A train 175 m long is running at a speed of 45 km/Hr. Time taken by the train to cross a pole is ...

ESIC Nursing Officer 2016 (Shift -2)

Non Nursing Subjects

Medium

Appeared in: ESIC Nursing Officer 2016 (Shift -2)

Explanation

To cross a stationary pole, the train must travel a distance equal to its own length, which is 175 meters.
The train's speed of 45 km/hr must be converted to meters per second (m/s) by multiplying by the standard factor of 5/18, which results in 12.5 m/s.
Using the fundamental formula Time = Distance / Speed, the calculation is 175 m divided by 12.5 m/s, which equals 14 seconds.

Option A: This is an incorrect calculation. A time of 15 seconds would imply a speed of approximately 11.67 m/s (or 42 km/hr), not the given 12.5 m/s.
Option B: This is an incorrect calculation. A time of 16 seconds would imply a speed of approximately 10.94 m/s.
Option C: This is an incorrect calculation. This value might be obtained if the km/hr to m/s conversion was done incorrectly, for instance, by multiplying by 18/5 instead of 5/18.

Visual 1: Infographic: A diagram showing a train of length 'L' starting to cross a pole and then completely passing it. The total distance covered is clearly marked as 'L'.
Visual 2: Flowchart: A step-by-step process for solving 'train crossing a pole' problems: 1. Identify Length & Speed -> 2. Check Units -> 3. Convert Speed to m/s (if needed) -> 4. Apply Formula: Time = Length / Speed -> 5. Calculate Result.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculating time, speed, and distance in the context of a moving object crossing a stationary point as background academic context rather than a clinical decision trigger.
This type of question tests fundamental quantitative aptitude, a key skill for competitive exams that require logical reasoning and numerical ability.
Mastering unit conversion (e.g., km/hr to m/s) is a critical and transferable skill for accuracy in various science and mathematics problems.
What if the train was crossing a 225m long platform? In that case, the total distance to cover would be the sum of the train's length and the platform's length (175m + 225m = 400m). The time taken would then be 400m / 12.5 m/s = 32 seconds.

How to Approach the Question

First, identify the core task: find the time for a train to cross a stationary point (a pole).
Recognize that for crossing a pole, the distance the train must cover is its own length (175 m).
Observe the units provided. The length is in meters, but the speed is in km/hr. This mismatch signals that a unit conversion is necessary.
Convert the speed from km/hr to m/s by multiplying by the standard conversion factor of 5/18.
Apply the fundamental physics formula: Time = Distance / Speed.
Perform the final division to calculate the time in seconds.

Concept Tested & Keywords

Concept Tested: Calculating time, speed, and distance in the context of a moving object crossing a stationary point.
Stem keywords: train, 175 m long, speed, 45 km/Hr, cross a pole
Lead-in keywords: Time taken
Negative lead-in flag: false

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