---
title: "Speed & Distance-Time Graphs"
description: "Calculate average speed using the equation speed = distance ÷ time, represent journeys on distance-time graphs, and interpret gradient as speed and flat sections as stationary periods"
canonical: https://lightmysky.com/learn/science/speed-and-distance-time-graphs-mt_q-1a86ydgU
source: https://lightmysky.com/learn/science/speed-and-distance-time-graphs-mt_q-1a86ydgU.md
retrieved: 2026-10-19
---

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# Speed & Distance-Time Graphs

Calculate average speed using the equation speed = distance ÷ time, represent journeys on distance-time graphs, and interpret gradient as speed and flat sections as stationary periods

Subject: Science · Area: Forces & Motion · Ages 11 to 12
Page: https://lightmysky.com/learn/science/speed-and-distance-time-graphs-mt_q-1a86ydgU

## Ready when they can

- Uses speed = distance ÷ time to calculate average speed with correct units (m/s, km/h)
- Draws a distance-time graph for a given journey with correct axes and labels
- Reads a distance-time graph to determine speed, stopping points, and direction of travel
- Identifies which section of a distance-time graph represents the fastest speed

## Lesson: Speed and Distance-Time Graphs

Speed tells you how fast something is moving. You work it out with a simple rule: speed = distance ÷ time. If a cyclist travels 20 kilometres in 4 hours, their average speed is 20 ÷ 4 = 5 kilometres per hour (km/h).

*(drawing: In hour 3 the distance covered is 0. That is the lunch stop: time is passing but the rider is not moving.)*

You already know how to read a distance-time graph. Now look closer at the slope, or gradient, of the line. A steep line means the distance is changing fast, so the speed is high. A gentle line means a slower speed. A flat, level line means the distance is not changing at all, so the object is stationary.

**Example.** Mia's distance-time graph shows her walking 6 km in the first 2 hours, then a flat line for 1 hour while she eats lunch, then 4 km more in the next 2 hours. Her fastest section is the first 2 hours, because the line is steepest there. Her overall average speed uses the whole trip: total distance ÷ total time = 10 km ÷ 5 hours = 2 km/h.

**Tip.** Flat does not mean slow, it means stopped. Compare the steepness of different sections to find out which part of a journey was fastest.

**Recap.** Gradient shows speed: steeper means faster, flat means stopped, and average speed always comes from total distance ÷ total time.

## Practice

17 questions on this page, each with its working shown.

## Needs first

- [Compound Units](https://lightmysky.com/learn/mathematics/compound-units-mt_kLQOzZYrd5)
- [Reading Distance-Time Graphs](https://lightmysky.com/learn/science/reading-distance-time-graphs-mt_OUv-QXmW7_)

## Opens up

- [Relative Motion](https://lightmysky.com/learn/science/relative-motion-mt_-OndzpVsrv)
- [Acceleration from Velocity-Time Graphs](https://lightmysky.com/learn/science/acceleration-from-velocity-time-graphs-mt_nmvfbSgnOn)
- [Newton's First & Second Laws](https://lightmysky.com/learn/science/newtons-first-and-second-laws-mt_tXxxCFl32J)