Difficulty: Easy
Correct Answer: 10 m
Explanation:
Introduction / Context:
This problem checks your understanding of basic unit conversion between kilometres per hour and metres per second. It is a standard type of speed conversion question that appears in many aptitude and entrance exams. Being comfortable with these conversions saves time and reduces errors in many time and distance problems. Here we are asked to find the distance travelled in a single second by a bus that moves at a known speed in km/h.
Given Data / Assumptions:
Concept / Approach:
To find the distance covered in one second, we convert the given speed from kilometres per hour into metres per second. The standard factor is 5/18 or 18/5 depending on the direction of conversion. Once we know the speed in metres per second, the distance travelled in one second is simply equal to that speed, because distance = speed * time and time is one second.
Step-by-Step Solution:
Verification / Alternative check:
We can also convert directly using the definition. In one hour at 36 km/h, the bus covers 36 km which is 36 000 metres. One hour has 3600 seconds. So distance per second is 36 000 / 3600 = 10 metres. This matches the previous calculation and confirms that the answer is correct.
Why Other Options Are Wrong:
Option 15 m corresponds to a higher speed of 54 km/h, not 36 km/h. Option 12.5 m would correspond to 45 km/h. Option 13.5 m corresponds to approximately 48.6 km/h. None of these match the given speed of 36 km/h when converted back to km/h, so they are not correct for this specific problem.
Common Pitfalls:
Candidates often confuse the conversion factor and multiply by 18/5 instead of 5/18 when moving from km/h to m/s. Another common mistake is to forget that 1 km equals 1000 m or that 1 hour equals 3600 seconds. Some learners also mistakenly think that 36 km/h is 36 m/s, which is not true. Always write the conversion clearly to avoid such errors.
Final Answer:
The bus covers a distance of 10 metres in one second.
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