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Homework Help: Equilibrium - Ladder against wall

  1. Aug 14, 2012 #1
    1. The problem statement, all variables and given/known data
    A 7.0kg ladder is placed against a smooth wall so that it makes an angel of 72deg to the horizontal. A 56kg person stands 4.0m from the bottom of the ladder.

    What force does the wall exert on the ladder?
    What is the coefficient of friction between the ladder and the ground?

    2. Relevant equations

    EFy=0 : Fy=69+540
    EFx=0: Fx=Fwall
    ET=0: (5.71Fwall)= (69*0.93)+(540 * 1.23)

    Ffriction = uFnormal

    3. The attempt at a solution

    Force exerted by wall is 129.5N. Friction force is therefore 129.5N

    Stuck as to what force is the normal force used to calculate coefficient of friction.
  2. jcsd
  3. Aug 14, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    What about the force from the floor? (That's the missing normal force.)
  4. Aug 14, 2012 #3
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