Question 1

How far away is a lightning bolt if it takes 10 s for the sound of the associated thunder to reach the observer?

Accepted Answer

A)  1 mile 
B)  2 miles 
C)  5 miles 
D)  10 miles 
E)  ​3.4 miles 
A)  1 mile 
B)  2 miles 
C)  5 miles 
D)  10 miles 
E)  ​3.4 miles B

Question 2

What sound level change corresponds to a factor of five change in intensity?

Accepted Answer

A)  0.5 dB 
B)  5 dB 
C)  7 dB 
D)  16 dB 
E)  ​50 dB 
A)  0.5 dB 
B)  5 dB 
C)  7 dB 
D)  16 dB 
E)  ​50 dB C

Question 3

A tuning fork is sounded above a resonating tube (one end closed),which resonates at a length of 0.3 m and again at 0.9 m.If the tube length were extended further,at what point will the tuning fork again create a resonance condition?

Accepted Answer

A)  1.2 m 
B)  1.5 m 
C)  1.8 m 
D)  2.4 m 
E)  ​4.8 m 
A)  1.2 m 
B)  1.5 m 
C)  1.8 m 
D)  2.4 m 
E)  ​4.8 m B

Question 4

If one-half of the members of a symphony orchestra are absent because of head colds,thus reducing the overall intensity of sound by 50%,what will be the reduction in the decibel level?

Accepted Answer

A)  17.0 dB 
B)  20.0 dB 
C)  6.9 dB 
D)  3.0 dB 
E)  ​6.9 dB 
A)  17.0 dB 
B)  20.0 dB 
C)  6.9 dB 
D)  3.0 dB 
E)  ​6.9 dB

Question 5

A buzzer with frequency f0 is thrown straight upwards.On the buzzer's trip down,what is the frequency behavior heard by an observer below?

Accepted Answer

A)  The frequency heard is still f0. 
B)  The frequency is a constant one greater than f0. 
C)  The frequency is an increasing one greater than f0. 
D)  The frequency is a decreasing one less than f0. 
A)  The frequency heard is still f0. 
B)  The frequency is a constant one greater than f0. 
C)  The frequency is an increasing one greater than f0. 
D)  The frequency is a decreasing one less than f0.

Question 6

What is the intensity level of a sound with intensity of 9.0 × 10−10 W/m2? ( I0 = 10−12 W/m2 )

Accepted Answer

A)  20 dB 
B)  68 dB 
C)  3.0 dB 
D)  30 dB 
E)  ​6.8 dB 
A)  20 dB 
B)  68 dB 
C)  3.0 dB 
D)  30 dB 
E)  ​6.8 dB

Question 7

If a guitar string has a fundamental frequency of 543 Hz,what is the frequency of its fourth overtone?

Accepted Answer

A)  135.75 Hz 
B)  678.75 Hz 
C)  2,172 Hz 
D)  2,715 Hz 
E)  ​543 Hz 
A)  135.75 Hz 
B)  678.75 Hz 
C)  2,172 Hz 
D)  2,715 Hz 
E)  ​543 Hz

Question 8

The air in a pipe resonates at 130 Hz and 390 Hz,one of these resonances being the fundamental.If the pipe is open at both ends,how many resonances are between the two given ones,and if the pipe is closed at one end,how many resonances are between the two given ones?

Accepted Answer

A)  open: 1;closed: 0 
B)  open: 0;closed: 1 
C)  open: 2;closed: 0 
D)  open: 0;closed: 2 
E)  ​open: 3;closed: 0 
A)  open: 1;closed: 0 
B)  open: 0;closed: 1 
C)  open: 2;closed: 0 
D)  open: 0;closed: 2 
E)  ​open: 3;closed: 0

Question 9

A sound wave in air has a frequency of 470 Hz and a wavelength of 0.65 m.What is the air temperature?

