| English | Base quantity |
|---|---|
| Bahasa Melayu | Kuantiti asas |
| 中文 | 基本物理量 |
Definition
A physical quantity that cannot be defined in terms of other physical quantities; the five in physics are length, mass, time, electric current and temperature.
In exam terms
A base quantity is a physical quantity that cannot be defined in terms of any other physical quantity; it stands on its own. In SPM Physics the five base quantities you must know are length (metre, m), mass (kilogram, kg), time (second, s), electric current (ampere, A) and temperature (kelvin, K).
Every other quantity is built from these. For example, speed is defined from length and time.
A correct exam sentence is: Length, mass and time are three of the base quantities, each with its own SI base unit.
Do not confuse it with derived quantity
Do not confuse a base quantity with a derived quantity. A base quantity is fundamental and needs no other quantity to define it; a derived quantity is obtained by combining base quantities, such as density = mass ÷ volume.
In Paper 2 you may be told to classify a list of quantities into base and derived. A quick test: if the unit is a single SI base unit (m, kg, s, A, K) it is usually a base quantity; if the unit is a combination (m s⁻¹, kg m⁻³) it is derived.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)