Is the unit of torque Nm or Nm/°?

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SUMMARY

The unit of torque is definitively Newton metre (Nm), and while it can be expressed in terms of energy per angle, such as joules per radian, it is incorrect to represent torque as (Nm)/°. Torque is fundamentally a measure of rotational force and is independent of the angle unit used. The discussion clarifies that angles, whether in radians or degrees, do not have physical units, reinforcing that torque should be expressed solely in Nm.

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lmelbye
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Hello everybody

Normally you say that the unit of torque is Nm but could also be (Nm)/°.?

I'm claiming this because of the fact that you normally do not give radians any unit, and that is why you just write Nm and not (Nm)/rad.

SI claims that: "torque may be thought of as the cross product of force and distance, suggesting the unit Newton metre, or it may be thought of as energy per angle, suggesting the unit joule per radian"
http://www.bipm.org/en/si/si_brochure/chapter2/2-2/2-2-2.html

We have:

Force*distance=energy =>
[Nm] = [J] which leads to:
[J/rad] = [Nm]/[rad]

So, am I right when I say that unit of torque could be Nm as well as (Nm)/°?
 
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No. Degrees are considered to be units. The magnitude of a torque or moment is independent of any angle.
 
lmelbye said:
So, am I right when I say that unit of torque could be Nm as well as (Nm)/°?
Angles don't have physical units. Radians is just a ratio of two lengths. Degrees is that ratio multiplied by some constant factor.
 

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