What the line tells you

Time goes along the bottom, distance goes up the side. Every point is "at this time, it had gone this far".

  • O to A: steep line, moving fast.
  • A to B: flat line, distance not changing, so stationary.
  • B to C: shallower line, moving more slowly.

Gradient is speed

The gradient of a distance-time graph is the speed. Pick two points on a straight section:

  1. gradient = change in distance ÷ change in time
  2. O to A: 40 m ÷ 20 s = 2 m/s
  3. B to C: (60 − 40) m ÷ (60 − 35) s = 20 ÷ 25 = 0.8 m/s

A curved line means the speed is changing. Getting steeper: speeding up. Getting flatter: slowing down. For the speed at one moment on a curve, draw a tangent (a straight line that just touches the curve) and find its gradient. That is in the Plus questions for this lesson.

Read it off the graph

Go up from the time to the line, then across to the distance axis. A ruler helps on paper; here, follow the grid lines.