Wheel Revolutions to Radius — Distance 44 km in 4000 Revolutions (Recovery Applied): A wheel makes 4000 revolutions while moving 44 km. Find the radius of the wheel.

Difficulty: Medium

Correct Answer: 1.75 m

Explanation:


Introduction / Context:
The original options listed very large radii in metres that did not align with the computation, suggesting inconsistency. By the Recovery-First Policy, we keep the given distance and revolutions and reconstruct coherent options around the correct result. The problem uses distance = revolutions * circumference and circumference = 2 * π * r.



Given Data / Assumptions:

  • Total distance D = 44 km = 44000 m
  • Number of revolutions N = 4000
  • Circumference C = D / N
  • C = 2 * π * r


Concept / Approach:
Each revolution covers one circumference. Compute C, then solve for r = C / (2 * π). Keep metres throughout and round sensibly only at the end to match practical answer choices.



Step-by-Step Solution:

C = 44000 / 4000 = 11 m.r = C / (2 * π) = 11 / (2 * π) ≈ 11 / 6.28318 ≈ 1.75 m.Thus, radius ≈ 1.75 m.


Verification / Alternative check:

Check: 2 * π * 1.75 ≈ 10.9956 m; 4000 * 10.9956 ≈ 43982 m ≈ 44 km (rounding error acceptable).


Why Other Options Are Wrong:

  • 1.25 m and 1.50 m yield too small circumferences.
  • 2.00 m and 2.25 m yield distances exceeding 44 km.


Common Pitfalls:

  • Mistaking diameter for radius; using C = π * d means d = 11/π and r = d/2.


Final Answer:
1.75 m.

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