Deck 12: Sound

Question 1

Compared to the speed of a 400 Hz sound, the speed of a 200 Hz sound through air is

A) twice as great.
B) the same.
C) one half as great.
D) none of these answers are correct

Answer 1

the same.

Question 2

A sound wave in brass has a displacement amplitude of 3.00 mm. The frequency of the sound wave 750 Hz and the speed is 2,813 m/s. If the density of brass is 8.47 × 10³ kg/m³, then what is the pressure amplitude of the sound wave?

A) 5.38 × 10⁸ N/m²
B) 5.10 × 10⁸ N/m²
C) 4.70 × 10⁸ N/m²
D) 4.17 × 10⁸ N/m²
E) 3.37 × 10⁸ N/m²

Answer 2

3.37 × 10⁸ N/m²

Question 3

The Young's modulus of aluminum is 6.90 × 10¹⁰ N/m². If the density of aluminum is 2,700 kg/m³, then what is the speed of longitudinal waves along a thin aluminum rod?

A) 6,360 m/s
B) 6,020 m/s
C) 5,750 m/s
D) 5,060 m/s
E) 4,850 m/s

Answer 3

5,060 m/s

Question 4

The speed of sound in helium is 965 m/s. If the density of helium is 0.179 kg/m³, then what is the bulk modulus of helium?

A) 2.70 × 10⁵ N/m²
B) 2.40 × 10⁵ N/m²
C) 2.20 × 10⁵ N/m²
D) 1.67 × 10⁵ N/m²
E) 1.56 × 10⁵ N/m²

Question 5

The bulk modulus of water is 0.210 × 10¹⁰ N/m² and the density is 1000 kg/m³. The speed of sound in water is

A) 1,450 m/s.
B) 2,150 m/s.
C) 2,490 m/s.
D) 2,750 m/s.
E) 3,100 m/s.

Question 6

You see lightning flash followed 8.2 seconds later by the sound of thunder. The ambient air temperature is 12^°C. The speed of sound in air at 20^°C is 343 m/s. Approximately how far are you from the lightning?

A) 2.77 km
B) 2.74 km
C) 2.18 km
D) 1.69 km

Question 7

The speed of sound in air at 0°C is 331 m/s. What is the speed of sound in air at a temperature of −30°C?

A) 308 m/s
B) 310 m/s
C) 312 m/s
D) 314 m/s
E) 316 m/s

Question 8

The speed of sound is usually greatest in a

A) solid
B) liquid
C) gas
D) vacuum

Question 9

Consider a sound wave traveling from left to right in a certain region in air. If, at a particular time and location, the gauge pressure due to the sound wave is a maximum, what can be said about the displacement of the air molecules at that same time and place?

A) it is zero
B) it is maximum to the right
C) it is maximum to the left
D) Cannot be determined

Question 10

A sound wave radiates from a source uniformly in all directions. If the power of the sound source is 200 watts, then the intensity level of the sound wave 1000 m from the source is

A) 62.8 dB.
B) 66.0 dB.
C) 68.5 dB.
D) 70.5 dB.
E) 72.0 dB.

Question 11

A sound wave radiates from a source uniformly in all directions. If the power of the sound source is 200 watts, then the intensity level of the sound wave 100 m from the source is

A) 98.5 dB.
B) 92.0 dB.
C) 91.5 dB.
D) 89.6 dB.
E) 88.3 dB.

Question 12

The bulk modulus of mercury is 2.85 × 10¹⁰ N/m². If the density of mercury is 1.36 × 10⁴ kg/m³, then what is the speed of sound in mercury?

A) 2.44 × 10⁸ m/s
B) 2.10 × 10⁶ m/s
C) 1.45 × 10³ m/s
D) 6.91 × 10⁻⁴ m/s
E) 4.77 × 10⁻⁷ m/s

Question 13

The speed of longitudinal waves in a long brass rod is 3,260 m/s. If the density of brass is 8,470 kg/m³, then what is the elastic modulus of brass?

A) 9.80 × 10¹⁰ N/m²
B) 9.00 × 10¹⁰ N/m²
C) 8.70 × 10¹⁰ N/m²
D) 8.50 × 10¹⁰ N/m²
E) 8.10 × 10¹⁰ N/m²

Question 14

Sound traveling in air at 23^°C enters a cold front where the air temperature is 2^°C. If the frequency of the sound is 1500 Hz, what is the difference in the wavelength between the cold air and the warm air? The speed of sound in air at 20^°C is 343 m/s.

