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Torque and segmented lever arms

  1. Aug 6, 2010 #1
    My question is: How do you calculate torque when the lever arm is segmented? I have drawn a simple diagram to try to explain what I mean. Does the fact that the weight is now closer to the axis shorten my lever arm, or is the lever arm = D due to the fact that 10lbs is still being applied to the end of the first segment. Thanks.
     

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  2. jcsd
  3. Aug 7, 2010 #2
    Assuming your segmented arms are rigidly attached - they don't rotate at the corner to the right - what you have is a new, shorter "virtual" lever arm, extending from the axis to the point where the weight is hung. You'd need to do the geometry to figure out its actual length, and what the vertical and horizontal components are. In this case, if the weight is hanging so it freely swings at the top, the resulting torque is the weight (force) times the horizontal distance from the axis to the point directly under the weight.

    Scaling the drawing, I make it about 9.5 lb-ft.

    Dave
     

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