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    There is a pole of mass M and length L attached to a vertical wall on a hinge at a point X. The weight of it is supported by a wire attached to the other end of the pole which goes over a pulley.
    Model the wire as a model string and the pulley as a model pulley. There are three forces acting on the pole. The weight w, the tension t due to the wire and a force due to the hinge. Choose horizontal and vertical unit vectors and an origin at X.
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    (Original post by creagle92)
    There is a pole of mass M and length L attached to a vertical wall on a hinge at a point X. The weight of it is supported by a wire attached to the other end of the pole which goes over a pulley and is fixed to a particle of mass m. The wire from the pole makes an angle theta with the horizontal direction.
    Model the wire as a model string and the pulley as a model pulley. There are three forces acting on the pole. The weight w, the tension t due to the wire and a force p due to the hinge. Choose horizontal and vertical unit vectors and an origin at X.
    Assuming the pole is in equilibrium, and by taking torques about X, find the angle theta in terms of the above parameters.

    I have found the cross product to get the torques and have
    L*t*sin(theta)-(1/2)*L*M*g=0

    I think that is right so far but I really don't know what to do next.
    Thanks in advance!
    no need for cross products as the whole system is in one plane
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    Not sure what to do then
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    (Original post by creagle92)
    Not sure what to do then
    draw a picture mark all the forces
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    (Original post by creagle92)
    i have position vectors of points of application are:
    p=0
    t=Li
    w=1/2 Li

    and find the torques by taking cross product of these with their component forms so
    torque p = 0
    torque t = Li x T = L*Tsin(theta) k
    torque w = 1/2 Li x W = -1/2 L*M*g k
    please post a photo of the question.
    (is the pole horizontal?)
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    one minute I was looking at a photo the next minute it was gone ...
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    (Original post by TeeEm)
    one minute I was looking at a photo the next minute it was gone ...
    Such is life!
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    (Original post by ghostwalker)
    Such is life!
    for some reason the OP deleted his post and picture and disappeared.

    I did glance at the picture for a few seconds and it is elementary mechanics as the pole is horizontal. I think this question came from some engineering course.
 
 
 
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Updated: October 30, 2015

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