20 The diagram shows the speed-time graph for 100 seconds of a car’s journey. The car accelerates uniformly from a speed of v m/s to a speed of 3v m/s in 50 seconds. It then continues at a constant speed. (a) Find, in terms of v, the acceleration of the car in the first 50 seconds. (b) The car travels 2500 metres during the 100 seconds. Find v. (c) Find the speed of the car, in kilometres per hour, when t = 75.