A) 8.3 mm
B) 9.0 mm
C) 1.9 cm
D) 6.7 cm

Question 15

A sound wave in air has an intensity of 1.00 × 10⁻³ W/m². The density of air is 1.29 kg/m³ and the speed of sound in air is 331 m/s. The pressure amplitude of the sound wave is

A) 0.740 N/m².
B) 0.821 N/m².
C) 0.850 N/m².
D) 0.924 N/m².
E) 0.980 N/m².

Question 16

A sound wave in water has an intensity of 1.00 × 10⁻³ W/m². The density of water is 1,000 kg/m³ and the speed of sound in water is 1,482 m/s. The pressure amplitude of the sound wave is

A) 60.2 N/m².
B) 54.4 N/m².
C) 49.5 N/m².
D) 42.5 N/m².
E) 39.5 N/m².

Question 17

The intensity of a sound wave is directly proportional to

A) the frequency.
B) the amplitude.
C) the square of the amplitude.
D) the square of the speed of sound.
E) none of these answers are correct

Question 18

The speed of sound in air at 0°C is 331 m/s. If the density of air is 1.29 kg/m³, then what is the bulk modulus of air?

A) 1.15 × 10⁵ N/m²
B) 1.41 × 10⁵ N/m²
C) 1.68 × 10⁵ N/m²
D) 2.03 × 10⁵ N/m²
E) 2.50 × 10⁵ N/m²

Question 19

A sound wave in helium has an intensity of 1.00 × 10⁻³ W/m². The density of helium is 0.179 kg/m³ and the speed of sound in helium is 965 m/s. The pressure amplitude of the sound wave is

A) 0.682 N/m².
B) 0.588 N/m².
C) 0.476 N/m².
D) 0.345 N/m².
E) 0.276 N/m².

Question 20

The speed of sound in air at 0°C is 331 m/s. What is the speed of sound in air at a temperature of 30°C?

A) 336 m/s
B) 338 m/s
C) 340 m/s
D) 342 m/s
E) 349 m/s

Question 21

A 30.0 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the frequency of the second mode of vibration?

A) 900 Hz
B) 828 Hz
C) 750 Hz
D) 721 Hz
E) 650 Hz

Question 22

The sound of a bird singing is given as 5 dB. What is the intensity of the sound of a bird singing?

A) 1.95 × 10⁻¹² W/m²
B) 2.04 × 10⁻¹² W/m²
C) 2.98 × 10⁻¹² W/m²
D) 3.16 × 10⁻¹² W/m²
E) 4.25 × 10⁻¹² W/m²

Question 23

A 50 cm long organ pipe is filled with air and is open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the wavelength of the second mode?

A) 50 cm
B) 75 cm
C) 90 cm
D) 40 cm
E) 63 cm

Question 24

A 30 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the wavelength of the second mode of vibration?

A) 10 cm
B) 20 cm
C) 30 cm
D) 40 cm
E) 60 cm

Question 25

A 50.0 cm long organ pipe is filled with air and is open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the frequency of the second mode?

A) 662 Hz
B) 621 Hz
C) 587 Hz
D) 562 Hz
E) 550 Hz

Question 26

A 60.0 cm long organ pipe is filled with air and is open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the wavelength of the fundamental mode?

A) 115 cm
B) 120 cm
C) 131 cm
D) 142 cm
E) 167 cm

Question 27

A 40.0 cm long organ pipe is filled with air and is open at both ends. The speed of sound in air at 0°C is 331 m/s. If the temperature of the air decreases by 10°C, then what is the frequency of the fundamental mode?

A) 394 Hz
B) 406 Hz
C) 462 Hz
D) 506 Hz
E) 544 Hz

Question 28

The three lowest resonant frequencies of a system are 50 Hz, 150 Hz, and 250 Hz. The system could be

A) a tube of air closed at both ends.
B) a tube of air open at one end.
C) a tube of air open at both ends.
D) a vibrating string with fixed ends.

Question 29

A 60.0 cm long brass rod is suspended at the ends by long strings. The rod is struck at one end parallel to the rod and causes the rod to vibrate longitudinally with the ends free. (Y = 9.00 × 10¹⁰ N/m², density = 8,470 kg/m³.) Assuming the rod vibrates in its fundamental mode, the frequency of the vibration is

A) 3,790 Hz.
B) 3,540 Hz.
C) 3,120 Hz.
D) 2,720 Hz.
E) 2,140 Hz.

