Two trains of length 200 m and 325 m long are running on parallel rail tracks at speeds of 78 km/h and 60 km/h, respectively. In how much time (in seconds) the faster train cross the slower one if they are running in the same direction?

Speed of the faster train=78×5/18 =390/18=21.67m/sec. Speed of slower train =60×5/18 =300/18 =16.67m/sec Since the trains are moving in the same direction, the relative speed is the difference between their speeds: Relative speed. = 21.67 m/s -16.67 m/s = 5 m/s The total distance to be covered is the sum of the lengths of the two trains: Total distance = 200 m + 325 m =525 m Time taken to cross Total distance Relative speed. =525 m /5 m/s Time = 105 seconds