Poundals to Pounds-force (pdl to lbf)
1 poundal equals 0.03108095017 pounds-force (rounded).
How to convert poundals to pounds-force
To convert poundals to pounds-force, multiply the number of poundals by 0.03108095017. The factor is rounded to 10 significant digits. To go the other way, multiply pounds-force by 32.17404856 (rounded).
pounds-force = poundals × 0.03108095017
Example: 10 poundals = 0.3108095017 pounds-force.
About these units
Poundal (pdl)
About 0.138255 newtons: the force that accelerates one pound by one foot per second squared. The imperial absolute unit of force.
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.
1 poundal = 0.1382549544 newtons (approximately).
Sources: Wikipedia: Poundal; Wikipedia: Pound (force); NIST SP 811, Appendix B.8
Pound-force (lbf)
Exactly 4.4482216152605 newtons: the weight of a one-pound mass under standard gravity. The US unit of force.
People have used the pound-force since the eighteenth century for low-precision work, long before anyone needed to define it carefully. A pound of material on Earth's surface pulls with about a pound of force, which made it convenient to treat the two as one. The twentieth century demanded a precise definition: one pound-force is the avoirdupois pound, exactly 0.45359237 kg, multiplied by standard gravity of 9.80665 meters per second squared, which comes to about 4.448 newtons.
Because the unit is not simply mass times acceleration in its own system, formulas in English engineering units need a conversion constant of about 32.174 pound-feet per pound-force second squared. A slug, 32.174049 pounds of mass, is what one pound-force accelerates at one foot per second squared. In the US, jet and rocket thrust is often given as pounds of thrust: each Space Shuttle solid rocket booster produced 3,300,000 pounds-force. Earth's gravity varies by up to about half a percent between equator and pole, which low-precision work can ignore.
1 pound-force = 4.448221615 newtons (approximately).
Sources: Wikipedia: Pound (force); NIST Guide to the SI, Appendix B.8: conversion factors
Related conversions
- Pounds-force to poundals (reverse)
- Poundals to newtons
- Poundals to kilonewtons
- Newtons to pounds-force
- Kilonewtons to pounds-force
- Kilograms-force to pounds-force
- Meganewtons to pounds-force
- Millinewtons to pounds-force
- Ounces-force to pounds-force
- Grams-force to pounds-force
- Dynes to pounds-force
- Kips to pounds-force
- Tons-force (short) to pounds-force
- Tons-force (long) to pounds-force
- Tonnes-force to pounds-force
See all force units.