Some fields of
engineering
Engineering is the use of 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 range of more speciali ...
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
United States customary units form a system of measurement units commonly used in the United States and U.S. territories since being standardized and adopted in 1832. The United States customary system (USCS or USC) developed from English uni ...
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
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a ...
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 al ...
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
The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. ...
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
Newton's laws of motion are three basic Scientific law, laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows:
# A body remains at re ...
takes the form ''F= ma/g
c'', where ''g''
c=32.174lb·ft/(lbf·s
2).
History and etymology
The term
English units
English units are the units of measurement used in England up to 1826 (when they were replaced by Imperial units), which evolved as a combination of the Anglo-Saxon and Roman systems of units. Various standards have applied to English units at ...
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
The imperial and US customary measurement systems are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.
The US Cust ...
References
Notes
{{United States Customary Units
Customary units of measurement
Customary units of measurement in the United States