Multiple choice

Two trains of lengths $100\ m$ and $150\ m$ are travelling in opposite directions at speeds of $75\ kmph$ and $50\ kmph$ respectively. What is the time taken by them to cross each other?

  1. $7.4 s$
  2. $7.2 s$
  3. $7s$
  4. $6.8 s$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Relative speed = 75 + 50 = 125 kmph. Convert to m/s: 125 * (5/18) = 625/18 m/s. Total distance = 100 + 150 = 250 m. Time = Distance / Speed = 250 / (625/18) = 250 * 18 / 625 = 7.2 seconds.

AI explanation

When two trains travel in opposite directions, their relative speed is the sum of their individual speeds. The combined speed is 75 kmph plus 50 kmph, equaling 125 kmph, which converts to 125 multiplied by 5/18, or 625/18 m/sec. The total distance they must cover to cross each other is 100 m plus 150 m, equaling 250 m. The time taken is distance divided by relative speed, so 250 divided by 625/18 equals 7.2 seconds.

Keep practicing — related questions