Speed — Movement & Position | IGCSE Physics

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 12% of your exam marks.

stable

High

Stable12%

Distance-time graphs, speed calculations and velocity appear in nearly every series.

What speed measures

Speed is the distance an object travels each second
Speed is a scalar quantity: it has a magnitude (a numerical size) but no direction
The SI unit is metres per second (m/s); other units include km/h and mph for everyday contexts
An object's speed is rarely truly constant from second to second; in most real journeys the instantaneous speed drifts as the motion progresses

Average speed

smooths the whole journey into one figure that ignores the moment-by-moment variation:

average speed = (total distance moved) / (total time taken)

The same equation rearranges three ways:
- distance = average speed × time
- time = distance / average speed

Exam tip

Stating and using the average speed formula

What comes up: a question asks you to state the formula linking average speed, distance and time, then use it to find a value.

Write (two marks): (1) average speed = distance moved ÷ time taken (standard symbols such as v = s/t are accepted); (2) substitute correct values and evaluate, giving the answer in m/s.

Watch out: the mark scheme accepts s or d for distance and v or s for speed — use whatever symbol you write consistently. If the question data are in km and hours, convert first: dividing kilometres by hours gives km/h, not m/s.