2 SoundSectionsProducing a Sound WaveCharacteristics of Sound WavesThe Speed of SoundSpherical and Plane WavesThe Doppler EffectInterference of Sound WavesStanding WavesStanding Waves in Air ColumnsBeats
4 Characteristics of Sound Waves Characteristics of Sound Loudness: related to intensity of the sound waveLoudness: related to intensity of the sound wavePitch: related to frequencyPitch: related to frequencyAudible range: about 20 Hz to 20,000 HzAudible range: about 20 Hz to 20,000 HzUltrasound: above 20,000 HzUltrasound: above 20,000 HzInfrasound: below 20 HzInfrasound: below 20 HzPhy 2054 Lecture Notes 12
5 Chapter 14 SoundThe pitch of a musical note is characterized by the sound’s(A) amplitude(B) frequency(C) wavelength(D) speed
6 The Speed of SoundSound can travel through any kind of matter, but not through a vacuum.Sound can travel through any kind of matter, but not through a vacuum.The speed of sound is different in different materials; in general, it is slowest in gases, faster in liquids, and fastest in solids.The speed of sound is different in different materials; in general, it is slowest in gases, faster in liquids, and fastest in solids.The speed depends somewhat on temperature, especially for gases.The speed depends somewhat on temperature, especially for gases.
7 Chapter 14 SoundWhich of the following is a true statement?(A) Sound waves are transverse pressure waves.(B) Sound waves can not travel through a vacuum.(C) Sound waves and light waves travel a the same speed.(D) When the frequency of a sound wave increases itswavelength also increases.
8 The Speed of SoundSpeed of a wave on a string.Speed of sound in a fluid.Speed of sound in a solid.Speed of sound in air is temperature dependent.
9 Chapter 14 SoundAs the temperature of the air increases, the speed of sound through the air(A) increases.(B) decreases.(C) does not change.(D) increases if the atmospheric pressure is high.
10 Chapter 14 SoundSound of a frequency f travels through air with a wavelength l. If the frequency of the sound isincreased to 2f, its wavelength in air will be
11 Spherical and Plane Waves The intensity of sound from a point source diminisheswith distance:Phy 2054 Lecture Notes 12
12 Chapter 14 SoundThe intensity of a point source at a distance d from the source is I. The intensity of the sound at a distance 2d from the source?
13 Chapter 14 SoundThe intensity of a sound increases when there is an increase in the sound’s(A) frequency(B) wavelength(C) amplitude(D) speed
14 The Doppler Effect"I love hearing that lonesome wail of the train whistle as themagnitude of the frequency of the wave changes due to theDoppler effect."Phy 2054 Lecture Notes 12
15 The Doppler EffectThe Doppler Effect for two stationary observers
16 The Doppler EffectThe Doppler effect occurs when a source of sound is moving with respect to an observer.Stationary truckLonger wavelengthLower frequencyShorter wavelengthHigher frequencyMoving truckPhy 2054 Lecture Notes 12
17 The Doppler Effect is experienced whenever there is relative motion between the soundsource and an observer.DopplerEffectPhy 2054 Lecture Notes 12
18 The Doppler Effect Stationary Source Higher Frequency Stationary ObserverHigherFrequencyPhy 2054 Lecture Notes 12
19 The Doppler Effect Stationary Source Lower Frequency Stationary ObserverLowerFrequencyPhy 2054 Lecture Notes 12
21 Chapter 14 SoundA police car with its siren on departs from a stationary observer. The frequency heard by the observer(A) is higher than the source.(B) is lower than the source.(C) is the same as that of the source.(D) is equal to zero.
22 The Doppler Effect (problem) You are standing still. What frequency do you detect if a fire engine whose siren emits at 1550 Hz moves at a speed of 32 m/sa) toward you?b) away from you?Phy 2054 Lecture Notes 12
23 The Doppler Effect (Problem) A bat flies toward a wall at a speed of 5.0 m/s. As it flies, the bat emits an ultrasonic sound wave with a frequency of 30.0 kHz.What frequency does the bat hear in the reflected wave?Phy 2054 Lecture Notes 12
24 Interference of Sound Waves Sound waves interfere in the same way that other waves do in space.
25 Sources of Sound: Vibrating Strings and Air Columns Standing WavesSources of Sound: Vibrating Strings and Air ColumnsMusical instruments produce sounds in various ways –vibrating stringsvibrating membranesvibrating metal or wood shapesvibrating air columnsMusical instruments produce sounds in various ways –vibrating stringsvibrating membranesvibrating metal or wood shapesvibrating air columnsThe vibration may be started by:pluckingstrikingbowingblowingThe vibration may be started by:pluckingstrikingbowingblowingThe vibrations are transmitted to the air and then to our ears.The vibrations are transmitted to the air and then to our ears.Phy 2054 Lecture Notes 12
26 Standing WavesThe strings on a guitar can be effectively shortened by fingering, raising the fundamental pitch.The strings on a guitar can be effectively shortened by fingering, raising the fundamental pitch.The pitch of a string of a given length can also be altered by using a string of different density.The pitch of a string of a given length can also be altered by using a string of different density.Standing WavesPhy 2054 Lecture Notes 12
27 First Harmonic - Fundamental Standing WavesFirst Harmonic - FundamentalSecond HarmonicThird HarmonicPhy 2054 Lecture Notes 12
28 Chapter 14 SoundThe standing wave on a vibrating guitar string produces a sound wave in the air. The two waves have(A) the same wavelength.(B) the same speed.(C) the same frequency.(D) the same amplitude.
29 Standing Waves in Air Columns A tube open at both ends has displacement antinodes, at the ends.LFirst Harmonic - FundamentalSecond HarmonicThird HarmonicPhy 2054 Lecture Notes 12
30 Chapter 14 SoundA pipe open at both ends resonates with a fundamental frequency of 150 Hz. Which one of the following frequencies will not resonate in this pipe(A) 300 Hz(B) 450 Hz(C) 500 Hz(D) 750 Hz
31 Standing Waves in Air Columns (Problem) A uniform narrow tube 1.8 m long is open at both ends. It resonates at two successive harmonics of frequencies 275 Hz and 330 Hz. What is the speed of sound in the gas in the tube?Phy 2054 Lecture Notes 12
32 Standing Waves in Air Columns A tube closed at one end has a displacement node at the closed end.LFirst Harmonic - FundamentalThird HarmonicFifth HarmonicPhy 2054 Lecture Notes 12
33 Chapter 14 SoundA pipe open at one end and closed at the other end. resonates with a fundamental frequency of 150 Hz. Which one of the following frequencies will notresonate in this pipe(A) 300 Hz(B) 450 Hz(C) 760 Hz(D) 1050 Hz
36 Chapter 12 SoundThe interference of two sound waves can produces a beat frequency if the waves have(A) the same amplitude.(B) slightly different amplitudes.(C) the same frequency.(D) slightly different frequencies.
37 Chapter 12 SoundTwo pure tones are sounded together and a particular beat frequency is heard. If the frequency of one of the tones is decreased slightly, the beat frequency(A) will increases.(B) will decreases.(C) does not change.(D) could either increase or decrease.