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Static equilibrium/torque

  1. Apr 25, 2015 #1
    I understand that for a system to be in static equilibrium the sum of the forces and torques must equal zero. I understand why the torques must net out to zero but not the forces. For example, if you picture a wooden plank pivoted at the center with a small mass on the far left end and a very large mass near the pivot such that the torques net out to zero, the system is not moving yet the forces do not net out to zero. if somebody can please explain, I would be very appreciative.
  2. jcsd
  3. Apr 25, 2015 #2

    Doc Al

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    Staff: Mentor

    Don't forget that the pivot itself exerts an upward force to support the plank and the two masses.
  4. Apr 25, 2015 #3
    oh my gosh! How could I forget that! Thank you very much.. its been bugging me for three days now.
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