| English | SI unit |
|---|---|
| Bahasa Melayu | Unit SI |
| 中文 | 国际单位 |
Definition
The internationally agreed system of units for physical quantities, based on the seven SI base units such as the metre, kilogram and second.
In exam terms
The SI unit system (Systeme International) is the internationally agreed set of units for physical quantities. It is built on seven base units, of which SPM uses five: metre (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for current and kelvin (K) for temperature.
All other units, called derived units, come from these, such as m s⁻¹ and the newton (N). Using SI units lets scientists everywhere compare results.
A correct sentence: The SI unit of force is the newton, where 1 N = 1 kg m s⁻².
Do not confuse unit with quantity
Do not confuse an SI unit with the physical quantity it measures. The metre is a unit; length is the quantity.
Also do not confuse SI base units with derived units: the second is a base unit, while the pascal is derived.
In Paper 2 you may be told to state the SI base unit of a quantity, or to convert to SI units before substituting into a formula (for example, cm to m). Always convert to SI units first, or the numerical answer will be wrong.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)