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Chapter 14 Sound

Chapter 14 Sound. AP Physics B Lecture Notes. Sound. Sections. 14-01 Producing a Sound Wave. 14-02 Characteristics of Sound Waves. 14-03 The Speed of Sound. 14-05 Spherical and Plane Waves. 14-06 The Doppler Effect. 14-07 Interference of Sound Waves. 14-08 Standing Waves.

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Chapter 14 Sound

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  1. Chapter 14 Sound AP Physics B Lecture Notes

  2. Sound Sections 14-01 Producing a Sound Wave 14-02 Characteristics of Sound Waves 14-03 The Speed of Sound 14-05 Spherical and Plane Waves 14-06 The Doppler Effect 14-07 Interference of Sound Waves 14-08 Standing Waves 14-10 Standing Waves in Air Columns 14-11 Beats

  3. Producing a Sound Wave

  4. Characteristics of Sound Waves Characteristics of Sound • Loudness: related to intensity of the sound wave • Loudness: related to intensity of the sound wave • Pitch: related to frequency • Pitch: related to frequency • Audible range: about 20 Hz to 20,000 Hz • Audible range: about 20 Hz to 20,000 Hz • Ultrasound: above 20,000 Hz • Ultrasound: above 20,000 Hz • Infrasound: below 20 Hz • Infrasound: below 20 Hz Phy 2054 Lecture Notes 12

  5. Chapter 14 Sound The pitch of a musical note is characterized by the sound’s (A) amplitude (B) frequency (C) wavelength (D) speed

  6. The Speed of Sound Sound 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 Sound 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.

  8. 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.

  9. Chapter 14 Sound 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.

  10. Chapter 14 Sound Sound of a frequency f travels through air with a wavelength l. If the frequency of the sound is increased to 2f, its wavelength in air will be

  11. Spherical and Plane Waves The intensity of sound from a point source diminishes with distance: Phy 2054 Lecture Notes 12

  12. Chapter 14 Sound 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?

  13. Chapter 14 Sound The 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 the magnitude of the frequency of the wave changes due to the Doppler effect." Phy 2054 Lecture Notes 12

  15. The Doppler Effect The Doppler Effect for two stationary observers

  16. The Doppler Effect Stationary truck Longer wavelength Lower frequency Shorter wavelength Higher frequency The Doppler effect occurs when a source of sound is moving with respect to an observer. Moving truck Phy 2054 Lecture Notes 12

  17. The Doppler Effect is experienced whenever there is relative motion between the sound source and an observer. Doppler Effect Phy 2054 Lecture Notes 12

  18. The Doppler Effect Stationary Source Higher Frequency Stationary Observer Higher Frequency Phy 2054 Lecture Notes 12

  19. The Doppler Effect Stationary Source Lower Frequency Stationary Observer Lower Frequency Phy 2054 Lecture Notes 12

  20. The Doppler Effect Phy 2054 Lecture Notes 12

  21. Chapter 14 Sound 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.

  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/s a) 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. Standing Waves Musical instruments produce sounds in various ways – Musical instruments produce sounds in various ways – vibrating strings vibrating strings vibrating metal or wood shapes vibrating metal or wood shapes vibrating membranes vibrating membranes vibrating air columns vibrating air columns The vibration may be started by: The vibration may be started by: plucking plucking bowing bowing striking striking blowing blowing Sources of Sound: Vibrating Strings and Air Columns The 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 Waves The 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 Waves Phy 2054 Lecture Notes 12

  27. Standing Waves First Harmonic - Fundamental Second Harmonic Third Harmonic Phy 2054 Lecture Notes 12

  28. Chapter 14 Sound 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.

  29. Standing Waves in Air Columns L First Harmonic - Fundamental Second Harmonic Third Harmonic A tube open at both ends has displacement antinodes, at the ends. Phy 2054 Lecture Notes 12

  30. Chapter 14 Sound 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

  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 First Harmonic - Fundamental L Third Harmonic Fifth Harmonic A tube closed at one end has a displacement node at the closed end. Phy 2054 Lecture Notes 12

  33. Chapter 14 Sound 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) 760 Hz (D) 1050 Hz

  34. Standing Waves in Air Columns

  35. Beats Beat Frequency

  36. Chapter 12 Sound 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.

  37. Chapter 12 Sound 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.

  38. END

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