| English | Derived quantity |
|---|---|
| Bahasa Melayu | Kuantiti terbitan |
| 中文 | 导出物理量 |
Definition
A physical quantity obtained by combining base quantities through multiplication or division, such as speed or density.
In exam terms
A derived quantity is a physical quantity obtained by combining base quantities through multiplication or division. Its unit, a derived unit, is a combination of base units.
For example, speed = distance ÷ time, so its unit is m ÷ s = m s⁻¹. Density = mass ÷ volume gives kg m⁻³.
Some derived units are given special names: force in newton (N), where 1 N = 1 kg m s⁻². A correct sentence: Density is a derived quantity because it is defined as mass per unit volume.
Do not confuse it with base quantity
Do not confuse a derived quantity with a base quantity. A base quantity (length, mass, time, current, temperature) cannot be broken down further, while a derived quantity is always built from base quantities.
In Paper 2, a common task is express the derived unit of a quantity in terms of SI base units. For example, the pascal: pressure = force ÷ area = kg m s⁻² ÷ m² = kg m⁻¹ s⁻².
Show the base-unit working clearly to earn full marks.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)