Accepted Answer

A)  -4°C 
B)  0°C 
C)  -43°C 
D)  -25.8°C​ 
E)  ​106°C 
A)  -4°C 
B)  0°C 
C)  -43°C 
D)  -25.8°C​ 
E)  ​106°C

Question 10

In the afternoon,the decibel level of a busy freeway is 85 dB with 90 cars passing a given point every minute.Late at night,the traffic flow is only 9 cars per minute.What is the late-night decibel level?

Accepted Answer

A)  196 dB 
B)  85 dB 
C)  173 dB 
D)  75 dB 
E)  ​9 dB 
A)  196 dB 
B)  85 dB 
C)  173 dB 
D)  75 dB 
E)  ​9 dB

Question 11

When I stand halfway between two speakers,with one on my left and one on my right,a musical note from the speakers gives me constructive interference.How far to my left should I move to obtain destructive interference?

Accepted Answer

A)  one-fourth of a wavelength 
B)  half a wavelength 
C)  one wavelength 
D)  one and a half wavelengths 
A)  one-fourth of a wavelength 
B)  half a wavelength 
C)  one wavelength 
D)  one and a half wavelengths

Question 12

An airplane flying with a constant speed flies from a warm air mass into a cold air mass.The Mach number will:

Accepted Answer

A)  increase. 
B)  decrease. 
C)  stay the same. 
D)  become unstable. 
A)  increase. 
B)  decrease. 
C)  stay the same. 
D)  become unstable.

Question 13

If the tension on a guitar string is increased by a factor of 2,the fundamental frequency at which it vibrates is changed by what factor?

Accepted Answer

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

Question 14

By what amount does the sound intensity decrease when the distance to the source triples?

Accepted Answer

A)  1.9 dB 
B)  3 dB 
C)  9 dB 
D)  10 dB 
E)  ​0.11 dB 
A)  1.9 dB 
B)  3 dB 
C)  9 dB 
D)  10 dB 
E)  ​0.11 dB

Question 15

The speed of sound in air is a function of which one of the following?

Accepted Answer

A)  wavelength 
B)  frequency 
C)  temperature 
D)  amplitude 
A)  wavelength 
B)  frequency 
C)  temperature 
D)  amplitude

Question 16

A very loud train whistle has an acoustic power output of 94 W.If the sound energy spreads out spherically,what is the intensity level in dB at a distance of 95 meters from the train? (I0 = 10−12 W/m2)

Accepted Answer

A)  21 dB 
B)  69 dB 
C)  89 dB 
D)  94 dB 
E)  205 dB 
A)  21 dB 
B)  69 dB 
C)  89 dB 
D)  94 dB 
E)  205 dB

Question 17

A C note (f = 256 Hz)is sounded on a piano.If the length of the piano wire is 2 m and its mass density is 2.2 g/m,what is the tension in the wire?

Accepted Answer

A)  61 N 
B)  128 N 
C)  2,307 N 
D)  1,126 N 
E)  ​563 N 
A)  61 N 
B)  128 N 
C)  2,307 N 
D)  1,126 N 
E)  ​563 N

Question 18

A tuning fork is sounded above a resonating tube (one end closed),which resonates at a length of 0.3 m and again at 0.9 m.What is the frequency of the fork when the speed of sound is taken to be 340 m/s?

Accepted Answer

A)  378 Hz 
B)  283 Hz 
C)  1,133 Hz 
D)  567 Hz 
E)  ​408 Hz 
A)  378 Hz 
B)  283 Hz 
C)  1,133 Hz 
D)  567 Hz 
E)  ​408 Hz

Question 19

How far away is a lightning strike if you hear the thunderclap 8 s after you see the lightning bolt strike? (vsound = 340 m/s,vlight = 3 × 108 m/s)

Accepted Answer

A)  43 m 
B)  340 m 
C)  2,380 m 
D)  2,720 m 
E)  ​24 × 108 m/s 
A)  43 m 
B)  340 m 
C)  2,380 m 
D)  2,720 m 
E)  ​24 × 108 m/s

