A 270 meter long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. What is the length of the other train?

Given Data

• Train A length = 270 m; speed = 120 km/hr
• Train B length = ?; speed = 80 km/hr
• Opposite directions; time to cross each other = 9 s

Step 1: Relative speedv_rel = 120 + 80 = 200 km/hr = 200 × (5/18) = 55.5556 m/s

Step 2: Use distance = speed × timeDistance covered in crossing = (lengths sum) = 270 + L270 + L = 55.5556 × 9 = 500L = 500 − 270 = 230 m

Checks & Common Pitfalls

• Use the sum of speeds for opposite directions.
• Crossing distance is the sum of lengths.

Final AnswerThe length of the other train is 230 m.