1. At a compression in a sound wave,
Q16.1
At a compression in a sound wave,
A. particles are displaced by the maximum distance in the same direction as the wave is moving.
B. particles are displaced by the maximum distance in the direction opposite to the direction the wave is moving.
C. particles are displaced by the maximum distance in the direction perpendicular to the direction the wave is moving.
D. the particle displacement is zero.
E. more than one of the above can be true, depending on circumstances.
Answer: D

2. A16.1
At a compression in a sound wave,
A. particles are displaced by the maximum distance in the same direction as the wave is moving.
B. particles are displaced by the maximum distance in the direction opposite to the direction the wave is moving.
C. particles are displaced by the maximum distance in the direction perpendicular to the direction the wave is moving.
D. the particle displacement is zero.
E. more than one of the above can be true, depending on circumstances.

3. A. causes the intensity to increase by a factor of 16.
Q16.2
Increasing the pressure amplitude of a sound wave by a factor of 4 (while leaving the frequency unchanged)
A. causes the intensity to increase by a factor of 16.
B. causes the intensity to increase by a factor of 4.
C. causes the intensity to increase by a factor of 2.
D. has no effect on the wave intensity.
E. changes the intensity by an amount dependent on the frequency.
Answer: A

4. A16.2
Increasing the pressure amplitude of a sound wave by a factor of 4 (while leaving the frequency unchanged)
A. causes the intensity to increase by a factor of 16.
B. causes the intensity to increase by a factor of 4.
C. causes the intensity to increase by a factor of 2.
D. has no effect on the wave intensity.
E. changes the intensity by an amount dependent on the frequency.

5. A. causes the intensity to increase by a factor of 16.
Q16.3
Increasing the frequency of a sound wave by a factor of 4 (while leaving the pressure amplitude unchanged)
A. causes the intensity to increase by a factor of 16.
B. causes the intensity to increase by a factor of 4.
C. causes the intensity to increase by a factor of 2.
D. has no effect on the wave intensity.
E. changes the intensity by an amount dependent on the frequency.
Answer: D

6. A16.3
Increasing the frequency of a sound wave by a factor of 4 (while leaving the pressure amplitude unchanged)
A. causes the intensity to increase by a factor of 16.
B. causes the intensity to increase by a factor of 4.
C. causes the intensity to increase by a factor of 2.
D. has no effect on the wave intensity.
E. changes the intensity by an amount dependent on the frequency.

7. A. The normal-mode wavelengths are unaffected.
Q16.4
The air in an organ pipe is replaced by helium (which has a lower molar mass than air) at the same temperature. How does this affect the normal-mode wavelengths of the pipe?
A. The normal-mode wavelengths are unaffected.
B. The normal-mode wavelengths increase.
C. The normal-mode wavelengths decrease.
D. Some normal-mode wavelengths increase, while others decrease.
E. The answer depends on whether the pipe is open or closed.
Answer: A

8. A16.4
The air in an organ pipe is replaced by helium (which has a lower molar mass than air) at the same temperature. How does this affect the normal-mode wavelengths of the pipe?
A. The normal-mode wavelengths are unaffected.
B. The normal-mode wavelengths increase.
C. The normal-mode wavelengths decrease.
D. Some normal-mode wavelengths increase, while others decrease.
E. The answer depends on whether the pipe is open or closed.

9. A. The normal-mode frequencies are unaffected.
The air in an organ pipe is replaced by helium (which has a lower molar mass than air) at the same temperature. How does this affect the normal-mode frequencies of the pipe?
A. The normal-mode frequencies are unaffected.
B. The normal-mode frequencies increase.
C. The normal-mode frequencies decrease.
D. Some normal-mode frequencies increase, while others decrease.
E. The answer depends on whether the pipe is open or closed.
Answer: B

10. A16.5
The air in an organ pipe is replaced by helium (which has a lower molar mass than air) at the same temperature. How does this affect the normal-mode frequencies of the pipe?
A. The normal-mode frequencies are unaffected.
B. The normal-mode frequencies increase.
C. The normal-mode frequencies decrease.
D. Some normal-mode frequencies increase, while others decrease.
E. The answer depends on whether the pipe is open or closed.

11. Q16.6
When you blow air into an open organ pipe, it produces a sound with a fundamental frequency of 440 Hz. If you close one end of this pipe, the new fundamental frequency of the sound that emerges from the pipe is
A. 110 Hz.
B. 220 Hz.
C. 440 Hz.
D. 880 Hz.
E Hz.
Answer: B

12. A16.6
When you blow air into an open organ pipe, it produces a sound with a fundamental frequency of 440 Hz. If you close one end of this pipe, the new fundamental frequency of the sound that emerges from the pipe is
A. 110 Hz.
B. 220 Hz.
C. 440 Hz.
D. 880 Hz.
E Hz.