Question 20

The speed of sound at 0°C is 331 m/s.What is the speed of sound at 25°C? (0°C = 273 K)

Accepted Answer

A)  346 m/s 
B)  317 m/s 
C)  316 m/s 
D)  321 m/s 
E)  ​1,094 m/s 
A)  346 m/s 
B)  317 m/s 
C)  316 m/s 
D)  321 m/s 
E)  ​1,094 m/s

Exam 14: Sound

How far away is a lightning bolt if it takes 10 s for the sound of the associated thunder to reach the observer?

What sound level change corresponds to a factor of five change in intensity?

A tuning fork is sounded above a resonating tube (one end closed),which resonates at a length of 0.3 m and again at 0.9 m.If the tube length were extended further,at what point will the tuning fork again create a resonance condition?

If one-half of the members of a symphony orchestra are absent because of head colds,thus reducing the overall intensity of sound by 50%,what will be the reduction in the decibel level?

A buzzer with frequency f0 is thrown straight upwards.On the buzzer's trip down,what is the frequency behavior heard by an observer below?

What is the intensity level of a sound with intensity of 9.0 × 10−10 W/m2? ( I0 = 10−12 W/m2 )

If a guitar string has a fundamental frequency of 543 Hz,what is the frequency of its fourth overtone?

The air in a pipe resonates at 130 Hz and 390 Hz,one of these resonances being the fundamental.If the pipe is open at both ends,how many resonances are between the two given ones,and if the pipe is closed at one end,how many resonances are between the two given ones?

A sound wave in air has a frequency of 470 Hz and a wavelength of 0.65 m.What is the air temperature?

In the afternoon,the decibel level of a busy freeway is 85 dB with 90 cars passing a given point every minute.Late at night,the traffic flow is only 9 cars per minute.What is the late-night decibel level?

When I stand halfway between two speakers,with one on my left and one on my right,a musical note from the speakers gives me constructive interference.How far to my left should I move to obtain destructive interference?

An airplane flying with a constant speed flies from a warm air mass into a cold air mass.The Mach number will:

If the tension on a guitar string is increased by a factor of 2,the fundamental frequency at which it vibrates is changed by what factor?

By what amount does the sound intensity decrease when the distance to the source triples?

The speed of sound in air is a function of which one of the following?

A very loud train whistle has an acoustic power output of 94 W.If the sound energy spreads out spherically,what is the intensity level in dB at a distance of 95 meters from the train? (I0 = 10−12 W/m2)

A C note (f = 256 Hz)is sounded on a piano.If the length of the piano wire is 2 m and its mass density is 2.2 g/m,what is the tension in the wire?

A tuning fork is sounded above a resonating tube (one end closed),which resonates at a length of 0.3 m and again at 0.9 m.What is the frequency of the fork when the speed of sound is taken to be 340 m/s?

How far away is a lightning strike if you hear the thunderclap 8 s after you see the lightning bolt strike? (vsound = 340 m/s,vlight = 3 × 108 m/s)

The speed of sound at 0°C is 331 m/s.What is the speed of sound at 25°C? (0°C = 273 K)

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

Vibrations and Waves: Part A

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

A buzzer with frequency f₀ is thrown straight upwards.On the buzzer's trip down,what is the frequency behavior heard by an observer below?

What is the intensity level of a sound with intensity of 9.0 × 10−¹⁰ W/m²? ( I₀ = 10−¹² W/m²)

A very loud train whistle has an acoustic power output of 94 W.If the sound energy spreads out spherically,what is the intensity level in dB at a distance of 95 meters from the train? (I₀ = 10−¹² W/m²)

How far away is a lightning strike if you hear the thunderclap 8 s after you see the lightning bolt strike? (v_sound = 340 m/s,v_light = 3 × 10⁸ m/s)