Poundal (pdl)

Imperial (British)Historical unit (no longer in standard use)

About 0.138255 newtons: the force that accelerates one pound by one foot per second squared. The imperial absolute unit of force.

1 poundal = 0.1382549544 newtons (approximately).

1 poundal = 0.1382549544 newtons

About the poundal

Introduced in 1877, the poundal was built to solve a bookkeeping annoyance in the foot-pound-second system. It is the force that gives a one-pound mass an acceleration of one foot per second squared, so Newton's second law F = ma works with no extra constant. Wikipedia does not name who proposed it. The value is exactly 0.138254954376 N, derived from the international foot and pound.

Compared with the pound-force, the poundal is small, about 0.03108 of it, or roughly one thirty-second, because gravity at the surface gives 32.174 ft/s2. Its appeal is that it does not depend on gravity, so it works equally on the Moon or in deep space. A 150 lb mass accelerated at 8 ft/s2 needs 1,200 poundals, for example. The alternative cure for the same problem is the slug, a mass unit of about 32 lb used with pound-force. Both approaches saw little industrial use, and today the poundal mostly survives in textbooks and conversion tables.

Sources: Wikipedia: Poundal; Wikipedia: Pound (force); NIST SP 811, Appendix B.8

Poundal conversion chart

1 poundal expressed in every other force unit:

Unit1 poundal
Newtons0.1382549544
Kilonewtons0.0001382549544
Pounds-force0.03108095017
Kilograms-force0.01409808185
Meganewtons1.382549544×10⁻⁷
Millinewtons138.2549544
Ounces-force0.4972952027
Grams-force14.09808185
Dynes13,825.49544
Kips0.00003108095017
Tons-force (short)0.00001554047509
Tons-force (long)0.00001387542418
Tonnes-force0.00001409808185
Sthènes0.0001382549544

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