GTBL042-App-A GTBL042-Callister-v3 September 21, 2007 19:50
AppendixA The International System
of Units (SI)
Units in theInternational System of Unitsfall into two classifications: base and
derived. Base units are fundamental and not reducible. Table A.1 lists the base units
of interest in the discipline of materials science and engineering.
Derived units are expressed in terms of the base units, using mathematical signs
for multiplication and division. For example, the SI units for density are kilogram
per cubic meter (kg/m^3 ). For some derived units, special names and symbols exist;
for example, N is used to denote the newton, the unit of force, which is equivalent to
1 kg-m/s^2. Table A.2 contains a number of the important derived units.
It is sometimes necessary, or convenient, to form names and symbols that are
decimal multiples or submultiples of SI units. Only one prefix is used when a multiple
of an SI unit is formed, which should be in the numerator. These prefixes and their
approved symbols are given in Table A.3. Symbols for all units used in this book, SI
or otherwise, are contained inside the front cover.Table A.1 The SI Base Units
Quantity Name Symbol
Length meter, metre m
Mass kilogram kg
Time second s
Electric current ampere A
Thermodynamic temperature kelvin K
Amount of substance mole mol