Difficulty: Easy
Correct Answer: 100 m
Explanation:
Introduction / Context:
This problem combines a unit conversion (km/h to m/s) with a time-based distance calculation. It reinforces correct use of the 5/18 factor and proportional reasoning over seconds.
Given Data / Assumptions:
Concept / Approach:
Convert speed to m/s: v(m/s) = v(km/h) * 5/18. Then distance = speed * time in consistent units.
Step-by-Step Solution:
Convert speed: 72 * (5/18) = 4 * 5 = 20 m/s.Distance in 5 s = 20 * 5 = 100 m.
Verification / Alternative check:
Back-convert: 100 m in 5 s implies 20 m/s = 72 km/h, confirming consistency.
Why Other Options Are Wrong:
50 m corresponds to 10 m/s (36 km/h); 60 m corresponds to 12 m/s (43.2 km/h); 74.5 m is a non-integer artifact not supported by exact conversion.
Common Pitfalls:
Using 18/5 instead of 5/18 when converting from km/h to m/s; mixing seconds with hours without converting.
Final Answer:
100 m
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