Multiple choice

Two trains are moving at 50 kmph and 70 kmph in opposite directions. Their lengths are 150 m and 100 m respectively. The time they will take to pass each other completely is?

  1. 3 sec

  2. 7 ½ sec

  3. 4 ½ sec

  4. 5 sec
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Relative speed = 50 + 70 = 120 kmph = 120 * (5/18) m/s = 100/3 m/s. Total distance = 150 + 100 = 250 m. Time = Distance / Speed = 250 / (100/3) = 750 / 100 = 7.5 seconds.

AI explanation

When two trains travel in opposite directions, use the relative speed formula by adding their speeds to get 50 kmph plus 70 kmph equals 120 kmph, which converts to 120 multiplied by 5/18, equaling 100/3 m/s. The total distance to cover is the sum of their lengths at 250 m. Divide 250 by 100/3 to get 7.5 seconds. The time they will take to pass each other completely is 7 1/2 sec.

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