Problems on Trains – Time to pass a fixed point (single length used): A 110 m long train runs at 36 km/h. How long will it take to pass a fixed point (e.g., a signal post)?

Difficulty: Easy

Correct Answer: 11 sec.

Explanation:


Introduction / Context:
To pass a fixed point, the train covers its own length at its running speed. Convert speed to m/s and divide train length by that speed to obtain time.


Given Data / Assumptions:

  • L_train = 110 m.
  • Speed = 36 km/h = 10 m/s.


Concept / Approach:
Time = distance / speed = L_train / v.


Step-by-Step Solution:
v = 36 * (1000/3600) = 10 m/s.t = 110 / 10 = 11 s.


Verification / Alternative check:
At 10 m/s, in 11 s the train covers 110 m, exactly its length, thus fully clearing the point.


Why Other Options Are Wrong:
12, 13, 15, 9 s are not equal to 110/10.


Common Pitfalls:
Adding platform/tunnel length when none exists; mis-converting km/h to m/s.


Final Answer:
11 sec.

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