A cyclist starts from rest at point O on a straight horizontal road. The cyclist moves along the road with constant acceleration 2 m/s for 4 seconds and then continues to move along the road at a constant speed. At the instant when the cyclist stops accelerating, a motorcyclist starts from rest at point O and moves along the road with constant acceleration of 4 m/s2 in the same direction as the cyclist. The motorcyclist has been moving for T seconds when she overtakes the cyclist. Find T by sketching a speed-time graph.