Is the unit of torque Nm or Nm/°?

  • Thread starter Thread starter lmelbye
  • Start date Start date
  • Tags Tags
    Torque Unit
AI Thread Summary
The unit of torque is primarily expressed as Newton meters (Nm), and while it can be conceptually related to energy per angle, it is not typically represented as Nm/°. Angles, whether in radians or degrees, do not have physical units; radians are a dimensionless ratio, and degrees are a scaled version of that ratio. Torque is fundamentally defined as the cross product of force and distance, making its unit independent of any angular measurement. Thus, torque should be referred to solely as Nm, not as Nm/°.
lmelbye
Messages
1
Reaction score
0
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)/°?
 
Last edited by a moderator:
Physics news on Phys.org
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.
 
I have recently been really interested in the derivation of Hamiltons Principle. On my research I found that with the term ##m \cdot \frac{d}{dt} (\frac{dr}{dt} \cdot \delta r) = 0## (1) one may derivate ##\delta \int (T - V) dt = 0## (2). The derivation itself I understood quiet good, but what I don't understand is where the equation (1) came from, because in my research it was just given and not derived from anywhere. Does anybody know where (1) comes from or why from it the...
Back
Top