Graphs that tell stories
Can a wiggly line tell you the story of a whole journey?
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Explain
A line can show a walk.
Flat means stop, and steep means fast.
A graph turns a journey into a picture. Time goes along the bottom.
On a distance–time graph, a steep line means fast and a flat line means stopped.
On a speed–time graph, a high line means fast. Play the sim and change the speed to draw your own story.
The gradient of a distance–time graph equals the speed: the steeper the line, the higher the speed.
The gradient of a speed–time graph equals the acceleration. The area under a speed–time graph equals the distance travelled.
Worked example: a line rises 30 m in 10 s. Its gradient is 30 / 10 = 3 m/s.
- Walk at a speed
- The graph draws the trip
- Read the story
Want the full story?
A curved distance–time line means the speed is changing, so the gradient is different at each point. To find the speed at one moment, you draw a tangent to the curve. This idea is the start of calculus.
Try it at home
You need paper, a pencil, a ruler.
You need: paper, a pencil, a ruler.
Draw your walk to school as a line.
- Think of a trip with a stop in it.
- Draw axes with time along the bottom and distance up the side.
- Draw the line for your trip.
- Ask someone to tell the story from your graph.
What's happening: every part of the line is one part of the journey. Flat parts show where you stopped.
Physics is life
Your body
A heart monitor draws your heartbeat as a line.
Daily life
Your growth chart is a graph.
Nature
Scientists draw graphs of the weather.
Space
Graphs show how far stars are moving.
Quick check
Question 1 of 3
Words to know
Graph: A picture that shows how one number changes with another.