Multiple choice

Two trains are each $50\ m$ long moving parallel towards each other at speeds $10\ { m }/{ s }$ and $15\ { m }/{ s }$ respectively. After what time will they pass each other?

  1. $5\sqrt { \dfrac { 2 }{ 3 } } \ sec$
  2. $4\ sec$
  3. $2\ sec$
  4. $6\ sec$
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B Correct answer
Explanation

Relative speed = 10 + 15 = 25 m/s. Total distance to cover = 50 + 50 = 100 m. Time = Distance / Speed = 100 / 25 = 4 seconds.

AI explanation

Because the two trains are moving in opposite directions, their relative speed is calculated by adding their speeds, resulting in 10 m/s + 15 m/s = 25 m/s. The total distance they need to cover to pass each other is the sum of their lengths, giving 50 m + 50 m = 100 m. Using the formula time equals distance divided by relative speed, the time taken is 100 m divided by 25 m/s, which is 4 sec.

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