
Units

Measurement is at the heart of science. Without measurements
to support or reject a hypothesis, science is simply conjecture
 no better than crsytal balls and magic potions. many things
can be measured: Consider any object, we can measure its

 and so on. The measurement of most quantities have units
attached to them. howeverm the matter is compicated by the fact
that several units can describe the same quantity, e.g., we can
measure length by inches, centimeters, meters, yards, kilometers,
miles etc. in order to aviod worldwide confusion, scientists
decided to settle on a certain set of units to express basic
quantities  the socalled fundamental units

 The Fundamental Units
Mass  kilogram (kg)
Length  meter (m)
Time  second (s)
Temperature  Kelvin (K)
Charge  Coulomb (C)


 All other units are combinations
of these units and are called "derived" units.

quantity 
unit 
SI 
speed 
length 
m/s 
volume 
length+3 
m+3 
energy 
mass length2/time2 
kg m2/s2 
density 
mass/volume 
kg/m3 
force 
mass length/time2 
kg m/s2 
pressure 
mass/length time2 
kg/m s2 

 Volume is an especially important
quantity since it can be readily measured. Volume always has
the units of a cubic length. the relationship between m3, dl
and ml (cc) is readily understood from the diagram below

