Multiple choice

A $120\ m$ long train is moving in a direction with speed $20m/s$. A train $B$ moving with $30m/s$ in the opposite direction and $130\ m$ long crosses the first train in a time of :

  1. $5s$
  2. $36s$
  3. $38s$
  4. $None\ of\ these$
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A Correct answer
Explanation

Relative speed = 20 + 30 = 50 m/s. Total distance to cover = 120 + 130 = 250 m. Time = distance / speed = 250 / 50 = 5 seconds.

AI explanation

When two trains travel in opposite directions, their relative speed is the sum of their individual speeds: 20 m/s plus 30 m/s equals 50 m/s. The total distance they must cover to cross each other is the sum of their lengths, 120 m plus 130 m, which equals 250 m. Dividing the total distance by the relative speed (250 m divided by 50 m/s) results in 5 s.

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