AS Physics : Base and derived units
Physics is the science of the material world, and one of its main
components is the measurement of aspects of that world. Every
measurement involves the usage of a unit; it is this part of the
measurement that defines what the numbers refer to. All units
may be simplified down so that they are made up of one or
several base units. The quantities that these units describe are
the fundamental quantities of physics – all quantities can be
defined in terms of these seven units. In the case of each base
unit, there are alternative scales that may be used (e.g. Celsius
or Fahrenheit as opposed to Kelvin for temperature), but uses of
these alternatives are limited. The names and symbols
described below are known as SI units – they are recognised
and standardised around the world.
Base and Derived Units
Base
Derived
Metres - m
Coulomb - C
Amperes - A
Volt - V
Kelvin – K
Newton - N
Kilogram - kg
Pascal - Pa
Second – s
Watt - W
Candela – cd
Ohm - Ω
Mole - mol
Joule - J
Unit Prefixes
Power
109
106
103
10-3
10-6
10-9
10-12
Prefix
giga
Mega
Kilo
milli
micro
nano
pico
Symbol
G
M
k
m
μ
n
p
The unit for a particular measurement can easily be
substantiated from the equation. The equation can be arranged,
then simplified, before substituting in the units for their
corresponding symbols left in the simplified equation.
Work out the base units for the derived units given in the table
above.
GJ2008.