Why Are Clockwise Moments Negative and Anti-Clockwise Moments Positive?

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SUMMARY

Clockwise moments are conventionally defined as negative, while anti-clockwise moments are defined as positive due to established conventions in physics and engineering. This convention aligns with the right-hand rule, where the thumb points in the positive direction of the axis, and the fingers curl in the direction of positive rotation. However, the discussion highlights that these conventions are arbitrary, and consistency in application is more critical than adherence to a specific rule. Users can adopt alternative conventions as long as they clearly communicate their chosen system.

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  • Familiarity with the right-hand rule and its application in three-dimensional space.
  • Knowledge of coordinate systems and their conventions in physics.
  • Basic grasp of vector mathematics and rotational dynamics.
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  • Research the application of the right-hand rule in vector calculus.
  • Explore the implications of different conventions in physics, such as torque and angular momentum.
  • Study the relationship between rotational dynamics and coordinate systems in engineering.
  • Investigate how conventions affect calculations in 3D modeling and simulations.
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Students of physics, engineers, and anyone involved in mechanics or 3D modeling who seeks to understand the implications of rotational conventions and their applications in various fields.

Fiona Rozario
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Why are clockwise moments taken as negative and anti-clockwise moment as positive? Why not the other way around?
 
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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!
 
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)
 
Do whatever you like as long as you are consistent.
 
sophiecentaur said:
Do whatever you like as long as you are consistent.

... and explain which convention you are using!
 

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