Distance-time graphs
A horizontal line on a A graph with distance travelled plotted on the vertical axis against time taken on the horizontal axis. shows that the object is Not moving or at rest. (not moving because the distance does not change)
A sloping line on a distance-time graph shows that the object is moving.
Question
Calculate the speed of the object represented by the green line in the graph, from 0 to 3 s.
Calculate the average speed of the object represented by the green line in the graph, from 0 to 10 s.
Calculate the average speed of the object represented by the purple line in the graph, from 0 to 2 s.
Distance moved = (6 m – 0 m) = 6 m
time taken = (3 s – 0 s) = 3 s
speed = gradient of distance-time graph = distance moved Ă· time taken
speed = 6 m Ă· 3 s = 2 m/s
The total distance travelled by the vehicle on the green line is 7 m.
The time taken to travel this distance is 10 s.
Average speed = total distance moved Ă· time taken = 7 m Ă· 10 s = 0.7 m/s.
The speed of the object represented by the purple line can also be calculated.
distance moved = (10 m – 0 m) = 10 m
time taken = (2 s – 0 s) = 2 s
speed = gradient of distance-time graph = distance moved Ă· time taken
speed = 10 m Ă· 2 s = 5 m/s