Chapter 5: Problem 40

What is an echo?

Short Answer

Expert verified

Provide an example of an echo with a calculation of the time delay. Answer: An echo is a reflection of sound off a solid surface that reaches the listener after a delay. The delay is determined by the distance between the sound source and the reflecting surface, as well as the speed of sound in the medium. In the example of a person clapping their hands 50 meters away from a wall and assuming the speed of sound in air is 340 meters per second, the time delay for the echo can be calculated as (2 x 50)/340 ≈ 0.29 seconds. The person would hear the echo approximately 0.29 seconds after the direct sound.

Step by step solution

Understanding sound and its properties

Sound is a vibration that travels through a medium, like air or water. It is a type of mechanical wave, which means that it moves through the medium by displacing the particles in the medium. The speed at which sound travels through a medium depends on the properties of that medium.

Defining an echo

An echo is a sound that is reflected off a solid surface and reaches the listener after a delay. When a sound wave encounters a surface, some of the sound energy is reflected back towards the source, while the rest is absorbed by the surface or transmitted through it. The reflected sound wave that travels back to the listener is called an echo.

Understanding the delay in an echo

The delay between the direct sound and its echo depends on the distance between the sound source and the reflecting surface, as well as the speed of sound in the medium. The total distance traveled by the sound wave before reaching the listener as an echo is twice the distance between the sound source and the reflecting surface (assuming the listener is at the sound source). The time it takes for the sound wave to travel this distance can be found using the formula: Time = \frac{2 \times distance}{speed \, of \, sound}

Example of an echo

Imagine someone standing in front of a large wall, 50 meters away from it, and clapping their hands. The sound of the clap travels through the air, hits the wall, and then reflects back to the person. If we assume the speed of sound in air is approximately 340 meters per second, we can use the formula from Step 3 to calculate the time delay for the echo: Time = \frac{2 \times 50}{340} = \frac{100}{340} \approx 0.29 \, seconds So, the person would hear the echo of their clap approximately 0.29 seconds after hearing the direct sound.

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What is an echo?

Short Answer

Step by step solution

Understanding sound and its properties

Defining an echo

Understanding the delay in an echo

Example of an echo

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