1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Statics- Resultant couple moment

  1. Jun 8, 2013 #1
    1. The problem statement, all variables and given/known data
    If F_1 = 100N , F_2 = 120N and F_3 = 80N , determine the magnitude and coordinate direction angles of the resultant couple moment.

    2. Relevant equations
    M=Fd
    M=r x F
    MR=Ʃ(r x F)


    3. The attempt at a solution
    I found the couple moment for each force:
    M1=F1d=100(0.2) or (-20j using right hand rule)
    M2=F2d=120(0.2) or +24i
    M3=F3d=80(0.2) or -16k
    M4=this is what im having problems with...not sure how to get the moment for F4... if do 150(.3)(cos30)=38.97 i get the wrong resultant.

    The correct answer should be (MC)R=71.9 Nm...
    Any help would be greatly appreciated.
     

    Attached Files:

  2. jcsd
  3. Jun 8, 2013 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    hi rico22! :smile:
    i don't get 71.9 unless i use .33 instead of .3 :redface:
     
  4. Jun 8, 2013 #3

    TSny

    User Avatar
    Homework Helper
    Gold Member

    Note that the F4 couple is not in the x-direction. It is parallel to the xy plane but it has both x and y components which you will need to work out.
     
  5. Jun 9, 2013 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    ooh, i didn't notice that! :redface:

    i read the axis of that pipe, and the short line above the positive x-axis, as one continuous straight line! :rolleyes:

    yes, now i get 71.9 … thanks, Tsny :smile:
     
  6. Jun 11, 2013 #5
    thanks for the replies guys...
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Statics- Resultant couple moment
Loading...