Han wrote in USMA 16946: >British Gravitational has this unit of force (comparable with the kgf): > >pound force (lbf or lb) > >a traditional unit of force. Traditional measuring systems did not >distinguish between force and mass units. A force of one pound is simply the >gravitational force experienced at the Earth's surface by a mass of one >pound. To compute this force, we multiply the mass by the acceleration of >gravity, following Newton's law F = ma. Since one pound of mass is 0.453 592 >kilograms and the acceleration of gravity averages 9.806 65 meters per >second per second at the surface of the Earth, one pound force equals the >product of these two numbers, 4.448 221 615 newtons. The symbol lbf should >be used for the pound force to distinguish it from the pound of mass > >British Absolute. It has a pure unit of force, just as SI has the newton. It >is used far less than the lbf. > >poundal (pdl or pl)
The poundal was the British physicists unit. British engineers regard the pound-force as their base unit. The Royal Aircraft Establishment in 1940 used the "slug" as their unit of mass. It was equal to 32.2 pounds-mass. In that way F = m.a, where F is in poouns-force, m is in slugs, and a is in feet per second squared. Joseph B.Reid 17 Glebe Road West Toronto M5P 1C8 TEL. 416-486-6071
