Reading Distance-Time Graphs
Read and plot distance-time graphs for moving objects; interpret the gradient (steepness) of a line as speed; identify stationary periods (horizontal sections), constant speed (straight diagonal lines), and relative speeds by comparing gradients; calculate average speed from the gradient of a straight-line segment using speed = distance ÷ time
What a learner can do afterwards
- Read a distance-time graph and describe what is happening at each stage — moving, stopped, returning
- Calculate speed from the gradient of a straight section of a distance-time graph
- Sketch a distance-time graph from a written description of a journey with stops and speed changes
The lesson
A distance-time graph shows how far something has traveled as time passes. Time runs along the bottom. Distance goes up the side. Reading the line from left to right tells you the story of a journey.
The steepness of the line is called the gradient, and the gradient tells you the speed. A steep line means a lot of distance covered in a short time, so the object was moving fast. A gentle line means it was moving slowly.
Zara's line rises from 0 to 100 meters over 20 seconds. Her speed is distance divided by time: 100 divided by 20 equals 5 meters per second. If the next part of the line is flatter than that, she has slowed down.
When comparing two lines, the steeper one always shows the faster speed, even if it starts lower down on the graph.
A steeper line means a faster speed, a flat line means the object has stopped, and speed always comes from distance divided by time.
Watch it
Where it sits
Learn first
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.