Some fields of
engineering
Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad rang ...
in the United States use a system of measurement of physical quantities known as the English Engineering Units. Despite its name, the system is based on
United States customary units of measure; it is not used in England.
A similar system, termed British Engineering Units by Halliday and Resnick (1974), was a system that used the
slug as the unit of mass, and in which Newton's law retains the form ''F=ma''. Modern British engineering practice has used
SI base unit
The SI base units are the standard units of measurement defined by the International System of Units (SI) for the seven base quantities of what is now known as the International System of Quantities: they are notably a basic set from which all ...
s since at least the late 1970s.
Definition
The English Engineering Units is a system of
consistent units used in the United States. The set is defined by the following units,
with a comparison of
their definitive conversions to their
International System of Units counterparts.
Units for other physical quantities are derived from this set as needed.
In English Engineering Units, the pound-mass and the pound-force are distinct base units, and
Newton's Second Law of Motion takes the form ''F= ma/g
c'', where ''g''
c=32.174lb·ft/(lbf·s
2).
History and etymology
The term
English units strictly refers to the system used in England until 1826, when it was replaced by (more rigorously defined)
Imperial units
The imperial system of units, imperial system or imperial units (also known as British Imperial or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed th ...
. The United States continued to use the older definitions until the
Mendenhall Order of 1893, which established the United States customary units. Nevertheless, the term "English units" persisted in common speech and was adapted as "English engineering units" but these are based on US customary units rather than the pre-1826 English system.
See also
*
Imperial and US customary measurement systems
References
Notes
{{United States Customary Units
Customary units of measurement
Customary units of measurement in the United States