13. A. A stopped organ pipe of length L
Q16.7
A stopped organ pipe of length L has a fundamental frequency of 220 Hz. For which of the following organ pipes will there be a resonance if a tuning fork of frequency 660 Hz is sounded next to the pipe?
A. A stopped organ pipe of length L
B. A stopped organ pipe of length 2L
C. An open organ pipe of length L
D. An open organ pipe of length 2L
E. More than one of the above
Answer: E 13

14. A. A stopped organ pipe of length L
A stopped organ pipe of length L has a fundamental frequency of 220 Hz. For which of the following organ pipes will there be a resonance if a tuning fork of frequency 660 Hz is sounded next to the pipe?
A. A stopped organ pipe of length L
B. A stopped organ pipe of length 2L
C. An open organ pipe of length L
D. An open organ pipe of length 2L
E. More than one of the above 14

15. Q16.8
You hear a sound with a frequency of 256 Hz. The amplitude of the sound increases and decreases periodically: It takes 2 seconds for the sound to go from loud to soft and back to loud. This sound can be thought of as a sum of two waves with frequencies
A. 256 Hz and 2 Hz.
B. 254 Hz and 258 Hz.
C. 255 Hz and 257 Hz.
D Hz and Hz.
E Hz and Hz.
Answer: E

16. A16.8
You hear a sound with a frequency of 256 Hz. The amplitude of the sound increases and decreases periodically: It takes 2 seconds for the sound to go from loud to soft and back to loud. This sound can be thought of as a sum of two waves with frequencies
A. 256 Hz and 2 Hz.
B. 254 Hz and 258 Hz.
C. 255 Hz and 257 Hz.
D Hz and Hz.
E Hz and Hz.

17. A. a higher frequency and a shorter wavelength.
On a day when there is no wind, you are moving toward a stationary source of sound waves. Compared to what you would hear if you were not moving, the sound that you hear has
A. a higher frequency and a shorter wavelength.
B. the same frequency and a shorter wavelength.
C. a higher frequency and the same wavelength.
D. the same frequency and the same wavelength.
E. none of the above.
Answer: C

18. A16.9
On a day when there is no wind, you are moving toward a stationary source of sound waves. Compared to what you would hear if you were not moving, the sound that you hear has
A. a higher frequency and a shorter wavelength.
B. the same frequency and a shorter wavelength.
C. a higher frequency and the same wavelength.
D. the same frequency and the same wavelength.
E. none of the above.

19. A. a higher frequency and a shorter wavelength.
On a day when there is no wind, you are at rest and a source of sound waves is moving toward you. Compared to what you would hear if the source were not moving, the sound that you hear has
A. a higher frequency and a shorter wavelength.
B. the same frequency and a shorter wavelength.
C. a higher frequency and the same wavelength.
D. the same frequency and the same wavelength.
E. none of the above.
Answer: A

20. A16.10
On a day when there is no wind, you are at rest and a source of sound waves is moving toward you. Compared to what you would hear if the source were not moving, the sound that you hear has
A. a higher frequency and a shorter wavelength.
B. the same frequency and a shorter wavelength.
C. a higher frequency and the same wavelength.
D. the same frequency and the same wavelength.
E. none of the above.

21. A. Intensity = 2.0 10–5 W/m2, frequency = 100 Hz
Q-RT16.1
Four sinusoidal sound waves propagate in the same region of our atmosphere. Rank the waves in order of their displacement amplitude, from largest to smallest.
A. Intensity = –5 W/m2, frequency = 100 Hz
B. Intensity = –5 W/m2, frequency = 200 Hz
C. Intensity = –5 W/m2, frequency = 200 Hz
D. Intensity = –5 W/m2, frequency = 800 Hz
Answer: ACBD 21

22. A. Intensity = 2.0 10–5 W/m2, frequency = 100 Hz
A-RT16.1
Four sinusoidal sound waves propagate in the same region of our atmosphere. Rank the waves in order of their displacement amplitude, from largest to smallest.
A. Intensity = –5 W/m2, frequency = 100 Hz
B. Intensity = –5 W/m2, frequency = 200 Hz
C. Intensity = –5 W/m2, frequency = 200 Hz
D. Intensity = –5 W/m2, frequency = 800 Hz
Answer: ACBD 22