Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km h–1 in the same direction, with A ahead of B. The driver of B decides to overtake A and accelerates by 1 m s–2. If after 50 s, the guard of B just brushes past the driver of A, what was the original distance between them?
Given that, uA=uB=72kmh−1=72×185=20ms−1 Using the relations, s=ut+21at2, we get SB=uBt+21at2=20×50+21×1×(50)2 SB=1000+1250=2250m Also, let SA be the distance covered by the train A, then SA=uA×t =20×50=1000m Original distance between the two trains = SB−SA =2250−1000=1250m
