Foot-pound (energy)

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The foot-pound force, or simply foot-pound (symbol: ft·lbf or ft·lb) is an English unit of work or energy. It is the amount of energy expended when a force of one pound acts through a distance of 1 foot along the direction of the force.

It is also a unit of torque: 1 foot-pound is the amount of torque created by a force of 1 pound acting at a perpendicular distance of 1 foot from a pivot point. Pound-foot is sometimes used as the name for the unit of torque to distinguish it from the unit of energy. Pound-foot is used by engine manufacturers in specifying the torque output of an engine.

The SI energy unit is the joule (J), which is dimensionally equivalent to the newton-meter (N·m), the SI unit of torque.

Conversions

1 foot-pound is equivalent to:

  • 1.355 817 948 331 400 4 joule (J) (exactly)
  • 1.355 817 948 331 400 4 newton meter (N·m) (exactly)
  • 13 558 179.483 314 004 ergs (erg) (exactly)
  • ~0.001 285 067 British Thermal Unit IT (BtuIT or BTUIT)
  • ~0.323 832 calorie IT (calIT) or ~0.000 323 832 "food calorie" (kcal or Cal)
  • ~32.174 049 foot-poundals (ft pdl)
  • 12 inch-pound force (in·lbf or sometimes informally written: ″#)
  • 192 inch-ounce force (in·ozf)

Conversion of units#Energy, work, or heat

Power

The foot-pound force per minute (ft·lbf/min) and foot-pound force per second (ft·lbf/s) are English units of power derived from the foot-pound force. The English horsepower is defined in terms of it.

  • 1 watt (W) ≈ 44.253 728 96 ft·lbf/min
  • 1 horsepower (hp) (Imperial mechanical) = 33000 ft·lbf/min = 550 ft·lbf/s

See also