- For the distance, the meter (m).
- For mass, the kilogram (Kg).
- For temperature, the degree centigrade (° C).
- For the electric charge, the Coulomb (C).
- For time, the second (s).
- For amount of substance, the mole (mole).
- For light intensity, the candela (Cd).
However, to represent more complex properties and phenomena, several of the fundamental units are combined with each other , creating the so-called Derived Units .
Where do derived units come from?
Derived units result from the union of two or more fundamental units . This happens when one quantity affects another, as in the following examples:
- The pressure (P) is the force exerted on an area (F / A), so it is expressed as a ratio of the units of force between those of the area: Newton square meter (N / m 2 ), units finally they are united in a new Pascal call (Pa) , a unit with its own symbol (Pa = N / m 2 ).
- The density ( ρ) is the mass in each unit volume (m / V), so is expressed as a ratio of the mass units between volume: kg on cubic meter (kg / m 3 ) , units that are thus represented.
- The electric current (I) is an electric charge (Q) that flows for each unit of time (t), (Q / t) so it is expressed as a quotient of the units of electric charge and those of time: Coulomb over second (C / s), units that are finally united in a new call Ampere (A) , a unit with its own symbol (A = C / s).
- The velocity (v) indicates how much distance or length (d) traverses an object or a substance per unit time (t), (d / t), so is expressed as a ratio of the distance units between the time: meters over second (m / s) , units that are thus represented.
- The volumetric flow or flow (q) is the volume (V) of a substance that passes from one point to another in a pipe, for example, for each unit of time (t), (V / t), so it is expressed as a ratio of the units of volume between those of time: cubic meters over second (m 3 / s) , units that are thus represented.
To get a derived unit, all you have to do is take a good look at the magnitudes involved in which you want to represent, how they are related to each other and how they are affected, whether by adding, subtracting, multiplying or dividing.
20 examples of derived units
- Area (A): square meter (m 2 )
- Volume (V): cubic meter (m 3 )
- Force (F): Newton (N) = kilogram-meter between second squared (Kgm / s 2 )
- Pressure (P): Pascal (Pa) = Newton between square meter (N / m 2 )
- Density (ρ): kilogram per cubic meter (kg / m 3 )
- Specific volume ( v ): cubic meter between kilogram (m 3 / kg)
- Electric current (I): Ampere (A) = Coulomb per second (C / s)
- Electric potential or voltage (V): Volt (V) = Joule / Coulomb (J / C)
- Work (W): Joule (J) = Newton-meter (Nm)
- Flow or volumetric flow (q): cubic meters per second (m 3 / s)
- Speed (v): meter between seconds (m / s)
- Acceleration (a): meter per second squared (m / s 2 )
- Power (W / t): watt or Joule between seconds (J / s)
- Specific heat (Ce): calories between gram and degree centigrade (cal / g ° C)
- Mass flow (m̅): kilogram between seconds (Kg / s)
- Frequency: Hertz (Hz) = once every second (1 / s)
- Brightness: candela between square meter (Cd / m 2 )
- Molar concentration or molarity (M): Moles per liter (mol / L)
- Molal concentration or molality (m): moles per 1000 g of solvent (mol / 1000g)
- Mass concentration: kilograms solute between kilograms solvent (Kg / Kg)