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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

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    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

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    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

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

    UltrafastPED

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    ... and explain which convention you are using!
     
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