Editing Pound (force) (section)

== Foot–pound–second (FPS) systems of units ==
{{main|Foot–pound–second system}}
In some contexts, the term "pound" is used almost exclusively to refer to the unit of force and not the unit of mass. In those applications, the preferred unit of mass is the slug, i.e. lbf⋅s<sup>2</sup>/ft. In other contexts, the unit "pound" refers to a [[Pound (mass)|unit of mass]].  The international standard symbol for the pound as a unit of mass is lb.<ref>IEEE Std 260.1™-2004, IEEE Standard Letter Symbols for Units of Measurement (SI Units, Customary Inch-Pound Units, and Certain Other Units) </ref> 

{{GravEngAbs}}
In the "engineering" systems (middle column), the [[weight]] of the mass unit (pound-mass) on Earth's surface is approximately equal to the force unit (pound-force). This is convenient because one pound mass exerts one pound force due to gravity. Note, however, unlike the other systems the force unit is not equal to the mass unit multiplied by the acceleration unit<ref>The acceleration unit is the distance unit divided by the time unit squared.</ref>—the use of [[Newton's laws of motion|Newton's second law]], {{nowrap|1=''F'' = ''m'' ⋅ ''a''}}, requires another factor, [[gc (engineering)|''g<sub>c</sub>'']], usually taken to be 32.174049&nbsp;(lb⋅ft)/(lbf⋅s<sup>2</sup>).
"Absolute" systems are ''coherent'' systems of units: by using the slug as the unit of mass, the "gravitational" FPS system (left column) avoids the need for such a constant. The [[SI]] is an "absolute" metric system with kilogram and meter as base units.