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A metro train begins from rest and reaches a speed of 108 km/h in 5 s. It then continues at this constant speed and finally is brought to rest by a uniform retardation over a distance of 45 m. If the entire journey covers 395 m, what is the total time taken?

1. 12.2 s
2. 15.3 s
3. 9 s
4. 17.2 s

Correct answer: 17.2 s

Solution

The total time taken includes the time to accelerate to 108 km/h, the time spent at constant speed, and the time to decelerate over 45 m. Calculating each segment shows that the total time sums up to 17.2 seconds, confirming the correct option.

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