Skip to ContentGo to accessibility pageKeyboard shortcuts menu
Physics

# Problems

PhysicsProblems

## 14.1Speed of Sound, Frequency, and Wavelength

25 .
A bat produces a sound at $17,250\,\text{Hz}$ and wavelength $0.019\,\text{m}$. What is the speed of the sound?
1. $1.7 \times 10^6\,\text{m}/\text{s}$
2. $8.6\times 10^5\,\text{m}/\text{s}$
3. $1.15\times 10^{-6}\,\text{m/s}$
4. $3.28\times 10^2\,\text{m}/\text{s}$
26 .
 Medium vw (m/s) Gases at 0 °C Air 331 Carbon dioxide 259 Oxygen 316 Helium 965 Hydrogen 1290 Liquids at 20 °C Ethanol 1160 Mercury 1450 Water, fresh 1480 Sea water 1540 Human tissue 1540 Solids (longitudinal or bulk) Vulcanized rubber 54 Polyethylene 920 Marble 3810 Glass, Pyrex 5640 Lead 1960 Aluminum 5120 Steel 5960
Table 14.2
A sound wave with a frequency of 80 Hz is traveling through air at 0°C. The sound wave enters a block of aluminum. If the sound's frequency does not change, what happens to the sound's wavelength?
1. It's wavelength increases by a factor of 4.2.
2. It's wavelength increases by a factor of 18.
3. It's wavelength decreases by a factor of 4.2.
4. It's wavelength decreases by a factor of 18.

## 14.2Sound Intensity and Sound Level

27.

Calculate the sound intensity for a sound wave traveling through air at 15° C and having a pressure amplitude of 0.80 Pa. (Hint—Speed of sound in air at 15° C is 340 m/s .)

1. 9.6×10−3 W / m2
2. 7.7×10−3 W / m2
3. 9.6×10−4 W / m2
4. 7.7×10−4 W / m2
28 .
The sound level in dB of a sound traveling through air at $0^{\circ}\text{C}$ is $97\,\text{dB}$. Calculate its pressure amplitude.
1. $4.3\,\text{Pa}$
2. $0.20\,\text{Pa}$
3. $0.04\,\text{Pa}$
4. $2.1\,\text{Pa}$

## 14.3Doppler Effect and Sonic Booms

29 .
An ambulance is moving away from you. You are standing still and you hear its siren at a frequency of 101 Hz. You know that the actual frequency of the siren is 105 Hz. Assuming the speed of sound is 331 m/s, what is the speed of the ambulance?
1. $17.07\,\text{m}/\text{s}$
2. $16.55\,\text{m}/\text{s}$
3. $14.59\,\text{m}/\text{s}$
4. $13.1\,\text{m/s}$
30 .
An ambulance passes you at a speed of 15.0m/s and its siren has a frequency of 995 Hz. Assuming the speed of sound in air is 331m/s, what is difference in the frequencies you perceive before and after it passes you?
1. $47.0\,\text{Hz}$
2. $43.0\,\text{Hz}$
3. $94.9\,\text{Hz}$
4. $90.0\,\text{Hz}$

## 14.4Sound Interference and Resonance

31 .
What is the length of an open-pipe resonator with a fundamental frequency of $400.0\,\text{Hz}$? (Assume the speed of sound is $331\,\text{m/s}$.)
1. $165.1\,\text{cm}$
2. $82.22\,\text{cm}$
3. $20.25\,\text{cm}$
4. $41.38\,\text{cm}$
32 .
An open-pipe resonator has a fundamental frequency of $250\,\text{Hz}$. By how much would its length have to be changed to get a fundamental frequency of $300.0\,\text{Hz}$? (Assume the speed of sound is $331\,\text{m/s}$.)
1. $77.32\,\text{cm}$
2. $44.09\,\text{cm}$
3. $32.16\,\text{cm}$
4. $11.03\,\text{cm}$
Citation/Attribution

This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute Texas Education Agency (TEA). The original material is available at: https://www.texasgateway.org/book/tea-physics . Changes were made to the original material, including updates to art, structure, and other content updates.

Attribution information
• If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
Access for free at https://openstax.org/books/physics/pages/1-introduction
• If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
Access for free at https://openstax.org/books/physics/pages/1-introduction
Citation information

© Jun 7, 2024 Texas Education Agency (TEA). The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.