A person should stand approximately 28 feet from a reflecting plane to hear their echo distinctly. This distance allows for a sufficient time delay between the emission of sound and the return of its reflection, making the echo perceptible to the listener. Shorter distances may not provide enough time for the sound waves to reflect back, while longer distances can diminish the intensity of the echo.
Share
To hear their echo distinctly, a person should stand approximately [C] 28 feet from a reflecting plane. This distance is crucial because it allows enough time for sound waves emitted by the person to travel to the reflecting surface and back, creating a perceptible delay between the original sound and its reflected echo.
The specific distance of 28 feet is based on the speed of sound in air (~343 meters per second or ~1125 feet per second at room temperature). Therefore, sound travels approximately 28 feet in 1/10 of a second, which is the minimum time interval typically required for a clear echo to be perceived by the human ear.
Understanding the distance for hearing echoes helps in practical applications such as acoustic design, outdoor activities, and safety in environments where sound reflection may affect communication and perception. Thus, the correct answer for hearing an echo is [C] 28 feet.