Scientific Notation

Table 4. Some common units defined in terms of SI units
Quantity Name of unit Unit symbol Definition of unit
length inch in. 2.54 x 10–2 m
mass pound (avoirdupois) lb 0.45359237 kg
force kilogram-force kgf 9.80665 N
pressure atmosphere atm 101325 Pa
pressure torr torr (101325/760) Pa
pressure conventional millimeter of mercury* mmHg 13.5951 x 980.665 x 10–2Pa
energy kilowatt-hour kWh 3.6 x 106 J
energy thermochemical calorie cal 4.184 J
energy international steam table calorie cal 4.1868 J
thermodynamic temperature (7) degree Rankine ° R (5/9) K
customary temperature (t) degree Celsius °C t(°C) = T(K) – 273.15
customary temperature (t) degree Fahrenheit °F t(°F) = T(°R) – 459.67
radioactivity curie Ci 3.7 x 1010 Bq
energy† electronvolt eV eV = l .60218 x 10–19 J
mass† unified atomic mass unit u u = 1.66054 x 10–27 kg
*The conventional millimeter of mercury, symbol mmHg (not mm Hg), is the pressure exerted by a column exactly 1 mm high of a fluid of density exactly 13.5951 g cm–3 in a place where the gravitational acceleration is exactly 980.665 cm s–2 The mmHg differs from the torr by less than 2 × 10–7 torr.
 
†These units defined in terms of the best available experimental values of certain physical constants may be converted to Sl units. The factors for con version of these units are subject to change in the light of new experimental measurements of the constants involved.