Multiple choice

How much time does a train $50$ m long moving at $68$ km/hr take to pass another train $75$ m long moving at $50$ km/hr in the same direction?

  1. $5$ seconds
  2. $10$ seconds
  3. $20$ seconds
  4. $25$ seconds
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D Correct answer
Explanation

Relative speed = 68 - 50 = 18 kmph = 18 * (5/18) = 5 m/s. Total distance = 50 + 75 = 125 m. Time = 125 / 5 = 25 seconds.

AI explanation

Since the trains move in the same direction, their relative speed is the difference between their speeds, which is 68 minus 50, giving 18 km/hr. Converting this to meters per second requires multiplying by 5/18, resulting in a relative speed of 5 m/s. The total distance to be covered is the sum of both trains' lengths, which is 50 plus 75, totaling 125 meters. The time taken is distance divided by relative speed, so 125 divided by 5 gives 25 seconds.

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