APPENDIX A

The International System of Units

The International System of Units(SI), uses a single basic unit for each physical quantity, and multiples and fractions of this unit are formed by adding a prefix. For example, the SI unit for length is the meter (m). The millimeter (mm), centimeter (cm), and kilometer(km) are formed by adding the prefixes milli- (m), centi- (c), and kilo- (k) to meter. The same prefixes are used for all physical quantities. The prefixes and their symbols are listed in Table A.1.

The following rules should be observed when using SI symbols of units:

• Do not put a period after a symbol. Therefore, 7 km. is incorrect, but 7 km is correct.
  
• Do not put s at the end of any symbol. Therefore, 7kms is incorrect, but 7 km is correct.
  
• The symbol for a unit is a lowercase letter except when the unit is derived from a proper name(i.e. Newton, Pascal, Joule etc.). Thus, the symbol for the meter is m, whereas the symbol for the Newton is N. (An exception is the symbol for L for liter.)
  
• A symbol with the prefix is treated as a new unit which can be raised to a power without using brackets. Thus, the notation means , and not .
  
  
  

Prefix	Symbol	Value
tera-	T
giga-	G
mega-	M
kilo-	k
hecto-	h
deca-	da
deci-	d
centi-	c
milli-	m
micro-
nano-	n
pico-	p
femto-	f
atto-	a

Quantity	Name of Unit	Symbol of Unit	Unit(with Fundamental Units)
Frequency	Hertz	Hz
Force	Newton	N
Pressure	Pascal	Pa
Energy	Joule	J
Power	Watt	W
Electric charge	Coulomb	C
Electric potential	Volt	V
Electric resistance	Ohm
Electric capacitance	Farad	F
Magnetic filed	Tesla	T
Magnetic flux	Weber	W

Unit	Conversion Units
1 degree
1 revolution
1 meter	3.281ft=39.37in.
1 light year
1 kilogram	2.205lb=35.27oz
1 atomic mass unit
1 slug	14.59kg
1 cubic meter
1 joule