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Which of the following describes a condition in which an individual would not hear an echo?

A. An individual is standing 30 meters in front of the reflecting surface.

B. An individual is standing in the range of the sound waves coming from the original sound source as well as the reflected waves.

C. A sound wave reaches the ear and the reflected wave reaches the ear less than 0.1 second later.

D. The reflecting source is approximately 21.5 meters from the individual.

Answer: C. A sound wave reaches the ear and the reflected wave reaches the ear less than 0.1 second later.

Echoes are reflected sound waves, and they can be heard from a distance, provided that distance is not less than 17 meters, which disqualifies options A and D. If an individual is standing in the range of the sound waves coming from both the original source and the reflected waves, then they will definitely hear an echo. If however, sound waves reach the ear less than 0.1 seconds after the sound is made, then the ear will interpret it as a part of the original sound, and they will not hear an echo.

Physics

3 years ago

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