Two trains X and Y start simultaneously from stations A and B, which are 600m apart on the same straight track, and move toward each other.
Train X starts from rest and accelerates uniformly at 1m/s2 until it reaches 20m/s, after which it continues at this constant speed.
Train Y moves with a constant speed of 15m/s throughout.
(i) How long does train X take to reach 20m/s?
(ii) After how many seconds from the start will the two trains meet?
(iii) Which train has the greater average speed over the whole journey up to the meeting point?