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Homework Help: Knocking over a Post

  1. Nov 29, 2005 #1
    I can't seem to figure out this question:

    One end of a post weighing 400 N and with height h rests on a rough rope fastened to the surface and making an angle of 36.9 degrees with the post. A horizontal force is excerted on the post. If the force (F) is applied at the midpoint of the post, what is the largest value it can have without causing the post to slip.

    I started working out the horizontal and vertical forces, but i can't seem to work out the tension in the rope, that can help me figure out F, any suggestions?
  2. jcsd
  3. Nov 29, 2005 #2
    Ok, i figured it out i think, please check me:
    The sum of the torques taken at the pivot point is equal to n(h)-Tcos(36.9)=0, which gave me a tension of 500 N. I then used this to find that the force is equal to 420 N.

    But what if the force is applied 6/10 of the way from the ground to the top of the post?
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