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SI base units
The SI is founded on seven
SI base units
for seven
base quantities
assumed to
be mutually independent, as given in Table 1.
For detailed information on the SI base units, see
Definitions of the SI base
units
and their
Historical context
.
SI derived units
Other quantities, called
derived quantities
, are defined in terms of the seven
base quantities via a system of quantity equations. The
SI derived units
for
these derived quantities are obtained from these equations and the seven SI
base units. Examples of such SI derived units are given in Table 2, where it
should be noted that the symbol 1 for quantities of dimension 1 such as mass
fraction is generally omitted.
Table 1.
SI base units
Base quantity
Name
Symbol
SI base unit
length
meter
m
mass
kilogram
kg
time
second
s
electric current
ampere
A
thermodynamic temperature
kelvin
K
amount of substance
mole
mol
luminous intensity
candela
cd
Derived quantity
Name
Symbol
Table 2.
Examples of SI derived units
SI derived unit
area
square meter
m
2
volume
cubic meter
m
3
speed, velocity
meter per second
m/s
Page 1 of 5
12/12/2007
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View Full Documentacceleration
meter per second squared
m/s
2
wave number
reciprocal meter
m
1
mass density
kilogram per cubic meter
kg/m
3
specific volume
cubic meter per kilogram
m
3
/kg
current density
ampere per square meter
A/m
2
magnetic field strength
ampere per meter
A/m
amountofsubstance concentration
mole per cubic meter
mol/m
3
luminance
candela per square meter
cd/m
2
mass fraction
kilogram per kilogram, which
may be represented by the
number 1
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 Spring '08
 Lee
 SI base unit, International System of Units, Physical quantities, SI derived unit, si base units

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