1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Direction of moment forces

  1. Nov 26, 2007 #1
    1. The problem statement, all variables and given/known data

    How do u find whether the moment is negative or positive in the three examples shown?? Even if you use the right hand rule, for case 2 i have seen that the moment is negative and not positive. I am taking counter clockwise as positive moments. Please help out. Thanks!

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Nov 26, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    If you take ccw as positive, then the moment vector points out of the page toward you, using the right hand rule, in the positive Z direction. It follows that cw moments are then negative, pointing in the negative Z direction into the page away from you. So the first 2 moments, being cw are negative, and the last, being ccw, is positive, per your chosen convention.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook