Key fact The gradient of speed-time and velocity-time graphs represent acceleration. The area under a speed-time graph represents the distance travelled.

Example The velocity of a sledge as it slides down a hill is shown in the graph. Find the acceleration of the sledge when t = 6 s.

A graph of Jupiter’s apparent velocity against time would therefore slope down so that the area under the curve forms a trapezoid – a four-sided shape with a sloping top.