Base units
Square metres, cubic metres
 
1 . International System base units.

In Physics there are different physical properties: force, power, energy, pressure, temperature, speed, electrical potential, resistance, electrical charge, time, luminous intensity...
Each of them has a corresponding unit or units, but if there was a different unit for each physical property, the list of units would be very long. However, as the physical properties are related among them, only seven base units have been established. The remaining units can be defined upon these seven units.
Magnitude Unit Symboly
length metre m
mass kilogramme kg
time second s
electrical current ampere A
thermodynanic temperature kelvin K
quantity of matter mole mol
luminous intensity candela cd

You have already studied some of them, and you are going to study the others in the next academic years.
Each of these seven units has been defined scientifically, specified in such a way that it is not based on a standard which can deteriorate. The kilogramme is defined according to the cylinder of platinum and iridium kept in the International Bureau of Weights and Measures in Paris.
The unit symbols are written in small letters, except those symbols that come from a proper noun.
         
           
  Eduardo Barbero Corral
 
Spanish Ministry of Education. Year 2007
 
 

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