Question 1

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?

Accepted Answer

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

Question 2

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?

Accepted Answer

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

Question 3

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

Accepted Answer

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 
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 4

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?

Accepted Answer

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

Question 5

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?

Accepted Answer

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

Question 6

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?

Accepted Answer

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 
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

Question 7

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?

Accepted Answer

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 
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 8

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?

Accepted Answer

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 
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 9

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.

Accepted Answer

A)  22° 
B)  18° 
C)  17° 
D)  46° 
E)  4.3° 
A)  22° 
B)  18° 
C)  17° 
D)  46° 
E)  4.3°

Question 10

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

Accepted Answer

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 
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 11

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?

Accepted Answer

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

Question 12

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.

Accepted Answer

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

Question 13

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?

Accepted Answer

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

Question 14

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.

Accepted Answer

A)  Cannot do without knowing the spring constant. 
B)  0.28 s 
C)  0.14 s 
D)  0.044 s 
E)  0.022 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 15

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?

Accepted Answer

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

Question 16

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?

Accepted Answer

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

Question 17

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.

Accepted Answer

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

Question 18

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

Accepted Answer

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. 
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 19

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?

Accepted Answer

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

Question 20

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?

Accepted Answer

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

Exam 12: Sound

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 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?

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

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?

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?

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?

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

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 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?

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 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.

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

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?

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?

Introduction

Motion Along a Line

Motion in a Plane

Force and Newtons Laws of Motion

Circular Motion

Conservation of Energy

Linear Momentum

Torque and Angular Momentum

Fluids

Elasticity and Oscillations

Waves

Temperature and the Ideal Gas

Heat

Thermodynamics

Electric Forces and Fields

Electric Potential

Electric Current and Circuits

Magnetic Forces and Fields

Electromagnetic Induction

Alternating Current

Electromagnetic Waves

Reflection and Refraction of Light

Optical Instruments

Interference and Diffraction

Relativity

Early Quantum Physics and the Photon

Quantum Physics

Nuclear Physics

Particle Physics

Filters

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?

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?

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?