Two trains of length 145 meters and 175 meters are running on parallel tracks.…
2025
Two trains of length 145 meters and 175 meters are running on parallel tracks. When they run in the same direction the faster train crosses the slower train in 80 seconds and when they run in opposite direction they cross each other in 20 seconds. What is the speed of each train?
- A.
13 m/sec, 5 m/sec
- B.
14 m/sec, 8 m/sec
- C.
10 m/sec, 6 m/sec
- D.
18 m/sec, 9 m/sec
Attempted by 8 students.
Show answer & explanation
Correct answer: C
Let the speeds of the two trains be v1 and v2 meters per second, where v1 is the faster train.
Total distance to cross = 145 + 175 = 320 m
When trains move in the same direction, relative speed = v1 - v2. Given crossing time = 80 s, so v1 - v2 = 320 / 80 = 4 m/sec
When trains move in opposite directions, relative speed = v1 + v2. Given crossing time = 20 s, so v1 + v2 = 320 / 20 = 16 m/sec
Solve the system: v1 - v2 = 4 and v1 + v2 = 16. Adding gives 2v1 = 20, so v1 = 10 m/sec. Then v2 = 16 - v1 = 6 m/sec
Answer: the faster train has speed 10 m/sec and the slower train has speed 6 m/sec.