Gradient = rate of change
On a distance–time graph the gradient is the speed; on a speed–time graph the gradient is the acceleration. A flat (horizontal) line means "stationary" (distance–time) or "constant speed" (speed–time).
Area under a speed–time graph = distance
Split the area into rectangles and triangles. A rectangle is speed × time; a triangle is base height.
speed = distance ÷ time
Rearrange as needed: , . Keep units consistent.
Drawn from real examiner reports.
Reading coordinates by counting squares, not the scale
A point was read as because it was "1 square along, 4 squares up" — but each square was not one unit, so the true values were different. Always use the axis scale.
Treating times like 9 h 36 min as 9.36
h min is h (since ), not . Convert minutes to a fraction of an hour first.
Using the wrong speed–distance–time arrangement
Writing instead of , or dividing the wrong way round.
Describe each segment by its gradient
Going up = speeding up / moving away; flat = constant; coming down to 0 on a speed–time graph = decelerating to rest. Read the gradient of each straight section in turn.
Formula linking speed, distance and time?
On a speed–time graph an object speeds up uniformly from to m/s in s. Find its acceleration (the gradient).
