Question

Two trains are moving in the same direction at 65 km/hr and 45 km/hr. respectively. The faster train crosses a man in the slower train in 18 seconds. What is the length of the faster train?

• A. 120 m
• B. 130 m
• C. 105 m
• D. 100 m

Answer 1

Answer:

D. 100 m

Solution: Given: Speed of the first train = 65 km/hr Speed of the second train = 45 km/hr The faster train crossed a man who is sitting on the slower train in = 18 seconds Formula: If the speed of the two trains be x km/hr and y km/hr respectively if x > y. Relative speed, if directions are = (x + y) km/hr Relative speed, if same directions = (x - y) km/hr Speed = Distance/Time 1 km/hr = 5/18 m/s Calculation: Relative speed of both trains, if both are running in same direction = (65 - 45) = 20km/hr Let length of faster train be x m, According to the question 20 × (5/18) = x/18 ⇒ x = 20 × (5/18) × 18 ⇒ x = 100 m ∴ Length of the faster train is 100 m.