A train 108 m long moving at a speed of 50 km/hr crosses a train 112 m long coming from opposite direction in 6 seconds. The speed of the second train is:

Given Data

• Train A length = 108 m; speed = 50 km/hr
• Train B length = 112 m; speed = ? km/hr
• They come from opposite directions
• Time to completely cross = 6 s

Step 1: Relative speed and crossing distanceOpposite directions ⇒ v_rel = 50 + x (km/hr)Total distance to cross = 108 + 112 = 220 m

Step 2: Form the equation using time = distance ÷ speed6 = 220 ÷ ( 50 + 𝑥 ) × ( 5 / 18 ) (50+x)×(5/18)⇒ 6 = 220 × 18 ÷ 5 ( 50 + 𝑥 ) 5(50+x) = 3960 ÷ 5 ( 50 + 𝑥 ) 5(50+x)⇒ 30(50 + x) = 3960 ⇒ 50 + x = 132 ⇒ x = 82 km/hr

Checks & Common Pitfalls

• Use the sum of speeds for opposite directions.
• Crossing distance is the sum of lengths.
• Maintain units carefully when converting km/hr to m/s.

Final AnswerThe second train's speed is 82 km/hr.