Question 1

A sound intensity of 70 dB is observed at a distance d from the source of sound.What sound intensity would be observed at a distance 2d from the source?

Accepted Answer

A)  68 dB 
B)  67 dB 
C)  64 dB 
D)  62 dB 
A)  68 dB 
B)  67 dB 
C)  64 dB 
D)  62 dB C

Question 2

The density of a certain solid is 7.2 × 103 kg/m3,and its Young's modulus is 8.0 × 1010 N/m2.What is the speed of sound in this material?

Accepted Answer

A)  1.1 × 107 m/s 
B)  5900 m/s 
C)  3700 m/s 
D)  3300 m/s 
A)  1.1 × 107 m/s 
B)  5900 m/s 
C)  3700 m/s 
D)  3300 m/s D

Question 3

When one note is above another note by an octave,the frequency of the higher pitch note is double that of the lower pitch note.The word octave may make you think that there are 8 steps from the lower note to the one an octave above.But wait! How many steps are there on a piano from middle C to the next C above? Each key is a step.If each next key is a step,how many are there? Middle C is a white (W)key and the next note above is a black (B)key.Starting at middle C on the piano the sequence of key we go through to get to high C,is BWBWWBWBWBWW,the last key being high C.Count 'em.That's 12 steps.If the multiplying factor of the frequency for the next step is the same for each step,what is that multiplying frequency? All you need is given in this problem statement.

Accepted Answer

A)  101/12 
B)  121/8 
C)  21/8 
D)  21/12 
A)  101/12 
B)  121/8 
C)  21/8 
D)  21/12 D

Question 4

In the afternoon,the decibel level of a busy freeway is 80 dB with 100 cars passing a given point every minute.Late at night,the traffic flow is only 8 cars per minute.What is the late-night decibel level?

Accepted Answer

A)  77 dB 
B)  74 dB 
C)  70 dB 
D)  69 dB 
A)  77 dB 
B)  74 dB 
C)  70 dB 
D)  69 dB

Question 5

Material 1 has Young's modulus Y1 and density ρ​1,and material 2 has Young's modulus Y​2 and density ρ2.If Y1 is 30% more than Y​2 and ρ​1 is 30% less than ρ2,which material has the higher speed of sound and how much higher is it?

Accepted Answer

A)  Material 1 has a speed of sound more than 35% higher than material 2. 
B)  Material 1 has a speed of sound 30% higher than material 2. 
C)  Material 2 has a speed of sound more than 80% higher than material 1. 
D)  Material 2 has a speed of sound 30% higher than material 1. 
A)  Material 1 has a speed of sound more than 35% higher than material 2. 
B)  Material 1 has a speed of sound 30% higher than material 2. 
C)  Material 2 has a speed of sound more than 80% higher than material 1. 
D)  Material 2 has a speed of sound 30% higher than material 1.

Question 6

The frequency separating audible waves and ultrasonic waves is considered to be 20 kHz.What wavelength in air at room temperature is associated with this frequency? (Assume the speed of sound to be 340 m/s. )

Accepted Answer

A)  0.59 cm 
B)  1.7 cm 
C)  34 cm 
D)  55 cm 
A)  0.59 cm 
B)  1.7 cm 
C)  34 cm 
D)  55 cm

Question 7

Which of the following best describes a sound level of intensity 10-6 W/m2?

Accepted Answer

A)  extremely loud 
B)  about that of a power mower 
C)  normal conversation 
D)  like a whisper 
A)  extremely loud 
B)  about that of a power mower 
C)  normal conversation 
D)  like a whisper

Question 8

A train station bell gives off a fundamental tone of 1000 Hz as the train approaches the station at a speed of 20.0 m/s.If the speed of sound in air is 335 m/s,what will be the apparent frequency of the bell to an observer riding the train?

Accepted Answer

A)  1060 Hz 
B)  1070 Hz 
C)  943 Hz 
D)  940 Hz 
A)  1060 Hz 
B)  1070 Hz 
C)  943 Hz 
D)  940 Hz

Question 9

Two vibrating tuning forks,held side by side,will create a beat frequency of what value if the individual frequencies of the two forks are 321 Hz and 326 Hz,respectively?

Accepted Answer

A)  323.5 Hz 
B)  647 Hz 
C)  5 Hz 
D)  2.5 Hz 
A)  323.5 Hz 
B)  647 Hz 
C)  5 Hz 
D)  2.5 Hz

Question 10

The intensity level of sound 30 m from a jet airliner is 120 dB.At what distance from the airplane will the sound intensity level be a tolerable 100 dB? (Assume spherical spreading of sound. )

Accepted Answer

A)  60 m 
B)  90 m 
C)  300 m 
D)  400 m 
A)  60 m 
B)  90 m 
C)  300 m 
D)  400 m

Question 11

Doubling the distance between sound source and a listener will change the intensity,as detected by the listener,by what factor?

