Question

Two trains, one 125 metres and the other 375 metres long are running in opposite directions on parallel tracks, at the speed of 81 km/hr and 63 km/hr respectively. How much time will they take to cross each other?

• A. 25 sec
• B. 15 sec
• C. 12.5 sec
• D. 22.5 sec

Answer 1

Answer:

C. 12.5 sec

Solution: Given: Length of the first train = 125 metres Length of the second train = 375 metres Speed of the first train = 81 km/hr Speed of the second train = 63 km/hr Formula used: Time is taken to cross each other = Total distance to be covered / Relative speed Solution: Total distance to be covered = Length of first train + Length of second train = 125 metres + 375 metres = 500 metres Relative speed = Speed of first train + Speed of second train = (81 km/hr + 63 km/hr) × (5/18) m/s [Converting km/hr to m/s] = (144 × 5)/18 m/s = 40 m/s Time is taken to cross each other = Total distance to be covered / Relative speed = 500 metres/40 m/s = 12.5 seconds Therefore, the two trains will take 12.5 seconds to cross each other.