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Problem 13.8: Apply equilibrium conditions to a see-saw

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A seesaw, usually in equilibrium, is shown in the animation. A little girl named Melody sits on the seesaw and thereby applies a force of 200 N to the seesaw as indicated by the red vector labeled FM. The seesaw weighs 500 N (position is given in meters). Restart.

  1. Where should her dad sit on the seesaw in order to keep the system in equilibrium if he applies a bulky 900 N to the seesaw when sitting on it?
  2. What is the force of the axle on the seesaw, assuming that the only other force applied to the seesaw besides Melody and her dad is the force of the axle?
  3. When Melody's dad wants to practice a circus act by applying a 900 N force to the far right edge of the seesaw, Melody's mom immediately rushes to her aid by applying a downward force on the seesaw to keep the system in equilibrium. If the force of Mom on the seesaw has a magnitude of 750 N, at what location on the seesaw is it applied?

Problem authored by Aaron Titus.

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