Two trains are running in opposite directions with the same speed. If the length of each train is 120 metres and they cross each other in 12 seconds, then the speed of each train (in km/hr) is:

Given Data

• Two trains run in opposite directions with the same speed
• Each train length = 120 m
• They cross each other in 12 s
• Required: speed of each train (km/hr)

Step 1: Use relative speedLet each speed = v m/s ⇒ relative speed = 2v m/sDistance to cross = 120 + 120 = 240 m12 = 240 ÷ (2v) ⇒ 2v = 20 ⇒ v = 10 m/s

Step 2: Convert to km/hr10 × (18/5) = 36 km/hr

Checks & Common Pitfalls

• Opposite directions ⇒ sum of speeds.
• Add the two lengths for complete crossing.

Final AnswerEach train's speed is 36 km/hr.