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The foot pound-force (symbol: ft⋅lbf or ft⋅lb)[1] 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.

Foot-pound
Unit systemEnglish Engineering units and British Gravitational System
Unit ofEnergy
Symbolft⋅lbf 
Conversions
1 ft⋅lbf in ...... is equal to ...
   SI units   1.355818 J
   CGS units   13,558,180 erg

UsageEdit

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 used to specify, for example, the tightness of a bolt or the output of an engine. Although they are dimensionally equivalent, energy (a scalar) and torque (a Euclidean 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 the scalar product of the two, and torque is the vector product.

Conversion factorsEdit

EnergyEdit

1 foot pound-force is equivalent to:

PowerEdit

1 foot pound-force per second is equivalent to:

Related conversions:

  • 1 watt44.25372896 ft⋅lbf/min = 0.737562149333 ft⋅lbf/s
  • 1 horsepower (mechanical) = 33,000 ft⋅lbf/min = 550 ft⋅lbf/s

See alsoEdit

ReferencesEdit

  1. ^ Budynas, Richard G.; Nisbett, J. Keith (2014-01-27). Mechanical Engineering Design. McGraw Hill Education. ISBN 978-0073529288.