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Homework Help: Force/vectors problem

  1. Feb 4, 2009 #1
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    http://g.imageshack.us/img10/scan0001px3.jpg/1/" [Broken]

    http://g.imageshack.us/img27/scan0001xe4.jpg/1/" [Broken]

    Well I just set the sum of x and y components equal to 0 and got: force 3 = -65N in x and 43.3N in y which gave me a magnitude of 78.1 N and 146.3 degrees counterclockwise from x-axis. Right? Wrong? Thanks for your help.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Feb 4, 2009 #2


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    Doesn't look right. I checked the vertical part - F1 has 25 N down. F3 should have 25 N up but, according to your answer, has 78.1*cos(146.3-90) = 43N up.
  4. Feb 4, 2009 #3
    No, I don't think it's entierly correct.. I got my doubts first when it came to your angle - if you mean from the x-axis to the right (if you understand what I mean, I don't know the terminology at the moment), F3 is in the second quadrant, and if it's from the other x-axis, so to speak, it's in the fourth and neither make much sense.

    I've been thinking for a while and it's your x-component that's wrong.. It's not supposed to be -65. It's supposed to be F2 - F1X, right? Redo this step.

    Edit: Nah, the vertical's correct. The vertical is = F3 * sinθ, not cosθ. (In reply to what Delphi51 said (; )
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