The poundal (symbol: pdl) is a unit of force, introduced in 1877, that is part of the Absolute English system of units,[citation needed] which itself is a coherent subsystem of the foot–pound–second system.
The poundal is defined as the force necessary to accelerate 1 pound-mass at 1 foot per second squared.
English units require re-scaling of either force or mass to eliminate a numerical proportionality constant in the equation F = ma.
[citation needed] The poundal represents one choice, which is to rescale units of force.
For example, a force of 1200 poundals is required to accelerate a person of 150 pounds mass at 8 feet per second squared:
Note: Slugs (32.174049 lb) and poundals (1/32.174049 lbF ) are never used in the same system, since they are opposite solutions of the same problem.
Specifically, computing F = ma on the moon or in deep space as poundals, lb⋅ft/s2 or lbf = slug⋅ft/s2, avoids the constant tied to acceleration of gravity on earth.