Newton-metre | |
---|---|

One newton-metre is the torque resulting from a force of one newton applied perpendicularly to the end of a moment arm that is one metre long. | |

General information | |

Unit system | SI derived unit |

Unit of | torque |

Symbol | N⋅m or N m |

Conversions | |

1 N⋅m in ... | ... is equal to ... |

FPS system | 0.73756215 lbf ft |

inch⋅pound-force | 8.8507 in lbf |

inch⋅ounce-force | 141.6 in oz |

The **newton-metre** (also **newton metre**; symbol **N⋅m**^{[1]} or **N m**^{[1]}) is a unit of torque (also called *moment*) in the SI system. 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.^{[2]} 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,^{[3]} since it can lead to confusion as to whether a given quantity expressed in newton-metres is a torque or a quantity of energy.^{[4]} However, since torque represents energy transferred or expended per angle of revolution, one newton-metre of torque is equivalent to one joule per radian.^{[4]}

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

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/m^{3}, Bq versus Hz, and ohm versus ohm per square.

## Conversion factors

- 1 kilogram-force metre = 9.80665 N⋅m
^{[5]}^{[6]} - 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

- ^
^{a}^{b}BIPM – unit symbols **^**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".**^**Fundamentals of Physics, 9th edition by Halliday Resnick Ralker, p. 309. "The SI unit of torque is the newton-meter. In our discussion of energy we called this combination the joule. But torque is*not*work and torque should be expressed in newton-meters,*not*joules. google books link- ^
^{a}^{b}BIPM - special names **^***Mechanical Engineering Formulas Pocket Guide*, p6**^***Concise encyclopedia of plastics*, by Donald V. Rosato, Marlene G. Rosato, Dominick V. Rosato, p621