Problem data: V (linear speed of a bicycle wheel) = 72 km / h (in SI V = 20 m / s); D (wheel diameter) = 90 cm (SI D = 0.9 m).
We express the frequency with which a given bicycle wheel rotates from the formula: V = Π * D * ν, whence ν = V / (Π * D).
Let’s calculate: ν = 20 / (3 * 0.9) ≈ 7.4 Hz.
Answer: The bicycle wheel will rotate at 7.4 Hz.
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