Base Quantities
- Physical quantities are quantities that can be measure.
- Each physical quantity contains information on its numerical magnitude and unit of measurement.
- Physical quantities can be classified into two types,
- the base quantities
- the derived quantities
- Base quantities are quantities that cannot be defined in terms of other base quantities.
- A base unit is the unit of a base quantity.
- The following shows the 6 base quantities and the base units.
\[ \begin{array}{|c|c|c|} \hline \text { Quantity } & \text { Name of unit } & \text { Unit symbol } \\ \hline \text { Length } & \text { metre } & m \\ \hline \text { Mass } & \text { kilogram } & kg \\ \hline \text { Time } & \text { second } & s \\ \hline \text { Electric current } & \text { ampere } & A \\ \hline \begin{array}{c} \text { Thermodynamic } \\ \text { temperature } \end{array} & \text { Kelvin } & K \\ \hline \text { Amount of substance } & \text { mole } & mol \\ \hline \end{array} \]
Derived Quantities
- Derived quantities are physical quantities derived from a combination of various base quantities through multiplication or division.
- For example, the area of a rectangle = Width x Length. Both width and length are base quantities, whereas area is a derived quantity as it is derived from length.
- A derived unit is the unit of a derived quantity. It is the product and/or quotient of the base units.