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Statics: Moment about an axis

  1. Sep 7, 2015 #1
    1. The problem statement, all variables and given/known data
    Two 20 lb forces are applied to a ratchet wrench down at A and up at B to loosen bolt β. Find the sum of the moments of the two forces about the axis (x) of the bolt.

    2. Relevant equations
    What are the moments at point A, B, and Q?
    How do I find the moment about the x axis and not at the bolt β?

    3. The attempt at a solution
    Not sure how to set up the problem because of the different pivots Q and B which are angled.


    hw1.png
     
  2. jcsd
  3. Sep 7, 2015 #2
    First step: What torque is transmitted down the 8" wrench extension?
    Have you studied torques as vectors?
     
  4. Sep 7, 2015 #3
    Yes I believe I have, but we call them moments? Could I just find the moment on the 8" wrench extension and project it on the x axis by multiplying it by cos(45) to find the answer?
     
  5. Sep 7, 2015 #4
    Yes, I believe that's right.
     
  6. Sep 7, 2015 #5
    This is my attempt at the problem, I feel like it is wrong because of my Force vector.
     

    Attached Files:

  7. Sep 8, 2015 #6
    Unfortunately, I can open, but can't read your attachment. What is the moment in the wrench extension?
     
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