25 The diagram is the speed-time graph of a cyclist. The cyclist accelerates uniformly from a speed of u metres per second to a speed of 3u metres per second in a time of 10 seconds. (a) Find an expression, in terms of u, for the acceleration. (b) The distance travelled by the cyclist from t = 0 to t = 10 is 40 m. (i) Find the value of u. (ii) On the grid below, sketch the distance-time graph of the cyclist.