Modern Engineering Thermodynamics

16 CHAPTER 1: The Beginning
Table 1.4 Some Common Derived SI Units
Dimension Name Symbol Formula Expression in Terms of SI Fundamental Units
Frequency hertz Hz 1/s s –1
Force newton N kg·m/s 2 m·kg·s –2
Energy joule J N·m
–2
m
2·kg·s
Power watt W J/s
–3
m
2·kg·s
Electric charge coulomb C A·s A·s
Electric potential volt V W/A
–1
m
2·kg·s
–3·A
Electric resistance ohm Ω V/A
–2
m
2·kg·s
–3·A
Electric capacitance farad F C/ V
2
m
–2·kg
–1·s
4·A
Magnetic flux weber Wb V·s
–1
m
2·kg·s
–2·A
Pressure or stress pascal Pa N/m 2 –2
m
–1·kg·s
Conductance siemens S A / V
2
m
–2·kg
–1·s
3·A
Magnetic flux density tesla T Wb/m 2 –1
kg·s
–2·A
Inductance henry H Wb/A m 2·kg·s –2· A –2
Luminous flux lumen lm cd·sr cd·sr
Illuminance lux lx lm/m 2 m –2·cd·sr
Source: Adapted from the American Society for Testing and Materials, 1980. Standard for Metric Practice, ASTM 380-79. Copyright ASTM.
Reprinted with permission. ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428.
Table 1.5 SI Unit Prefixes
Multiples Prefixes Symbols
10 18 exa E
10 15 peta P
10 12 tera T
10 9 giga G
10 6 mega M
10 3 kilo k
10 2 hecto h
10 0 — —
10 1 deka da
10 –1 deci d
10 –2 centi c
10 –3 milli m
10 –6 micro μ
10 –9 nano n
10 –12 pico p
10 –15 femto f
10 –18 atto a
Source: Adapted with permission from the American Society for Testing and Materials, 1980.
Standard for Metric Practice, ASTM 380-79. ASTM International, 100 Barr Harbor Drive,
PO Box C700, West Conshohocken, PA 19428.
appear at the beginning of a sentence) regardless of whether they were derived from proper names or not. Therefore
the name of the SI absolute temperature unit was reduced from degree Kelvin to simply kelvin even though
the unit was named after Lord Kelvin. However, when the name of a unit is to be abbreviated, it was decided
that the name abbreviation was to be capitalized if the unit was derived from a proper name. Therefore, the kelvin absolute
temperature unit is abbreviated as K (not °K, k, or °k). Similarly, the SI unit of force, the newton, named
after Sir Isaac Newton (1642–1727), is abbreviated N. The following list illustrates a variety of units from the SI
and other systems, all of which were derived from proper names:
ampere (A), becquerel (Bq), celsius (°C), coulomb (C), farad (F), fahrenheit (°F), gauss (G), gray (Gy), henry (H),
hertz (Hz), joule (J), kelvin (K), newton (N), ohm (Ω), pascal (Pa), poiseuille (P), rankine (R), siemens (S), stoke (St),
tesla (T), volt (V), watt (W), weber (Wb).