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Length, circumference, diameter, volume, mass, duration, population, etc are called physical quantity..
Length, circumference, diameter, etc. are physical quantities.
A physical quantity is a characteristic that allows the numerical comparison of two identical physical quantities. Each quantity can be assigned a value.
The term quantity is defined in DIN 1313:198-12. Further information in Wikipedia: https://en.wikipedia.org/wiki/Physical_quantity
The term “characteristic” is defined in DIN 55350-12. The characteristic is a property to which a value can be assigned using objective methods, for example through measurement. The terms characteristic and quantity have similar meanings. The postal code, for example, is a characteristic, but not a quantity, because comparing the quantity or ratioing two postal codes makes no sense.
The value of a quantity is determined by a numerical value and a unit. For many units, special unit symbols are agreed upon in DIN 1301.
Examples: The units of “length” include meters (m), centimeters (cm). Units of "mass" are, for example, kilograms (kg) or grams (g).
https://en.wikipedia.org/wiki/Unit_of_measurement
The physical quantities "length" (l), thickness (t), distance (s), circumference (u) belong to the same dimension "length" with the unit meter (m).
The dimension describes the qualitative properties of a physical quantity, while the numerical value and unit describe the quantitative properties of a dimension.
The international SI system of units consists of 7 base units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol) and candela (cd) and all units derived therefrom. The SI system of units is a coherent system of units because all units can be derived by products of Zener powers of the base units.
Dimension | Symbol of quantity | Symbol of Dimension | Base Unit | Symbol of unit |
---|---|---|---|---|
Length | l | L | Meter | m |
Mass | m | M | Kilogram | kg |
Time | t | T | Second | s |
Current | i | I | Ampere | A |
Temperature | T | Θ | Kelvin | K |
Amount of substance | n | N | Mol | mol |
Luminous intensity | lv | J | Candela | cd |
Vorsätze (Einheitenvorsätze, Präfixe) werden eingesetzt, um Vielefache oder Teile von Maßeinheiten zu bilden und dadurch Zahlen mit vielen Vor- oder Nachkommastellen zu vermeiden.
Symbol | Prefix | Power of ten | Value | Name |
---|---|---|---|---|
G | Giga | 109 | 1.000.000.000 | Milliarde |
M | Mega | 106 | 1.000.000 | Million |
k | kilo | 103 | 1.000 | Tausend |
100 | 1 | Eins | ||
m | Milli | 10-3 | 0.001 | Tausendstel; Promille |
µ | Mikro | 10-6 | 0.000001 | Millionstel; ppm |
n | Nano | 10-9 | 0.000000001 | Milliardstel |