IGCSE Maths / Travel and other graphs
Reading a distance-time graph
Edexcel International GCSE Maths (4MA1), chapter 10: Travel and other graphs, specification point 3.3a-f. Free lesson.
Read the revision notes · IGCSE Maths past papers
A distance-time graph shows how an object's distance from its starting point changes over time. Its shape tells you whether the object is moving away, stopped or returning, while its steepness shows its speed.
What the shape of a line tells you
Read the line from left to right as time passes. The steepness shows speed, while whether the line rises or falls shows how the distance from the start is changing. A line sloping up means distance is increasing, so the object is moving away from the start. A steeper slope means more distance is covered in the same time, so the object is going faster. A flat line means the distance is not changing, so the object is stopped. A slow journey has a shallow slope that still rises. A line sloping down means the distance from the start is decreasing, so the object is returning towards the start.…
How to find speed from a journey
The steepness of a distance-time graph represents speed, because speed is the distance travelled divided by the time taken. Use the distance and time for the section of the journey you are asked about.
How to read a journey with a stop and return
Treat each part of the journey separately. A flat section adds time but no distance travelled away from the start. Add the times for the outward journey, the stop and the return to find the total time. The outward speed is found from the rising section. The object is stopped during the flat section. A falling section shows the object getting closer to its starting point.
How to use minutes when finding speed
For a speed in kilometres per hour, the time must be in hours. Convert minutes before dividing, or the speed will be calculated using the wrong time unit.