Question 30

The sound of a jet engine is given as 120 dB. What is the intensity of the jet sound wave?

A) 1.0 W/m²
B) 0.8 W/m²
C) 0.6 W/m²
D) 0.4 W/m²
E) 0.2 W/m²

Question 31

The sound of a band is rated as 50 dB at a distance of 30.0 m. What is the sound intensity level of the band when one is 10.0 m from the band?

A) 59.5 dB
B) 57.3 dB
C) 55.2 dB
D) 52.9 dB
E) 50.1 dB

Question 32

A 3.00 m organ pipe is open at both ends and contains air. The speed of sound in air is 331 m/s. What is the frequency of the lowest frequency mode?

A) 39.5 Hz
B) 40.2 Hz
C) 43.1 Hz
D) 47.5 Hz
E) 55.2 Hz

Question 33

A 30.0 cm long brass rod is suspended at the ends by long strings. The rod is struck at one end parallel to the rod and causes the rod to vibrate longitudinally with the ends free. (Y = 9.00 × 10¹⁰ N/m², density = 8,470 kg/m³.) Assuming the rod vibrates in its fundamental mode, the frequency of the vibration is

A) 5,430 Hz.
B) 5,020 Hz.
C) 4,760 Hz.
D) 4,500 Hz.
E) 3,950 Hz.

Question 34

The sound of a band is rated as 60 dB at a distance of 10.0 m. What is the sound intensity level of the band when one is 20.0 m from the band?

A) 56 dB
B) 54 dB
C) 52 dB
D) 50 dB
E) 48 dB

Question 35

A 40.0 cm long organ pipe is filled with air and is open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the frequency of the fundamental mode?

A) 297 Hz
B) 314 Hz
C) 373 Hz
D) 385 Hz
E) 414 Hz

Question 36

A 20.0 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the frequency of the fundamental mode?

A) 414 Hz
B) 387 Hz
C) 345 Hz
D) 302 Hz
E) 295 Hz

Question 37

A 30 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the wavelength of the fundamental mode?

A) 1.4 m
B) 1.6 m
C) 1.8 m
D) 1.0 m
E) 1.2 m

Question 38

A 3.0 m organ pipe is open at both ends and contains air. The speed of sound in air is 331 m/s. What is the wavelength of the lowest frequency mode?

A) 1.5 m
B) 3.0 m
C) 6.0 m
D) 9.0 m
E) 12.0 m

Question 39

A 40.0 cm long organ pipe is filled with air and is open at both ends. The speed of sound in air at 0°C is 331 m/s. If the temperature of the air increases by 10°C, then what is the frequency of the fundamental mode?

A) 367 Hz
B) 395 Hz
C) 401 Hz
D) 421 Hz
E) 480 Hz

Question 40

A 20 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the wavelength of the fundamental mode?

A) 40 cm
B) 60 cm
C) 80 cm
D) 43 cm
E) 75 cm

Question 41

There are two identical organs with pipes having fundamental frequencies of 264.0 Hz at 20°C. One organ is located at the front of the auditorium where the temperature is 20°C and one at the back where the temperature in 25.0°C. What is the beat frequency when the two organs sound this note simultaneously?

A) zero since it is the same note
B) 2.24 Hz
C) 31.2 Hz
D) 4.51 Hz

Question 42

A string with a mass per length of 2.00 g/m is stretched with a force of 120 N between two points that are 0.400 m apart. The fundamental frequency of the stretched string is in tune with the fundamental frequency of an organ pipe filled with air and open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the length of the organ pipe?

A) 54.1 cm
B) 59.0 cm
C) 61.5 cm
D) 63.5 cm
E) 66.8 cm

Question 43

A string with a mass per length of 2.00 g/m is stretched with a force of 120 N between two points that are 0.400 m apart. The fundamental frequency of the stretched string is in tune with the frequency of the second mode of an organ pipe filled with air at −20°C and open at both ends. The speed of sound in air at 0^°C is 331 m/s. What is the length of the organ pipe?

A) 75.0 cm
B) 104 cm
C) 125 cm
D) 150 cm
E) 175 cm

Question 44

A 40.0 cm long organ pipe is filled with air at 0°C and is open at both ends. The speed of sound in air at 0°C is 331 m/s. Another 40.0 cm long organ pipe is filled with air at 20°C and is open at both ends. What is the beat frequency between the fundamental modes of the two organ pipes?

