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Homework Help: Help finding the magnitude of the net force

  1. Jan 23, 2013 #1
    Three students converge on the last textbook in the store. All three grab it and begin to pull in the directions shown in the above figure. Student A exerts a force of 61.88 N, student B pulls with a force of 31.92 N, and student C pulls with a force of 104.20 N at an angle θ(theta)=80.8 degrees above the -x axis.
    Considering these three forces (ignore the force of gravity on the book), what is the magnitude of the net force on the book?

    Give the angle of the resultant force with respect to the +x-axis. Assume the counter-clockwise direction to be positive and the clockwise direction to be negative.

    I honestly have no idea where to begin. I know how to find the net force with 2 forces being exerted but not three, and definitely not with an angle! I would really appreciate help, even if its just hints point me in the right direction!
    Last edited: Jan 23, 2013
  2. jcsd
  3. Jan 23, 2013 #2


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    Staff: Mentor

    Welcome to the PF.

    Just resolve each force into its x & y components, and add the components to get the resultant x & y components. Then you can convert that back into an overall force magnitude and direction.

    Please show us your work on that (and post the diagram if you can too).
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