Foot-pound is a unit of work and energy in the inch-pound system of measurement customarily used in the United States. Physicists define work as the arithmetical product of a force that acts on an object and the distance through which the object moves. In other words, the amount of work done equals the force times the distance. Thus, 1 foot-pound of work is done when a force of 1 pound acts on an object that moves 1 foot. When the force is 2 pounds and the object moves 3 feet, 6 foot-pounds of work are done.
Energy is the ability to do work. One foot-pound is the energy needed to move an object 1 foot against the opposition of 1 pound of force. Thus, it takes 1 foot-pound of energy to raise an object that weighs 1 pound a distance of 1 foot. In this case, the opposing force is the weight of the object. When a 2-pound object is raised 3 feet, 6 foot-pounds of energy are used. These are examples of mechanical energy. The foot-pound can also be used to measure any other form of energy, such as chemical energy.
In the metric system of measurement, work and energy are measured in joules. One foot-pound equals 1.356 joules. Foot-pound is abbreviated as ft.-lb.
See also Energy (Units of work and energy); Joule; Work.