A) 20.5 Hz
B) 17.5 Hz
C) 15.6 Hz
D) 14.9 Hz
E) 12.3 Hz

Question 45

A string with a mass per length of 2.00 g/m is stretched with a force of 150 N between two points that are 0.500 m apart. The fundamental frequency of the stretched string is in tune with the fundamental frequency of an organ pipe filled with air and open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the length of the organ pipe?

A) 50.2 cm
B) 55.2 cm
C) 57.5 cm
D) 60.4 cm
E) 65.3 cm

Question 46

An organ pipe is 60.0 cm long and is open at one end and closed at the other. The frequency of the third mode is 300 Hz higher than the frequency of the second mode. What is the speed of sound?

A) 280 m/s
B) 300 m/s
C) 320 m/s
D) 340 m/s
E) 360 m/s

Question 47

An ambulance is generating a siren sound at a frequency of 2,000 Hz. The speed of sound is 345.0 m/s. The observer and the ambulance are traveling toward each other at a velocity of 24.00 m/s. If the ambulance is stationary, what is the frequency of the siren perceived by the observer?

A) 2,640 Hz
B) 2,559 Hz
C) 2,324 Hz
D) 2,139 Hz
E) 2,003 Hz

Question 48

A 20.0 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the frequency of the third mode of vibration?

A) 2,900 Hz
B) 2,480 Hz
C) 2,070 Hz
D) 1,660 Hz
E) 1,240 Hz

Question 49

A 50.0 cm long organ pipe is filled with air at 10.0°C and is open at both ends. The speed of sound in air at 0°C is 331 m/s. Another 50.0 cm long organ pipe is filled with air at 15.0°C and is open at both ends. What is the beat frequency between the fundamental modes of the two organ pipes?

A) 2.96 Hz
B) 2.45 Hz
C) 2.10 Hz
D) 1.94 Hz
E) 1.77 Hz

Question 50

A string with a mass per length of 2.00 g/m is stretched with a force of 120 N between two points that are 0.400 m apart. The fundamental frequency of the stretched string is in tune with the frequency of the second mode of an organ pipe filled with air and open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the length of the organ pipe?

A) 225 cm
B) 175 cm
C) 125 cm
D) 108 cm
E) 95.0 cm

Question 51

A string with a mass per length of 2.00 g/m is stretched with a force of 150 N between two points that are 0.500 m apart. The fundamental frequency of the stretched string is in tune with the fundamental frequency of an organ pipe filled with air at 20°C and open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the length of the organ pipe?

A) 70.5 cm
B) 62.6 cm
C) 59.3 cm
D) 53.8 cm
E) 50.2 cm

Question 52

A string with a mass per length of 2.00 g/m is stretched with a force of 150 N between two points that are 0.500 m apart. The frequency of the second mode of the stretched string is in tune with the fundamental frequency of an organ pipe filled with air and open at both ends. The speed of sound in air at 0°C is 331 m/s. What is the length of the organ pipe?

A) 43.6 cm
B) 40.1 cm
C) 37.5 cm
D) 35.6 cm
E) 30.2 cm

Question 53

A 60.0 cm long organ pipe is filled with air at 15°C and is open at both ends. The speed of sound in air at 0°C is 331 m/s. Another 60.0 cm long organ pipe is filled with air at 25.0°C and is open at both ends. What is the beat frequency between the second modes of the two organ pipes?

A) 9.20 Hz
B) 9.33 Hz
C) 9.54 Hz
D) 9.75 Hz
E) 9.99 Hz

Question 54

An organ pipe is open at both ends. The frequency of the third mode is 320 Hz higher than the frequency of the second mode. If the speed of sound is 345 m/s, then what is the length of the organ pipe?

A) 64.0 cm
B) 62.6 cm
C) 57.9 cm
D) 53.9 cm
E) 50.3 cm

Question 55

An organ pipe is open at one end and closed at the other. The frequency of the third mode is 300 Hz higher than the frequency of the second mode. If the speed of sound is 345 m/s, then what is the length of the organ pipe?

A) 50.3 cm
B) 57.5 cm
C) 64.5 cm
D) 66.7 cm
E) 70.5 cm

Question 56

An organ pipe is open at both ends. The frequency of the fourth mode is 316 Hz higher than the frequency of the third mode. If the speed of sound is 340 m/s, then what is the length of the organ pipe?

