Multiple choice

Two trains, each 100 m long, moving in opposite directions, cross each other in 8 seconds. If one is moving twice as fast the other, then the speed of the faster train is

  1. 30 km/hr

  2. 45 km/hr

  3. 60 km/hr

  4. 75 km/hr
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total distance = 100 + 100 = 200 m. Time = 8 s. Relative speed = 200/8 = 25 m/s. Let speeds be v and 2v. 3v = 25 m/s, so v = 25/3 m/s. Faster train = 50/3 m/s. Convert to km/hr: (50/3) * (18/5) = 60 km/hr.

AI explanation

When two trains move in opposite directions, their relative speed is the sum of their speeds, so the distance covered to cross each other is 100 m + 100 m = 200 m in 8 seconds. The relative speed is 200 m / 8 s = 25 m/s, which converts to 25 * 18/5 = 90 km/hr. If the slower speed is v, the faster is 2v, making v + 2v = 90 km/hr, so 3v = 90 and v = 30 km/hr. The faster train's speed is 2 * 30 = 60 km/hr.

Keep practicing — related questions