Foot-pound (energy) Foot-pound (energy) The foot pound-force (symbol: ft⋅lbf or ft⋅lb) is a unit of work or energy in the Engineering and Gravitational Systems in United States customary and imperial units of measure. It is the energy transferred upon applying a force of one pound-force (lbf) through a linear displacement of one foot. The corresponding SI unit is the joule. The foot-pound is often used to specify the muzzle energy of a bullet in small arms ballistics, particularly in the United States. "Foot-pound" is also used as a unit of torque (see "pound-foot (torque)"). In the United States this unit is often
Work (physics) work, but this can be confused with the unit newton-metre, which is the measurement unit of torque. Usage of N⋅m is discouraged by the SI authority, since it can lead to confusion as to whether the quantity expressed in newton metres is a torque measurement, or a measurement of work. Non-SI units of work include the newton-metre, erg, the foot-pound, the foot-poundal, the kilowatt hour, the litre-atmosphere, and the horsepower-hour. Due to work having the same physical dimension as heat, occasionally measurement units typically reserved for heat or energy content, such as therm, BTU and Calorie, are utilized as a