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: Engineering Mechanics: Notation question

  1. Oct 1, 2014 #1
    In a problem involving moments where we have a 2 point is space: m and n.
    We want the moment about M due to a force applied at N.
    We know the equation is Moment = r (m/n) * F

    So, does r (m/n) represent the (x,y,z) coordinates from the point N to M or M to N?
  2. jcsd
  3. Oct 1, 2014 #2
    The direction has to be perpendicular to the applied force. So, if the force is applied along the y axis, the direction should be in x axis. Hope that helps.
  4. Oct 2, 2014 #3


    User Avatar
    Gold Member

    The calculation of a moment is usually done in vector (cross product) form,
    M = required moment (a vector)
    = rn/m x F

    Note that, in the subscript on r, the first item is the point where F is applied while the second is the reference point for the moment.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted