Newton-metre

The newton-metre (also newton metre or newton meter; symbol N⋅m
/ref> or N m) is the unit of torque (also called ) in the International System of Units (SI). One newton-metre is equal to the torque resulting from a force of one newton applied perpendicularly to the end of a moment arm that is one metre long. The nonstandard notation ''Nm'' occurs in some fields.

The unit is also used less commonly as a unit of work, or energy, in which case it is equivalent to the more common and standard SI unit of energy, the joule.For example: Eshbach's handbook of engineering fundamentals - 10.4 Engineering Thermodynamics and Heat Transfer "In SI units the basic unit of energy is newton-metre". In this usage the metre term represents the distance travelled or displacement in the direction of the force, and not the perpendicular distance from a fulcrum as it does when used to express torque. This usage is generally discouraged, since it can lead to confusion as to whether a given quantity expressed in newton-metres is a torque or a quantity of energy. However, since torque represents energy transferred or expended per angle of revolution, one newton-metre of torque is equivalent to one joule per radian.BIPM - special names
/ref>

Newton-metres and joules are dimensionally equivalent in the sense that they have the same expression in SI base units,

::$1 \, \text \mathrm = 1 \, \frac \quad , \quad 1 \, \mathrm = 1 \, \frac$

but are distinguished to avoid misunderstandings when a torque is mistaken for an energy or vice versa. Similar examples of dimensionally equivalent units include Pa versus J/m³, Bq versus Hz, and ohm versus ohm per square.

Conversion factors

*1 kilogram-force metre = 9.80665 N⋅m''Concise encyclopedia of plastics'', by Donald V. Rosato, Marlene G. Rosato, Dominick V. Rosato, p621
/ref>

*1 newton-metre ≈ 0.73756215 pound-force-feet
*1 pound-foot ≡ 1 pound-force-foot ≈ 1.35581795 N⋅m
*1 ounce-inch ≡ 1 ounce-force-inch ≈ 7.06155181 mN⋅m (millinewton-metres)
*1 dyne-centimetre = 10⁻⁷ N⋅m

See also

*Bending moment
* Spring scale
*Torque tester
*Newton-second, the derived SI unit of impulse

References

{{SI units

Units of torque
SI derived units