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प्रश्न
Calculate the minimum distance in air required between the source of sound and the obstacle to hear an echo. Take speed of sound in air = 350 m s-1
उत्तर
Velocity = `(2D)/"Time"`
350 = `(2 × D)/ 0.1`
D = `(350 × 0.1) / 2`
D = 17.5 m
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