A train runs at 18 km/h and its length is 120 m. How many seconds will it take to cross a man standing on a platform?

Difficulty: Easy

Correct Answer: 24 s

Explanation:


Introduction / Context:
Passing a stationary man requires the train to cover its own length. Convert speed to m/s and divide train length by that speed to get the time.


Given Data / Assumptions:

  • L = 120 m.
  • v = 18 km/h.


Concept / Approach:
v_mps = 18 * 5/18 = 5 m/s. t = L / v_mps = 120 / 5 seconds.


Step-by-Step Solution:

v_mps = 5 m/s.t = 120 / 5 = 24 s.


Verification / Alternative check:
Back conversion: 24 s at 5 m/s covers 120 m—the train length.


Why Other Options Are Wrong:
12, 22, 36, 44 s misapply conversions or lengths.


Common Pitfalls:
Adding platform length (not needed); forgetting to convert km/h to m/s.


Final Answer:
24 s

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