Multiple choice

In how many seconds will a 300 m long train cross a bike moving at a speed of 40 km/hr in the opposite direction to it, if the speed of the train is 104 km/hr?

  1. 10 seconds

  2. 7.5 seconds

  3. 7 seconds

  4. 6.5 seconds

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Relative speed = 104 + 40 = 144 km/hr = 144 * (5/18) = 40 m/s. Time = distance / relative speed = 300 / 40 = 7.5 seconds.

AI explanation

When two objects move in opposite directions, their relative speed is the sum of their individual speeds. The relative speed is 104 + 40 = 144 km/hr, which converts to 40 m/s by multiplying by 5/18. The total distance the train needs to cover to pass the bike is its own length, 300 m. The required time is 300 divided by 40, which equals 7.5 seconds.

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