A) 53.8 cm
B) 59.8 cm
C) 60.3 cm
D) 62.8 cm
E) 64.7 cm

Question 57

An organ pipe is 80.0 cm long and is open at one end and closed at the other. The frequency of the third mode is 200 Hz higher than the frequency of the second mode. What is the speed of sound?

A) 300 m/s
B) 320 m/s
C) 340 m/s
D) 360 m/s
E) 380 m/s

Question 58

A 30.0 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the wavelength of the fourth mode of vibration?

A) 30.3 cm
B) 26.7 cm
C) 21.2 cm
D) 17.1 cm
E) 12.3 cm

Question 59

A 30 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the wavelength of the third mode of vibration?

A) 48 cm
B) 36 cm
C) 30 cm
D) 24 cm
E) 12 cm

Question 60

A 25.0 cm long organ pipe is filled with air and is open at one end and closed at the other. The speed of sound in air at 0°C is 331 m/s. What is the frequency of the fourth mode of vibration?

A) 1,550 Hz
B) 1,750 Hz
C) 2,320 Hz
D) 2,720 Hz
E) 3,170 Hz

Question 61

A bat is flying toward a cave wall. If it hears reflected sound of frequency 60.9 kHz, what is its flying speed, assuming it emits sound at 52.0 kHz? The speed of sound is 341.5 m/s.

A) 25.9 m/s
B) 28.1 m/s
C) 49.9 m/s
D) 26.9 m/s
E) 58.4 m/s

Question 62

A block holding a ringing tuning fork is attached to a wall by a spring. The block oscillates back and forth on a horizontal, frictionless surface, with amplitude 17 cm. The spring constant is 390 N/m. An observer who is situated so that the block's direction of motion is either directly towards or away from him notes that the frequency he hears varies between 174 and 178 Hz. What is the mass of the tuning fork and block together? The speed of sound is 340 m/s.

A) 4.4 kg
B) 0.76 kg
C) 0.18 kg
D) 2.9 kg

Question 63

An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. The observer is traveling at a velocity of 24.00 m/s toward the ambulance and the ambulance is traveling at a velocity of 24.00 m/s away the observer. What is the frequency of the siren perceived by the observer?

A) 2,448 Hz
B) 2,424 Hz
C) 2,400 Hz
D) 2,376 Hz
E) 2,352 Hz

Question 64

A 1024 Hz tuning fork is dangled at the end of a string such that its center of mass is 1.2 m below the point at which the other end of the string is attached to door frame, making a pendulum of sorts. The tuning fork may be treated as a point mass for the purposes of this problem. The pendulum is brought to a maximum angle and released. If the range of frequencies heard by an observer standing in the plane of the pendulum's motion is 1020-1028 Hz, what is the angle to which the pendulum was raised? The speed of sound is 340 m/s.

A) 22°
B) 18°
C) 17°
D) 46°
E) 4.3°

Question 65

A block holding a ringing tuning fork is attached to a wall by a spring. The block oscillates back and forth on a horizontal, frictionless surface, with amplitude 17 cm. The mass of the tuning fork and block together is 0.75 kg. An observer who is situated so that the block's direction of motion is either directly towards or away from him notes that the frequency he hears varies between 174 and 178 Hz. What is the spring constant of the spring? The speed of sound is 340 m/s.

A) 390 N/m
B) 203 N/m
C) 1590 N/m
D) 290 N/m
E) 100 N/m

Question 66

A guitar string with a tension of 150 N is played together with a tuning fork whose frequency is 256 Hz, and beats of 2 Hz are heard. Assuming the guitar string is higher in frequency than the tuning fork, to what new tension should the guitar string be adjusted for the string and tuning fork to have the same frequency?

A) 148 N
B) 149 N
C) 151 N
D) 152 N
E) The length of the string must be given in order to solve this problem.

Question 67

An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. If the ambulance is traveling at a velocity of 24.00 m/s away from the stationary observer, then what is the frequency of the siren perceived by the observer?

A) 2,375 Hz
B) 2,306 Hz
C) 2,266 Hz
D) 2,244 Hz
E) 2,210 Hz

Question 68

A 1024 Hz tuning fork is dangled at the end of a string such that its center of mass is 1.2 m below the point at which the other end of the string is attached to door frame, making a pendulum of sorts. The tuning fork may be treated as a point mass for the purposes of this problem. If the pendulum is brought to an amplitude of 22° and released, what is the range of frequencies heard by an observer standing in the plane of the pendulum's motion? The speed of sound is 340 m/s.

