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!

Sign for a clockwise moment

  1. Jun 25, 2014 #1
    Why are clockwise moments taken as negative and anti-clockwise moment as positive? Why not the other way around?
     
  2. jcsd
  3. Jun 25, 2014 #2

    UltrafastPED

    User Avatar
    Science Advisor
    Gold Member

    An arbitrary convention. But if you like the right-hand rule, you will find that your right thumb points up if your fingers are curled in the counter-clockwise direction.

    Perhaps the clock makers are the ones with the wrong convention!
     
  4. Jun 25, 2014 #3

    Nathanael

    User Avatar
    Homework Helper

    If you do it the other way around, you'll get the same answers (as long as you are consistent).

    I actually sometimes do it the other way around (because when I visualize 3D coords, the Z axis goes out forward in front of me, so pointing my thumb in the positive direction makes my fingers curl clockwise)

    So for my X and Y axes it's "the right hand rule" but for my Z axis, (in order to be consistent,) it's "the left hand rule"

    (I could just flip my Z axis, but that's very unnatural to me, especially when the Z axis represents time)


    Like Ultrafast said, it's just a convention.


    I just wanted to point out that "the right hand rule" only works if you follow another arbitrary convention (the conventional positive/negative directions of each axis)
     
  5. Jun 25, 2014 #4

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    Do whatever you like as long as you are consistent.
     
  6. Jun 25, 2014 #5

    UltrafastPED

    User Avatar
    Science Advisor
    Gold Member

    ... and explain which convention you are using!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook