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| Foot-pound | |
|---|---|
| Unit system | English engineering units andBritish gravitational system |
| Unit of | Energy |
| Symbol | ft⋅lbf, ft⋅lb |
| Conversions | |
| 1 ft⋅lbfin ... | ... is equal to ... |
| SI units | 1.355818 J |
| CGS units | 13,558,180 erg |
Thefoot-pound force (symbol:ft⋅lbf,[1]ft⋅lbf,[2] orft⋅lb[3]) is a unit ofwork orenergy in theengineering andgravitational systems inUnited States customary andimperial units of measure. It is the energy transferred upon applying aforce of onepound-force (lbf) through a lineardisplacement of onefoot. The correspondingSI unit is thejoule, though in terms of energy, one joule is not equal to one foot-pound.
The termfoot-pound is also used as a unit oftorque (seepound-foot (torque)). In the United States this is often used to specify, for example, the tightness of afastener (such asscrews andnuts) or the output of anengine. Although they aredimensionally equivalent, energy (ascalar) and torque (aEuclidean vector) are distinct physical quantities. Both energy and torque can be expressed as a product of a force vector with a displacement vector (hence pounds and feet); energy is thescalar product of the two, and torque is thevector product.
Although calling the torque unit "pound-foot" has been academically suggested, both are still commonly called "foot-pound" in colloquial usage. To avoid confusion, it is not uncommon for people to specify each as "foot-pound of energy" or "foot-pound of torque" respectively.
Insmall armsballistics and particularly in theUnited States, the foot-pound is often used to specify themuzzle energy of abullet.
1 foot pound-force is equivalent to:
1 foot pound-force per second is equivalent to:
Related conversions: