Speed Time Graphs: Distance

Things often change speed, so speed-time graphs can be more complicated:

The average speed can be used to find the distance travelled:

Average speed = (10 + 30) / 2 = 20 m/s
Distance = average speed × time
Distance = 20 × 20 = 400 m

Alternatively, the area may be found underneath the line:

Blue rectangle = 20 × 10 = 200 m
White triangle = (20 × 20) / 2 = 200 m
Total distance = 200 + 200 = 400 m
Both methods give the same result, as we should expect! Use whichever you find easiest.

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