The **poundal** is a non-SI unit of force. It is a part of the absolute foot-pound-second system of units, a coherent subsystem of English units introduced in 1879, and one of several specialized subsystems of mechanical units used as aids in calculations. It is defined as 1 lb·ft·s^{-2}, or in words, as the force necessary to accelerate a pound of mass at 1 foot per second, per second. Cover of brochure The International System of Units. ...
The word unit means any of several things: Unit of measurement, a fundamental quantity of measurement Units (computer program), a popular program that does unit conversion Units of energy, the units for energy measurements Units conversion by the Factor-label method Functional unit, a component of a computer system such...
In physics, a force is anything that causes a free body with mass to accelerate. ...
The Imperial units or the Imperial system is a collection of English units, first defined in the Weights and Measures Act of 1824, later refined (until 1959) and reduced. ...
1879 (MDCCCLXXIX) was a common year starting on Wednesday (see link for calendar). ...
English units require either re-scaling of either force or mass to eliminate a numerical proportionality constant in the equation *F* = *m**a*. The poundal represents one choice, which is to rescale units of force. Since a pound of force accelerates a pound of *mass* at about 32 ft/s² (the acceleration of gravity = g), the smaller unit of force represented by the *poundal* is chosen as that force which accelerates a 1-pound mass at 1 foot per second^2. The poundal is only about 1/32 of a pound of force. The poundal-force, pound-mass system is contrasted with an alternate system in which pounds are used as *force*, and instead, the *mass* unit is rescaled by a factor of 32. If *force* is given in *pounds* rather than poundals, then an acceleration of one foot per second^2 is induced in a *mass* of about 32 pounds mass, for each applied pound of *force*. The mass unit of about 32 mass-pounds (32.2 to three digits) in this alternate system, is called a slug. The slug is an English unit of mass. ...
Note that slugs and poundals are never used in the same system, since each exists to solve the same problem, so that both should not be used together. 1 pdl = 0.138 254 954 376 newton (N) exactly The newton (symbol: N) is the SI unit of force. ...
**Units of force** | Newton (SI unit) | Dyne | Kilogram-force (Kilopond) | Pound-force | **Poundal** | 1 N | = 1 kg·m/s² | = 10^{5} dyn | ≈ 0.10197 kp | ≈ 0.22481 lb_{f} | ≈ 7.2330 pdl | 1 dyn | = 10^{−5} N | = 1 g·cm/s² | ≈ 1.0197×10^{−6} kp | ≈ 2.2481×10^{−6} lb_{f} | ≈ 7.2330×10^{−5} pdl | 1 kp | = 9.80665 N | = 980665 dyn | = *g*_{n}·(1 kg) | ≈ 2.2046 lb_{f} | ≈ 70.932 pdl | 1 lb_{f} | ≈ 4.448222 N | ≈ 444822 dyn | ≈ 0.45359 kp | = *g*_{n}·(1 lb) | ≈ 32.174 pdl | 1 pdl | ≈ 0.138255 N | ≈ 13825 dyn | ≈ 0.014098 kp | ≈ 0.031081 lb_{f} | = 1 lb·ft/s² | The value of *g*_{n} as used in the official definition of the kilogram-force is used here for all gravitational units. | |