1. College Physics Chapter 12 Alan Giambattista Betty Richardson
Robert Richardson
4th edition
Chapter 12
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. Question 1
You hear an ambulance with a certain loudness when you are about 100 yards away. Another person hears the same ambulance with an intensity that is about 10 times softer. Roughly, how far is the other person from the ambulance?
A) about the same distance
B) about 300 yards
C) about 1000 yards
D) about 3000 yards
E) about yards

3. Question 2
A CD playing softly has a sound intensity level of about 40 dB. Light street traffic has a level of about 70 dB. How much greater is the intensity of the street traffic compared to the background music?
A) about the same
B) about 10 times
C) about 100 times
D) about 1,000 times
E) about 10,000 times

4. Question 3
You are playing your stereo at a sound level of 90 dB. Your roommate turns on her stereo
at a sound level of 90 dB. The new sound level is
A) 87 dB
B) 90 dB
C) 93 dB
D) 180 dB

5. Question 4
Two stereos are each playing at a sound level of 90 dB. How many more stereos must be turned on to increase the sound level to 96 dB?
A) 1
B) 2
C) 3
D) 4

6. Question 5
You have an empty 2-liter soda bottle and an empty 12-oz soda bottle. Which one has the
higher frequency when you blow across the top?
A) the 2-liter bottle
B) the 12-oz bottle
C) both have the same frequency
D) depends on how hard you blow

7. Question 6
Which of the following diagrams of standing waves in pipes is not an allowed wavelength? C. D. A. B.

8. Question 7
A piano tuner hears 3 beats when she compares the A-string on a piano to A on her pitch pipe, which has a frequency of 440 Hz. She tightens the string and now hears a beat frequency of 1 Hz. The original frequency of the string was
A) 437 Hz
B) 439 Hz
C) 441 Hz
D) 443 Hz

9. Question 8
As you are standing on the lakeshore on a calm day, a friend in a boat 300 m offshore calls out to you. Simultaneously, a friend who is 300 m inland yells to get your attention. Which one will you hear first?
A) the friend offshore
B) the friend inland
C) you will hear both at the same time
D) sound can't carry that far

10. Question 9
Motorcycle Mike is traveling behind an ambulance with a speed of 40 mph. The ambulance, traveling in the same direction, has a speed of 50 mph. When Mike hears the ambulance's siren, the frequency is _______ the actual frequency.
A) higher than
B) the same as
C) lower than

11. Question 10
Motorcycle Mike, traveling at 30 m/s, roars past you as you are standing on the sidewalk.
The frequency of the sound of his engine is 128 Hz. What is the frequency change you
hear as he roars past?
A) increase of 22 Hz
B) decrease of 22 Hz
C) increase of 21 Hz
D) decrease of 24 Hz

12. Question 11
You turn on your TV at 85 dB and your roommate starts vacuuming, which has a sound level of 93 dB. What is the total sound level?
A) 79 dB
B) 94 dB
C) 96 dB
D) 169 dB

13. Question 12
The runners in the 100-m dash can't start running until they hear the sound of the starter's gun. All other things being equal, under what conditions will the runners get a faster start, when the temperature is 100°F or when the temperature is 60° F?
A) on the hot day
B) on the cool day
C) the temperature makes no difference

14. Question 13
Elaine plays concert A on her flute while Eduardo plays concert A on a violin. The speed of the sound waves created by Elaine is __________ the speed of the sound waves created by Eduardo.
A) faster
B) slower
C) the same as
D) can't tell without more information

15. Question 14
A violin string, fixed at each end, has a length of 65 cm. Which pipe will support standing waves with the same wavelengths as the violin string?
A) an open pipe of length 65 cm
B) a closed pipe of length 65 cm
C) an open pipe of length 130 cm
D) a closed pipe of length 130 cm
E) none of the above

16. Question 15
A violin string, fixed at each end, has a length of 65 cm. Which pipe will support standing waves with the same frequencies as the violin string?
A) an open pipe of length 65 cm
B) a closed pipe of length 65 cm
C) an open pipe of length 130 cm
D) a closed pipe of length 130 cm
E) none of the above

17. Question 16
A certain sound causes the tympanic membrane in your ear to vibrate with an amplitude A. A second sound causes the membrane to vibrate with an amplitude 2A. Compare the intensity of the first sound to that of the second.
A) I1 = I2
B) 2I1 = I2
C) 4I1 = I2
D) 6I1 = I2

18. Question 17
A certain sound causes the tympanic membrane in your ear to vibrate with an amplitude A. A second sound causes the membrane to vibrate with an amplitude 2A. Compare the sound intensity level of the first sound to that of the second.
A) b2 = b1
B) b2 = 2b1
C) b2 = 4b1
D) b2 = b1 + 6

19. Question 18 What is the minimum intensity a sound can have? A) 10 W/m2
B) 1 W/m2
C) W/m2
D) none of the above

20. Question 19
An open pipe has a length of 50 centimeters. What is the wavelength of the second
harmonic frequency?
A) 25 cm
B) 50 cm
C) 75 cm
D) 100 cm

21. Question 20
A bat detects the location of a moth by using echo location. If the moth is flying away from the bat, the frequency of the reflected sound the bat hears
A) is higher.
B) is lower.
C) is the same.

22. Answer Key – Chapter 12 B D C A B A C E D