 m 0.35 m) are identical. In the first sheet the axis of rotation lies along the 0.26 m side, and in the second it lies along the 0.35 m side. The same torque is applied to each sheet. The first sheet, starting from rest, reaches its final angular velocity in 7.3 s. How long does it take for the second sheet, starting from rest, to reach the same angular velocity?
    in seconds

    2. Relevant equations

    3. The attempt at a solution

    how can this be figured out?

    what is the theta?

    i would use this equation theta = 1/2(w0 + wf)*t

    and solve for wf.

    not sure what theta is in the equation though.
  2. jcsd
  3. Dec 1, 2007 #2
    Use the equation

    [tex]\tau\ = I\alpha}[/tex]

    From this you will get the moment of inertia. But beware this the moment of inertia about the 0.26m side. ..you will have to find it with respect to the o.35 side.Once done that again apply the above equation.

    Then apply the kinematic equation and you will get the answer.
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