Section 15.8

Useful Tables

Table 1a. SI Base Units

¹ "Weight" in common parlance is often used to mean "mass."

Table 1b. SI Supplementary Units

Table 2. Examples of SI Derived Units Expressed in Terms of Base Units

Table 3. SI Derived Units with Special Names

	SI Unit
Quantity	Name	Symbol	Expression in terms of other units
frequency	hertz	Hz	s-1
force	newton	N	m·kg/s2
pressure, stress	pascal	Pa	N/m2
energy, work, quantity of heat	joule	J	N·m
power, radiant flux	watt	W	J/s
electric charge, quantity of electricity	coulomb	C	s·A
electric potential, poetential difference, electromotive force	volt	V	W/A
capacitance	farad	F	c/V
electric resistance	ohm		V/A
electric conductance	siemens	S	A/V
magnetic flux	weber	Wb	V·s
magentic flux density	tesla	T	Wb/m2
inductance	henry	H	Wb/A
Celsius temperature1	degree Celsius	°C	K
luminous flux	lumen	lm	cd·sr
illuminance	lux	lx	lm/m2
activity (of a radionuclide)	becquerel	Bq	s-1
absorbed dose, specific energy imparted, kerma, absorbed dose index	gray	Gy	J/kg
dose equivalent, dose equivalent index	sievert	Sv	J/kg

¹ In addition to the thermodynamic temperature (symbol T) expressed in kelvins (see Table 1a), use is also made of Celsius temperature (symbol t) defined by the equation t=T-T₀ where T₀=273.15 K by definition. To express Celsius temperature, the unit "degree Celsius" which is equal to the unit "kelvin" is used; in this case, "degree Celsius" is a special name used in place of "kelvin." An interval or difference of Celsius temperatures can, however, be expressed in kelvins as well as in degrees Celsius.

Table 4. Examples of SI Derived Units Expressed by Means of Special Names

	SI Unit
Quantity	Name	Symbol
dynamic viscosity	pascal second	PA·s
moment of force	newton meter	N·m
surface tension	newton per meter	N/m
heat flux density, irradiance	watt per square meter	W/m2
heat capacity, entropy	joule per kelvin	J/K
specific heat capacity, specific entropy	joule per kilogram kelvin	J(kg·K)
specific energy	joule per kilogram	J/kg
thermal conductivity	watt per meter kelvin	W/(m·K)
energy density	joule per cubic meter	J/M3
electric field strength	volt per meter	V/m
electric charge density	coulomb per cubic meter	C/m3
electric flux density	coulomb per square meter	C/m2
permittivity	farad per meter	F/m
permeability	henry per meter	H/m
molar energy	joule per mole	J/mol
molar entropy, molar heat capacity	joule per mole kelvin	J/(mol·K)
exposure (x and )	coulomb per kilogram	C/kg
absorbed dose rate	gray per second	Gy/s

Table 5. Examples of SI Derived Units Formed by Using Supplementary Units

Table 6. SI Prefixes

Table 7. Units in Use with the International System

Name	Symbol	Value in SI unit
minute (time)	min	1 min=60 s
hour	h	1 h=60 min=3 600 s
day	d	1 d=24 h=86 400 s
degree (angle)	°	1°=(/180) rad
minute (angle)	'	1'=(1/60)°=(/10 800) rad
second (angle)	"	1"=(1/60)'=(/648 000) rad
1liter	L	1 L=1 dm3=10-3 m3
2metric ton	t	1 t=103 kg
hectare (land area)	ha	1 ha=1 hm2=104 m2
3electronvolt	eV	1eV=1.602 18×10-19 J, approximately
3unified atomic mass unit	u	1 u=1.660 54×10-27 kg, approximately

¹ Both L and l are internationally accepted symbols for liter. Because "l" can easily be confused with the numeral "1," the symbol "L" is recommended for United States use.

² In many countries, this unit is called "tonne."

³ The values of these units expressed in terms of SI units must be obtained by experiment, and are therefore not known exactly. The electronvolt is the kinetic energy acquired by an electron passing through a potential difference of 1 volt in vacuum. The unified atomic mass unit is equal to (1/12) of the mass of the atom of the nuclide 12C.

Table 8. Units in Use Temporarily with the International System

nautical mile	barn	roentgen
knot	bar	rad3
ångström	gal2	rem4
are1	curie

¹ Unit of land area.

² Unit of acceleration.

³ Unit of absorbed dose.

⁴ Unit of dose equivalent.

--Physics Laboratory, National Institute of Standards and Technology

## Useful Tables ##


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