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Homework Help: Calculating moments of a beam

  1. Mar 24, 2012 #1

    1. The problem statement, all variables and given/known data
    Find the Fay this is static equilibrium so ƩF=0 and ƩM=0

    2. Relevant equations

    = 2x5 + (-4x25) + (2Fby)
    Fby= 45 Newtons
    Using ƩFy we get Fay= impossible!!

    Now if take the moment about point B i get
    = (4x5)+(-2x25)+2Fay
    Fay = 15kN
    Using ƩFy we get Fby=15Kn
    Can someone tell me where i went wrong plz?? I just dont get it
  2. jcsd
  3. Mar 24, 2012 #2


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    Science Advisor
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    Gold Member

    not impossible, you get a negative value for Fay; what does that imply about the direction of Fay?
    what is its direction?
    No, watch plus and minus signs and their meaning.
  4. Mar 24, 2012 #3
    Thanks so much I now see my mistake. Got the directions mixed up!!! Damn gotta be more careful
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