A) 1015 Hz to 1033 Hz
B) 1012 Hz to 1036 Hz
C) 1010 Hz to 1038 Hz
D) 1020 Hz to 1028 Hz

Question 69

An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. If the observer is traveling at a velocity of 24.00 m/s away from the stationary ambulance, then what is the frequency of the siren perceived by the observer?

A) 2,375 Hz
B) 2,366 Hz
C) 2,305 Hz
D) 2,275 Hz
E) 2,233 Hz

Question 70

An ambulance is generating a siren sound at a frequency of 2,000 Hz. The speed of sound is 345.0 m/s. The observer and the ambulance are traveling toward each other at a velocity of 24.00 m/s. If the observer is stationary, what is the frequency of the siren perceived by the observer?

A) 2,032 Hz
B) 2,150 Hz
C) 2,220 Hz
D) 2,575 Hz
E) 2,750 Hz

Question 71

If on a given day the speed of sound increases by 1.5% between 8:00am and 11:00am, and if the temperature at 8:00am was 21°C, what was the temperature at 11:00am?

A) 21.6°C
B) 21.3°C
C) 25.4°C
D) 29.9°C

Question 72

A bat is flying toward a cave wall at 27.0 m/s. What is the frequency of the reflected sound that it hears, assuming it emits sound at 52.0 kHz? The speed of sound is 341.5 m/s.

A) 60.9 kHz
B) 56.5 kHz
C) 61.3 kHz
D) 56.1 kHz

Question 73

Pianos are usually strung with multiple identical wires sounding each note. If two wires that are each meant to have a fundamental frequency of 283.5 Hz are played, and a beat frequency of 1.5 Hz is heard, by what fraction must the string which is lower in frequency than the other have its tension adjusted?

A) 0.27%
B) 0.53%
C) Not enough information
D) 1.1%

Question 74

An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. If the observer is traveling at a velocity of 24.00 m/s toward the stationary ambulance, then what is the frequency of the siren perceived by the observer?

A) 2,640 Hz
B) 2,567 Hz
C) 2,520 Hz
D) 2,508 Hz
E) 2,475 Hz

Question 75

Two organ pipes, open at both ends, are meant to be the same length, but apparently they are not. When played simultaneously the beat frequency heard is 2.4 Hz. If the fundamental frequency of the first pipe is 228 Hz, by what fraction is the first pipe different in length than the second?

A) 2%
B) −2%
C) −1%
D) Not enough information
E) 1%

Question 76

An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. If the ambulance is traveling at a velocity of 24.00 m/s toward the stationary observer, then what is the frequency of the siren perceived by the observer?

A) 2,579 Hz
B) 2,540 Hz
C) 2,525 Hz
D) 2,500 Hz
E) 2,480 Hz

Question 77

An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. The observer is traveling at a velocity of 24.00 m/s toward the ambulance and the ambulance is traveling at a velocity of 24.00 m/s toward the observer. What is the frequency of the siren perceived by the observer?

A) 2,100 Hz
B) 2,250 Hz
C) 2,430 Hz
D) 2,550 Hz
E) 2,759 Hz

Question 78

A block holding a ringing tuning fork is attached to a wall by a spring. The block oscillates back and forth on a horizontal, frictionless surface, with amplitude 17 cm. The mass of the tuning fork and block together is 0.75 kg. An observer who is situated so that the block's direction of motion is either directly towards or away from him notes that the frequency he hears varies between 174 and 178 Hz. What is the period of motion of the block? The speed of sound is 340 m/s.

A) Cannot do without knowing the spring constant.
B) 0.28 s
C) 0.14 s
D) 0.044 s
E) 0.022 s

Question 79

The temperature is observed to decrease from 32°C to 23°C during the evening of a very hot day. What is the relative change in the speed of sound over this time interval?

A) −15%
B) −28%
C) −1.5%
D) −3%

Question 80

An ambulance is generating a siren sound at a frequency of 2,400 Hz. The speed of sound is 345.0 m/s. The observer is traveling at a velocity of 24.00 m/s toward the ambulance and the ambulance is traveling at a velocity of 20.00 m/s toward the observer. What is the frequency of the siren perceived by the observer?

A) 2,489 Hz
B) 2,560 Hz
C) 2,675 Hz
D) 2,725 Hz
E) 2,830 Hz