Accepted Answer

A)  4 
B)  2 
C)  1/2 
D)  1/4 
A)  4 
B)  2 
C)  1/2 
D)  1/4

Question 12

If the distance between a point sound source and a dB detector is increased by a factor of 10,what will be the reduction in intensity level?

Accepted Answer

A)  10 dB 
B)  16 dB 
C)  20 dB 
D)  32 dB 
A)  10 dB 
B)  16 dB 
C)  20 dB 
D)  32 dB

Question 13

What is the intensity level of a sound with intensity of 5.0 × 10−11 W/m2? (I0 = 10−12 W/m2)

Accepted Answer

A)  74 dB 
B)  54 dB 
C)  17 dB 
D)  27 dB 
A)  74 dB 
B)  54 dB 
C)  17 dB 
D)  27 dB

Question 14

A sound wave coming from a tuba has a wavelength of 0.674 m and travels to your ears at a speed of 345 m/s.What is the frequency of the sound you hear?

Accepted Answer

A)  512 Hz 
B)  1/517 Hz 
C)  230 Hz 
D)  1/230 Hz 
A)  512 Hz 
B)  1/517 Hz 
C)  230 Hz 
D)  1/230 Hz

Question 15

What is the lowest frequency that will resonate in an organ pipe 1.00 m in length,closed at one end? The speed of sound in air is 340 m/s.

Accepted Answer

A)  42.5 Hz 
B)  85.0 Hz 
C)  170 Hz 
D)  680 Hz 
A)  42.5 Hz 
B)  85.0 Hz 
C)  170 Hz 
D)  680 Hz

Question 16

A plane is traveling at Mach 0.980 through air at a temperature of 0°C.What is the plane's speed? (Speed of sound at 0°C is 331 m/s. )

Accepted Answer

A)  314 m/s 
B)  324 m/s 
C)  348 m/s 
D)  Mach number is undefined at 0°C. 
A)  314 m/s 
B)  324 m/s 
C)  348 m/s 
D)  Mach number is undefined at 0°C.

Question 17

A 500-Hz whistle is moved toward a listener at a speed of 10.0 m/s.At the same time,the listener moves at a speed of 20.0 m/s in a direction toward the whistle.What is the apparent frequency heard by the listener? (The speed of sound is 340 m/s. )

Accepted Answer

A)  473 Hz 
B)  485 Hz 
C)  533 Hz 
D)  545 Hz 
A)  473 Hz 
B)  485 Hz 
C)  533 Hz 
D)  545 Hz

Question 18

A chamber that can be filled with different gases has placed in it a source of sound that in air produces a frequency of 200 Hz and a microphone to pick up the sound for frequency analysis.First the chamber is filled with helium (speed of sound 1 000 m/s at room conditions),then the helium is replaced with oxygen (speed of sound 330 m/s at room conditions),and then finally the helium is replaced with carbon dioxide (speed of sound 269 m/s at room conditions).In which gas is the highest frequency of sound found by the microphone during this experiment?

Accepted Answer

A)  helium 
B)  oxygen 
C)  carbon dioxide 
D)  They all have the same frequency of sound. 
A)  helium 
B)  oxygen 
C)  carbon dioxide 
D)  They all have the same frequency of sound.

Question 19

How far away is a lightning strike if you hear the thunderclap 2.00 s after you see the lightning bolt strike? (vsound = 340 m/s,vlight = 3 × 108 m/s)

Accepted Answer

A)  113 m 
B)  340 m 
C)  680 m 
D)  1020 m 
A)  113 m 
B)  340 m 
C)  680 m 
D)  1020 m

Question 20

If the intensity of a sound is increased by a factor of 1000,how is the decibel level changed? The new decibel level will be:

Accepted Answer

A)  three units greater. 
B)  ten times greater. 
C)  thirty times greater. 
D)  twenty units greater. 
A)  three units greater. 
B)  ten times greater. 
C)  thirty times greater. 
D)  twenty units greater.

Exam 13: Vibrations and Waves: Part A

A sound intensity of 70 dB is observed at a distance d from the source of sound.What sound intensity would be observed at a distance 2d from the source?

The density of a certain solid is 7.2 × 103 kg/m3,and its Young's modulus is 8.0 × 1010 N/m2.What is the speed of sound in this material?

In the afternoon,the decibel level of a busy freeway is 80 dB with 100 cars passing a given point every minute.Late at night,the traffic flow is only 8 cars per minute.What is the late-night decibel level?

Material 1 has Young's modulus Y1 and density ρ​1,and material 2 has Young's modulus Y​2 and density ρ2.If Y1 is 30% more than Y​2 and ρ​1 is 30% less than ρ2,which material has the higher speed of sound and how much higher is it?

The frequency separating audible waves and ultrasonic waves is considered to be 20 kHz.What wavelength in air at room temperature is associated with this frequency? (Assume the speed of sound to be 340 m/s. )

Which of the following best describes a sound level of intensity 10-6 W/m2?

