Two trains having lengths of 110 m and 390 m are running at speeds of 120 km/h and 130 km/h, respectively, in the same direction. The time taken (in minutes) by the faster train, coming from behind, to completely cross the other train is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 3 .
Lengths = 110 m and 390 m
Speeds = 120 km/h and 130 km/h
Relative speed = 130 − 120 = 10 km/h = 10 × 5/18 = 25/9 m/s
Distance to cross = 110 + 390 = 500 m
Time in seconds = 500 ÷ (25/9) = 500 × 9/25 = 180 s
Time in minutes = 180 ÷ 60 = 3 minutes