Distance-time graphs

For a moving object, the distance travelled can be represented by a distance-time graph.

A horizontal line on a distance-time graph shows that the object is stationary (not moving), while a sloping line on a distance-time graph shows that the object is moving.

The speed of an object can be calculated from the gradient of a distance-time graph.

curriculum-key-fact
The greater the gradient (and the steeper the line) the faster the object is moving.
A distance time graph shows distance travelled measured by time.

Example

Calculate the speed of the object represented by the green line in the graph, from 0 to 4 s.

change in distance = (8 – 0) = 8 m

change in time = (4 – 0) = 4 s

 speed = \frac{distance}{time}

 speed = 8 \div 4

 speed = 2 \ m/s

Question

Calculate the speed of the object represented by the purple line in the graph.

change in distance = (10 - 0) = 10 m

change in time = (2 - 0) = 2 s

 speed = \frac{distance}{time}

 speed = 10 \div 2

 speed = 5 \ m/s