A train station bell gives off a fundamental tone of 1000 Hz as the train approaches the station at a speed of 20.0 m/s.If the speed of sound in air is 335 m/s,what will be the apparent frequency of the bell to an observer riding the train?

Two vibrating tuning forks,held side by side,will create a beat frequency of what value if the individual frequencies of the two forks are 321 Hz and 326 Hz,respectively?

The intensity level of sound 30 m from a jet airliner is 120 dB.At what distance from the airplane will the sound intensity level be a tolerable 100 dB? (Assume spherical spreading of sound. )

Doubling the distance between sound source and a listener will change the intensity,as detected by the listener,by what factor?

If the distance between a point sound source and a dB detector is increased by a factor of 10,what will be the reduction in intensity level?

What is the intensity level of a sound with intensity of 5.0 × 10−11 W/m2? (I0 = 10−12 W/m2)

A sound wave coming from a tuba has a wavelength of 0.674 m and travels to your ears at a speed of 345 m/s.What is the frequency of the sound you hear?

What is the lowest frequency that will resonate in an organ pipe 1.00 m in length,closed at one end? The speed of sound in air is 340 m/s.

A plane is traveling at Mach 0.980 through air at a temperature of 0°C.What is the plane's speed? (Speed of sound at 0°C is 331 m/s. )

A 500-Hz whistle is moved toward a listener at a speed of 10.0 m/s.At the same time,the listener moves at a speed of 20.0 m/s in a direction toward the whistle.What is the apparent frequency heard by the listener? (The speed of sound is 340 m/s. )

How far away is a lightning strike if you hear the thunderclap 2.00 s after you see the lightning bolt strike? (vsound = 340 m/s,vlight = 3 × 108 m/s)

If the intensity of a sound is increased by a factor of 1000,how is the decibel level changed? The new decibel level will be:

Introduction

Introduction: Part A

Motion in One Dimension

Motion in One Dimension: Part A

Vectors and Two-Dimensional Motion

Vectors and Two-Dimensional Motion: Part A

The Laws of Motion

The Laws of Motion: Part A

Energy

Energy: Part A

Momentum and Collisions

Momentum and Collisions: Part A

Rotational Motion and the Law of Gravity

Rotational Motion and the Law of Gravity: Part A

Rotational Equilibrium and Rotational Dynamics

Rotational Equilibrium and Rotational Dynamics: Part A

Solids and Fluids

Solids and Fluids: Part A

Thermal Physics

Thermal Physics: Part A

Energy in Thermal Processes Heat and Internal Energy

Energy in Thermal Processes Heat and Internal Energy: Part A

The Laws of Thermodynamics Work in Thermodynamic Processes

The Laws of Thermodynamics Work in Thermodynamic Processes: Part A

Vibrations and Waves

Sound

Sound: Part A

Electric Forces and Electric Fields

Electric Forces and Electric Fields: Part A

Electrical Energy and Capacitance

Electrical Energy and Capacitance: Part A

Current and Resistance Electric Current

Current and Resistance Electric Current: Part A

Direct-Current Circuits Sources of EMF

Direct-Current Circuits Sources of EMF: Part A

Magnetism Magnets

Magnetism Magnets: Part A

Induced Voltages and Inductance

Induced Voltages and Inductance: Part A

Alternating-Current Circuits and Electromagnetic Waves

Alternating-Current Circuits and Electromagnetic Waves: Part A

Reflection and Refraction of Light

Reflection and Refraction of Light: Part A

Mirrors and Lenses

Mirrors and Lenses: Part A

Wave Optics

Wave Optics: Part A

Optical Instruments

Optical Instruments: Part A

Relativity

Relativity: Part A

Quantum Physics Blackbody Radiation and Plancks Hypothesis

Quantum Physics Blackbody Radiation and Plancks Hypothesis: Part A

Atomic Physics

Atomic Physics: Part A

Nuclear Physics

Nuclear Physics: Part A

Nuclear Energy and Elementary Particles

Nuclear Energy and Elementary Particles: Part A

Particle Collisions, Mediating Photons, and Quark Structures: Exploring the Fundamentals of Physics

Filters

The density of a certain solid is 7.2 × 10³ kg/m³,and its Young's modulus is 8.0 × 10¹⁰ N/m².What is the speed of sound in this material?

Material 1 has Young's modulus Y₁ and density ρ₁,and material 2 has Young's modulus Y₂and density ρ₂.If Y₁ is 30% more than Y₂ and ρ₁ is 30% less than ρ₂,which material has the higher speed of sound and how much higher is it?

Which of the following best describes a sound level of intensity 10^-6 W/m²?

What is the intensity level of a sound with intensity of 5.0 × 10−¹¹ W/m²? (I₀ = 10−¹² W/m²)

How far away is a lightning strike if you hear the thunderclap 2.00 s after you see the lightning bolt strike? (v_sound = 340 m/s,v_light = 3 × 10⁸ m/s)