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

With the standard triangular profile the acceleration increases or decreases almost instantaneously, as shown in the acceleration and jerk profile graph at time 0.0, 0.5, and 1.0.

If the velocity-time graph is curved, the acceleration can be found by calculating the gradient of a tangent to the curve.