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Homework Help: Statics Question: Finding resultant force and orientation

  1. Feb 7, 2013 #1

    Determine the magnitude of the resultant force FR. Assume that F1 = 230 and F2 = 395
    Express your answer to three significant figures and include the appropriate units.

    Determine the direction of the resultant force FR , measured counterclockwise from the positive x axis.

    I got the magnitude as 402lb which is correct, but I am having trouble finding the direction of the force.

    I have the following work below

    http://img5.imageshack.us/img5/1954/resultantforce.png [Broken]

    So I get [itex]\phi[/itex]=71.6 degrees

    Now the first quadrant has an angle from F1 to the x axis that measures at 60 degrees. What I did was 71.6-60 degrees = 11.6 degrees and said that was the angle of the resultant force, but this answer is wrong.

    Can anyone explain how to find the angle? Should I be subtracting 360 from 11.6 degrees instead since it wants the position counterclockwise?
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 8, 2013 #2


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    Staff Emeritus
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    Homework Helper

    Why don't you find the components of F1 and F2 and add them to determine the resultant?
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