I am trying to model a situation in which a car passes the point A on a straight road with a speed of 10 m/s, and moves with a constant acceleration of a m/s^2 along the road for T seconds until it reaches the point B where its speed is V m/s. The car is then travelling at this speed (V) for a further 10 seconds when it reaches a point C. From C it travels for a further T seconds with a constant acceleration 3a m/s^2, until a speed of 20 m/s is reached at a point D. The question being asked is to show that V = 12.5 m/s. However, I feel as if I am doing the graph wrong. Here is what my graph looks like:
Is this graph ok, and if so what do I need to do in order to find V, because I have been trying to use three SUVAT equations as there are three variables (which means I need three equation to solve simultaneously) to get V, a and T, however, I haven't really made any progress. Is there a way to find a solution using the graph?