| English | Velocity |
|---|---|
| Bahasa Melayu | Halaju |
| 中文 | 速度 |
Definition
The rate of change of displacement with time; a vector quantity, measured in metres per second (m s⁻¹).
In exam terms
Velocity is the rate of change of displacement with time. It is a vector, symbol v, SI unit the metre per second (m s⁻¹), calculated as velocity = displacement ÷ time.
For example, if a runner covers a displacement of 100 m due north in 20 s, the velocity is v = 100 m ÷ 20 s = 5 m s⁻¹ due north. Uniform velocity means the object moves in a straight line covering equal displacements in equal time intervals, so both its speed and direction stay constant.
Do not confuse it with speed
Do not confuse velocity with speed. Speed is a scalar (distance ÷ time, magnitude only); velocity is a vector (displacement ÷ time, with direction).
A car going round a bend at a steady 60 km h⁻¹ has constant speed but changing velocity, because its direction keeps changing.
In Paper 2 this is asked as state the difference between speed and velocity, or calculate the velocity from a displacement-time graph (its gradient), so include the direction when the question expects a vector.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)