Thread: A lift travels vertically upward from rest at floor A to rest at floor B, which is

20m above A, in three? stages as follows:
Firstly, the lift accelerates from rest at A at 2m/s^2 for 2 seconds; secondly, it travels at a constant speed, thirdly, it slows down uniformly at 4m/s^2 coming to rest at B.

Sketch the velocity-time graph for this motion, and show that the journey from A to B takes 6.5 seconds.