An engine wheel has circumference 300 cm (3 m) and makes 10 revolutions in 6 seconds. What is the linear speed of the wheel in km/h?
Aptitude
Time and Distance
Difficulty: Easy
Choose an option
Answer
Correct Answer: 18
Explanation
Introduction / Context:Linear speed = (revolutions per time) * circumference. Convert the resulting m/s to km/h by multiplying by 3.6.
Given Data / Assumptions:
- Circumference = 300 cm = 3 m.
- 10 revolutions in 6 s.
Concept / Approach:Distance traveled in 6 s = 10 * 3 = 30 m. So speed = 30/6 = 5 m/s. Convert to km/h: 5 * 3.6 = 18 km/h.
Step-by-Step Solution:
Distance per 6 s = 10 * 3 m = 30 m.Speed = 30 / 6 = 5 m/s.5 m/s = 18 km/h.Verification / Alternative check:Using unit factors: (5 m/s)*(18/5) = 18 km/h.
Why Other Options Are Wrong:20/27/36 km/h require different revolution counts or circumference.
Common Pitfalls:Forgetting to convert cm to m or m/s to km/h.
Final Answer:18