| English | Scalar quantity |
|---|---|
| Bahasa Melayu | Kuantiti skalar |
| 中文 | 标量 |
Definition
A physical quantity that has magnitude only, with no direction, such as distance, speed and mass.
In exam terms
A scalar quantity is a physical quantity that has magnitude only, with no direction. It is fully described by a number and a unit.
Examples in SPM include distance, speed, mass, time, temperature, energy and density. Scalars of the same kind are added by ordinary arithmetic: 3 kg + 2 kg = 5 kg, no matter which way the masses point.
A correct sentence: Speed is a scalar quantity because it tells us only how fast an object moves, not the direction.
Do not confuse it with vector quantity
Do not confuse a scalar with a vector quantity, which has both magnitude and direction. Distance is a scalar but displacement is a vector; speed is a scalar but velocity is a vector.
In Paper 2 you may be asked to state whether a quantity is scalar or vector and give a reason. The reason must mention direction: a scalar has magnitude only, while a vector also has a specified direction.
Adding vectors needs geometry, but scalars add directly.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)