Measurement

Metric and The International System of Units (SI)

  • The International System of Units (also known as the SI system) defines fundamental quantities for mass, distance, time, and temperature, among others. These quantities are based on seven defining constants such as the speed of light and the charge of an electron.  All other quantities are derived from these by factors of 10.  

SI System Units

  • Length = Meter (M)

  • Volume = Cubic Meter (M³)

  • Mass = Kilogram (KG)

  • Time = Second (S)

  • Temperature = Kelvin (K)

Centimeter, Gram, Second (cgs System)

  • For measurements of objects and volumes we would use every day, the cgs* system is more practical. 

  • CGS System Units

    • Length = Centimeter (CM)

    • Mass = Gram (G)

    • Time = Second (S)

    • Temperature = Kelvin (K)

    • Prefix

      Symbol

      Meaning

      Order of Magnitude

      Giga-

             G

      1 000 000 000

      10^9

      Mega-

             M

      1 000 000

      10^6

      Kilo-

              k

      1 000

      10^3

      Hecto-

              h

      1 00

      10^2

      Deka-

            da

      1 0

      10^1

       

      Base Unit

      1

      10^0

      Deci-

             d

      0.1

      10^-1

      Centi-

             c

      0.01

      10^-2

      Milli-

            m

      0.001

      10^-3

      Micro-

             μ

      0.000 001

      10^-6

      Nano-

             n

      0.000 000 001

      10^-9

    • The base units are meter for length, gram for mass, and liter for volume, but it could be anything.  We could have a kiloinch which would mean that we have 1000 inches. A milliday is one thousandth (1/1000) of a day.