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Homework Help: Rotational Dynamics and torque

  1. Oct 28, 2007 #1
    What minimum force F applied horizontally at the axle of the wheel is necessary to raise the wheel over an obstacle of height h? Take r as the radius of the wheel and W as its weight.

    We know torque is equal to the radius x perpendicular force
    T = rFnet

    I think I have to find angular acceleration, α.

    T = rma
    T = rmα
    T = rm(αr)
    T = α(mr^2)
    ΣT = αΣ(mr^2)

    am I on the right track so far?
    How do I incorporate height into this, do I want to find angular acceleration in the y direction?
  2. jcsd
  3. Oct 28, 2007 #2


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    Homework Helper

    Do they give a picture? If not draw a picture... Draw a wheel standing against a block of height h.

    the point where the block and the wheel touch... you want the torque about the point to be zero...

    you have two forces involved for this torque... the weight and the horizontal applied force.
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