A pound-foot (lbf⋅ft) is a unit of torque (a pseudovector). One pound-foot is the torque created by one pound of force acting at a perpendicular distance of one foot from a pivot point. Conversely one pound-foot is the moment about an axis that applies one pound-force at a radius of one foot.
|Unit system||British Gravitational System, English Engineering Units|
|1 lbf∙ft in ...||... is equal to ...|
|SI units||≈ 1.355818 N⋅m|
|Gravitational metric system||≈ 0.1382550 kgf⋅m|
The value in SI units is given by multiplying the following approximate factors:
- One pound (force) = 4.448 222 newtons
- One foot = 0.3048 m
This gives the conversion factor:
- One pound-foot = 1.35582 newton metres.
The name "pound-foot", intended to minimize confusion with the foot-pound as a unit of work, was apparently first proposed by British physicist Arthur Mason Worthington. However, the torque unit is often still referred to as the foot-pound (ft⋅lbf).
Similarly, an inch-pound (more correctly written as pound-inch) is the torque of one pound of force applied to one inch of distance from the pivot, and is equal to 1/ of a pound-foot. It is commonly used on torque wrenches and torque screwdrivers for setting specific fastener tension.
- "Appendix B.9: Factors for units listed by kind of quantity or field of science". NIST Guide to the SI. National Institute of Standards and Technology. September 7, 2016. Retrieved 2018-07-09.
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