A train with a length of 335 m is travelling at a speed of 90 km/h. Wh

A train with a length of 335 m is travelling at a speed of 90 km/h. What is the time taken by the train to pass a 290 m long platform?

25 s
23 s
20 s
30 s
This question was previously asked in
UPSC CISF-AC-EXE – 2024
The correct answer is 25 seconds.
To pass a platform, a train must cover a distance equal to its own length plus the length of the platform.
Total distance to be covered = Length of train + Length of platform.
Total distance = 335 m + 290 m = 625 m.
The speed of the train is given in km/h, so we need to convert it to m/s to be consistent with the distance unit (meters) and time unit (seconds).
Speed = 90 km/h.
To convert km/h to m/s, multiply by the factor (1000 m / 3600 s) = 5/18.
Speed in m/s = 90 * (5/18) m/s = (90/18) * 5 m/s = 5 * 5 m/s = 25 m/s.
The time taken is calculated using the formula: Time = Distance / Speed.
Time = 625 m / 25 m/s.
Time = 25 seconds.
When a train crosses a stationary object with negligible length (like a pole or a man), the distance covered is just the length of the train. When it crosses an object with considerable length (like a bridge or a platform), the distance is the sum of the train’s length and the object’s length. The conversion factor 5/18 comes from $1 \text{ km} = 1000 \text{ m}$ and $1 \text{ hour} = 3600 \text{ seconds}$, so $1 \text{ km/h} = \frac{1000}{3600} \text{ m/s} = \frac{5}{18} \text{ m/s}$.
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