Acceleration — 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.

Acceleration is the rate of change of velocity, that is, how much the velocity changes each second
Equation:

a = Δv / t = (v − u) / t

where:
- a = acceleration in metres per second squared (m/s²)
- u = initial velocity (m/s)
- v = final velocity (m/s)
- t = time over which the velocity changes (s)
The units of acceleration, m/s², come from "change in m/s, per s", because the velocity changes by a metres per second every second

If the calculated value of a comes out positive, the object is gaining speed in the direction it is already moving (it is accelerating)
If the calculated value of a comes out negative, the object is losing speed; this is called a deceleration
The sign therefore carries physical meaning, because a minus sign in front of an acceleration is the maths telling you the motion is slowing

Worked example

Finding acceleration from a velocity–time graph

A straight line on a velocity–time graph passes through the point (6 m/s, t = 0) and rises to (30 m/s, t = 40 s).

Solution: