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Unit of Torque: Nm vs. Nm/°

  1. Aug 28, 2011 #1
    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 [Broken]

    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: May 5, 2017
  2. jcsd
  3. Aug 28, 2011 #2

    SteamKing

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    No. Degrees are considered to be units. The magnitude of a torque or moment is independent of any angle.
     
  4. Aug 28, 2011 #3

    A.T.

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    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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