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Homework Help: Translational and Rotational speeds

  1. Jan 13, 2008 #1
    1. The problem statement, all variables and given/known data
    If a cylinder rolls down a 3.04 meter ramp with a 30 degree incline without slipping, how fast will the rotational and translational speeds be when the cylinder reaches the bottom of the ramp?

    2. Relevant equations
    mgh = K_rotational + K_translational
    K_rotational = 1/2*I*omega^2
    I_cylinder = 1/2*m*r^2
    K_translational = 1/2*m*v^2
    v= r*omega

    3. The attempt at a solution
    I can find out the translational speed by using the equation [tex] mgh = \frac{1}{2} * (\frac{1}{2} m r^2) \omega^2 + \frac{1}{2} m v^2 [/tex]
    Which you can reduce down to [tex] mgh = 1.5 v^2 [/tex] Since we know m,g and h we can solve for v.
    But I can't seem to find a way to solve for omega without knowing the radius, when i reduce that equation down to solve for omega I always left with the radius somewhere. It may just be that you cannot solve for omega, but if you can find a way teh help will be really appreciated.
  2. jcsd
  3. Jan 14, 2008 #2

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    What if you put w=v/r?
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