7: Property of Sound, Doppler Effect, and Interferences
- Page ID
- 121970
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 7.1: Introduction and Learning Objectives
- This page outlines the fundamentals of sound, covering its properties, propagation, interference, the Doppler Effect, and sound intensity, emphasizing their applications in fields like radar and medical ultrasound. It also stresses effective teaching methodologies for K-12 educators, promoting student engagement through demonstrations and multimedia tools.
- 7.2: Prelude to Sound
- Sound is an example of a mechanical wave, specifically, a pressure wave: Sound waves travel through the air and other media as oscillations of molecules. Normal human hearing encompasses an impressive range of frequencies from 20 Hz to 20 kHz. Sounds below 20 Hz are called infrasound, whereas those above 20 kHz are called ultrasound. Some animals, like bats, can hear sounds in the ultrasonic range.
- 7.3: Sound Waves
- This page explains that sound is the transfer of energy through waves from vibrating objects, creating longitudinal waves that move through matter. It emphasizes that sound exists independently of a listener and cannot travel through empty space. Historical experiments, particularly those conducted by Robert Boyle, demonstrate that sound needs a medium for transmission, with different materials affecting sound quality uniquely.
- 7.4: Speed of Sound
- This page discusses the speed of sound, which averages 343 m/s in air at 20°C, varying by medium with solids being fastest. Temperature influences speed; it decreases in cooler conditions (e.g., 331 m/s at 0°C, 319 m/s at -20°C). Grasping these concepts is valuable for practical applications such as storm tracking.
- 7.5: Intensity and Loudness of Sound
- This page explains loudness as the perception of sound intensity, measured in decibels (dB). It notes that higher decibel levels correspond to louder sounds, with a 10-dB increase making sound ten times louder. Loudness is affected by sound wave amplitude and distance from the source, which diminishes intensity over distance. It also highlights the potential hearing damage from exposure to high decibel levels.
- 7.6: Frequency and Pitch of Sound
- This page explains pitch, which is the perception of sound frequency. High frequencies result in high-pitched sounds, while low frequencies correspond to low-pitched sounds. Frequencies below 20 Hz are infrasound and above 20,000 Hz are ultrasound, both inaudible to humans. Some animals, like dogs and bats, can hear ultrasound. Bats utilize it for navigation by emitting sound waves that bounce off objects, enabling them to navigate in darkness.
- 7.7: Doppler Effect and Sonic Booms
- The Doppler effect is an alteration in the observed frequency of a sound due to motion of either the source or the observer. The actual change in frequency is called the Doppler shift. A sonic boom is constructive interference of sound created by an object moving faster than sound. A sonic boom is a type of bow wake created when any wave source moves faster than the wave propagation speed.
- 7.8: Ultrasound
- This page discusses ultrasound, which encompasses sound waves above 20,000 Hz that humans cannot detect. It highlights how bats and dolphins use echolocation with ultrasound for navigation and how sonar employs similar principles to locate underwater objects. Additionally, it covers ultrasonography, a medical imaging technique using harmless ultrasound waves for internal diagnostics. Overall, the page emphasizes the varied applications of ultrasound in nature and technology.
- 7.9: End of Chapter Activity
- This page describes a lesson plan for 12th graders on sound properties, the Doppler effect, and interference, utilizing AI tools and Bloom's Taxonomy. It includes definitions, explanations, hands-on labs, and projects that promote experimentation and reflection. Daily objectives feature activities like observing the Doppler effect and wave interference experiments, culminating in a digital presentation to foster comprehensive understanding and engagement with advanced concepts in sound.
- 7.10: End of Chapter Key Terms
- This page defines key properties of sound as energy transmitted through vibrating waves across different mediums. It explores concepts like speed, waves, loudness, intensity, decibels, amplitude, frequency, pitch, and wavelength. Additionally, it discusses ultrasound, infrasound, the Doppler Effect, and applications such as animal echolocation and sonar technology.