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