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Homework Help: For this instant calculate the magnitudes of the force F and torque M

  1. Apr 21, 2013 #1
    1. The problem statement, all variables and given/known data
    The parallelogram linkage shown moves in the vertical plane with the uniform 6.8-kg bar EF attached to the plate at E by a pin which is welded both to the plate and to the bar. A torque (not shown) is applied to link AB through its lower pin to drive the links in a clockwise direction. When θ reaches 58°, the links have an angular acceleration and an angular velocity of 6.6 rad/s2 and 2.0 rad/s, respectively. For this instant calculate the magnitudes of the force F and torque M supported by the pin at E.

    I have attached an image of the question

    2. Relevant equations

    3. The attempt at a solution

    On the attached image I've added in red what I believe that forces acting on the system are. But aside from this I'm unsure how else to begin on this problem. I suspect that a normal and tangent coordinate system may be beneficial here but I'm not sure where best to place the origin of the system.

    Any advice would be appreciated.

    Attached Files:

  2. jcsd
  3. Apr 22, 2013 #2


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    Staff Emeritus
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    Except for mg, the forces you have labeled are irrelevant for solving this problem.

    First: Find the motion (velocity and acceleration) of point A at the instant indicated.

    How does that compare to the velocity and acceleration of point E ?
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