Using v ≈ 340 m/s in air, the minimum distance to a reflecting wall for a clear echo (sound goes and returns in 0.1 s) is about:
A1.7 m
B340 m
C34 m
D17 m
Answer & Solution
Correct answer: D. 17 m
Total path = 340 × 0.1 = 34 m; one-way distance ≈ 17 m.
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