Chapter 12 Sound

14-01 Producing a Sound Wave Characteristics of Sound Waves The Speed of Sound Spherical and Plane Waves The Doppler Effect Interference of Sound Waves Standing Waves Sound Sections Standing Waves in Air Columns Beats Sound (02 of 38)

Producing a Sound Wave Sound (03 of 38)

Characteristics of Sound u Loudness: related to intensity of the sound wave u Pitch: related to frequency u Audible range: about 20 Hz to 20,000 Hz u Ultrasound: above 20,000 Hz u Infrasound: below 20 Hz u Loudness: related to intensity of the sound wave u Pitch: related to frequency u Audible range: about 20 Hz to 20,000 Hz u Ultrasound: above 20,000 Hz u Infrasound: below 20 Hz Characteristics of Sound Waves Sound (04 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 The pitch of a musical note is characterized by the sound’s (A) amplitude (B) frequency (C) wavelength (DE) speed Sound (05 of 38)

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 depends somewhat on temperature, especially for gases. 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 depends somewhat on temperature, especially for gases. The Speed of Sound Sound (06 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 Which 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 its wavelength also increases. Sound (07 of 38)

The Speed of Sound Speed 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. Sound (08 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 As 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. Sound (09 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 Sound of a frequency f travels through air with a wavelength. If the frequency of the sound is increased to 2f, its wavelength in air will be Sound (10 of 38)

Spherical and Plane Waves The intensity of sound from a point source diminishes with distance: Sound (11 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 The 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? Sound (12 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 The intensity of a sound increases when there is an increase in the sound’s (A) frequency (B) wavelength (C) amplitude (D) speed Sound (13 of 38)

"I love hearing that lonesome wail of the train whistle as the magnitude of the frequency of the wave changes due to the Doppler effect." The Doppler Effect Sound (14 of 38)

The Doppler Effect The Doppler Effect for two stationary observers Sound (15 of 38)

The Doppler effect occurs when a source of sound is moving with respect to an observer. Stationary truck Moving truck Longer wavelength Lower frequency Shorter wavelength Higher frequency The Doppler Effect Sound (16 of 38)

Doppler Effect is experienced whenever there is relative motion between the sound source and an observer. The Doppler Effect Sound (17 of 38)

Stationary Source Higher Frequency Stationary Observer Higher Frequency The Doppler Effect Sound (18 of 38)

Stationary Source Lower Frequency Stationary Observer Lower Frequency The Doppler Effect Sound (19 of 38)

The Doppler Effect Sound (20 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 A 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. Sound (21 of 38)

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/s a) toward you? b) away from you? The Doppler Effect (problem) Sound (22 of 38)

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? The Doppler Effect (Problem) Sound (23 of 38)

Interference of Sound Waves Sound waves interfere in the same way that other waves do in space. Sound (24 of 38)

Sources of Sound: Vibrating Strings and Air Columns Musical instruments produce sounds in various ways – vibrating strings vibrating membranes vibrating metal or wood shapes vibrating air columns The vibrations are transmitted to the air and then to our ears. The vibration may be started by: plucking striking bowing blowing Musical instruments produce sounds in various ways – vibrating strings vibrating membranes vibrating metal or wood shapes vibrating air columns The vibrations are transmitted to the air and then to our ears. The vibration may be started by: plucking striking bowing blowing Standing Waves Sound (25 of 38)

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 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. Standing Waves Sound (26 of 38)

First Harmonic - Fundamental Second Harmonic Third Harmonic Standing Waves Sound (27 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 The 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. Sound (28 of 38)

A tube open at both ends has displacement antinodes, at the ends. First Harmonic - Fundamental L Second Harmonic Third Harmonic Standing Waves in Air Columns Sound (29 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 A 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 Sound (30 of 38)

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? Standing Waves in Air Columns (Problem) Sound (31 of 38)

A tube closed at one end has a displacement node at the closed end. L First Harmonic - Fundamental Third Harmonic Fifth Harmonic Standing Waves in Air Columns Sound (32 of 38)

Chapter 14 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 A 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 not resonate in this pipe (A) 300 Hz (B) 450 Hz (C) 750 Hz (D) 1050 Hz Sound (33 of 38)

Standing Waves in Air Columns Sound (34 of 38)

Beats Beat Frequency Sound (35 of 38)

Chapter 12 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 The 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. Sound (36 of 38)

Chapter 12 Sound ~M1~M2~M3~M4~M5~M6~M7~M8~M10 ~M9 ~M11~M12~M13~M14~M15~M16~M17~M18~M20 ~M19 ~M21~M22~M23~M24~M25~M26~M27~M28~M30 ~M29 ~M31~M32~M33~M34~M35~M36~M37~M38~M40 ~M39 ~M41~M42~M43~M44~M45~M46~M47~M48~M50 ~M49 ~M51~M52~M53~M54~M55~M56~M57~M58~M60 ~M59 Two 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. Sound (37 of 38)

The End