|
2-acoustic ohm |
cgs unit of
acoustic impedance (the ratio of sound pressure on a
surface to sound flux through the surface) |
|
3-acre |
traditional
English land measure; 1 acre = 4,480 sq yd (4,047 sq
m or 0.4047 ha) |
|
4-acre-foot |
unit sometimes
used to measure large volumes of water such as
reservoirs; 1 acre-foot = 1,233.5 cu m/43,560 cu ft |
|
5-astronomical
unit |
unit (symbol AU)
equal to the mean distance of the earth from the
sun: 149,597,870 km/92,955,808 mi |
|
6-atmosphere |
unit of pressure
(abbreviation atm); 1 standard atmosphere = 101,325
Pa |
|
7-barn |
unit of area,
especially the cross-sectional area of an atomic
nucleus; 1 barn = 10-28 sq m |
|
8-barrel |
unit of liquid
capacity; the volume of a barrel depends on the
liquid being measured and the country and state
laws. In the United States, 1 barrel of oil = 42 gal
(159 l/34.97 imperial gal), but for federal taxing
of fermented liquor (such as beer), 1 barrel = 31
gal (117.35 l/25.81 imperial gal). Many states fix a
36-gallon barrel for cistern measurement and federal
law uses a 40-gallon barrel to measure “proof
spirits.” 1 barrel of beer in the UK = 163.66
l (43.23 U.S. gal/36 imperial gal) |
|
9-base box |
imperial unit of
area used in metal plating; 1 base box = 20.232 sq
m/31,360 sq in |
|
10-baud |
unit of
electrical signaling speed equal to 1 pulse per
second |
|
11-brewster |
unit (symbol B)
for measuring reaction of optical materials to
stress |
|
British thermal
unit |
imperial unit of
heat (symbol Btu); 1 Btu = approximately 1,055 J |
|
12-bushel |
measure of dry
and (in the UK) liquid volume. 1 bushel (struck
measure) = 8 dry U.S. gallons (64 dry U.S. pt/35.239
l/2,150.42 cu in). 1 heaped U.S. bushel = 1.278
bushels, struck measure (81.78 dry pt/45.027
l/2,747.715 cu in), often referred to as 1¼ bushels,
struck measure. In the UK, 1 bushel = 8 imperial
gallons (64 imperial pt); 1 UK bushel = 1.03 U.S.
bushels |
|
13-cable |
unit of length
used on ships, taken as 1/10 of a nautical mile
(185.2 m/607.6 ft) |
|
14-calorie |
cgs unit of heat,
now replaced by the joule; 1 calorie = 4.1868 J |
|
15-carat |
unit for
measuring mass of precious stones; 1 carat = 0.2
g/0.00705 oz |
|
16-carat |
unit of purity in
gold; pure gold is 24-carat |
|
17-carcel |
obsolete unit of
luminous intensity |
|
18-cental |
name for the
short hundredweight; 1 cental = 45.36 kg/100 lb |
|
19-chaldron |
obsolete unit
measuring capacity; 1 chaldron = 1.309 cu m/46.237
cu ft |
|
20-clausius |
in engineering, a
unit of entropy; defined as the ratio of energy to
temperature above absolute zero |
|
21-cleanliness
unit |
unit for
measuring air pollution; equal to the number of
particles greater than 0.5 μm in diameter per cu
ft of air |
|
22-clo |
unit of thermal
insulation of clothing; standard clothes have
insulation of about 1 clo, the warmest have about 4
clo per 2.5 cm/1 in of thickness |
|
23-clusec |
unit for
measuring the power of a vacuum pump |
|
24-condensation
number |
in physics, the
ratio of the number of molecules condensing on a
surface to the number of molecules touching that
surface |
|
25-cord |
unit for
measuring the volume of wood cut for fuel; 1 cord =
3.62 cu m/128 cu ft, or a stack 2.4 m/8 ft long, 1.2
m/4 ft wide and 1.2 m/4 ft high |
