Technology & Engineering
Speed of Sound
The speed of sound refers to the rate at which sound waves travel through a medium, such as air, water, or solid materials. It is influenced by the density and elasticity of the medium. In air at room temperature, the speed of sound is approximately 343 meters per second (1235 kilometers per hour).
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12 Key excerpts on "Speed of Sound"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 5 Speed of Sound The Speed of Sound is the distance traveled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the Speed of Sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds. In fluid dynamics, the Speed of Sound in a fluid medium (gas or liquid) is used as a relative measure of speed itself. The speed (in distance per time) divided by the Speed of Sound in the fluid is called the Mach number. Objects moving at speeds greater than Mach1 are said to be traveling at supersonic speeds. The Speed of Sound in ideal gases is independent of frequency, but it weakly depends on frequency for all real physical situations. It is a function of the square root of temperature, but is nearly independent of pressure or density for a given gas. For different gases, the Speed of Sound is inversely dependent on square root of the mean molecular weight of the gas, and affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is a type of compression. Although, in the case of gases only, the Speed of Sound may be expressed in terms of a ratio of both density and pressure, these quantities are not fully independent of each other, and canceling their common contributions from physical conditions, leads to a velocity expression using the independent variables of temperature, composition, and heat capacity noted above. In common everyday speech, Speed of Sound refers to the Speed of Sound waves in air. However, the Speed of Sound varies from substance to substance. Sound travels faster in liquids and non-porous solids than it does in air.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 6 Speed of Sound The Speed of Sound is the distance traveled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the Speed of Sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds. In fluid dynamics, the Speed of Sound in a fluid medium (gas or liquid) is used as a relative measure of speed itself. The speed (in distance per time) divided by the Speed of Sound in the fluid is called the Mach number. Objects moving at speeds greater than Mach1 are said to be traveling at supersonic speeds. The Speed of Sound in ideal gases is independent of frequency, but it weakly depends on frequency for all real physical situations. It is a function of the square root of temperature, but is nearly independent of pressure or density for a given gas. For different gases, the Speed of Sound is inversely dependent on square root of the mean molecular weight of the gas, and affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is a type of compression. Although, in the case of gases only, the Speed of Sound may be expressed in terms of a ratio of both density and pressure, these quantities are not fully independent of each other, and canceling their common contributions from physical conditions, leads to a velocity expression using the independent variables of temperature, composition, and heat capacity noted above. In common everyday speech, Speed of Sound refers to the Speed of Sound waves in air. However, the Speed of Sound varies from substance to substance. Sound travels faster in liquids and non-porous solids than it does in air.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter-2 Speed of Sound Pressure-pulse or compression-type wave (longitudinal wave) confined to a plane. This is the only type of sound wave that travels in fluids (gases and liquids) Transverse wave affecting atoms initially confined to a plane. This additional type of sound wave (additional type of elastic wave) travels only in solids, and the sideways shearing motion may take place in any direction at right angles to the direction of wave- ________________________ WORLD TECHNOLOGIES ________________________ travel (only one shear direction is shown here, at right angles to the plane). Furthermore, the right-angle shear direction may change over time and distance, resulting in different types of polarization of shear-waves The Speed of Sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the Speed of Sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds. In fluid dynamics, the Speed of Sound in a fluid medium (gas or liquid) is used as a relative measure of speed itself. The speed (in distance per time) divided by the Speed of Sound in the fluid is called the Mach number. Objects moving at speeds greater than Mach1 are traveling at supersonic speeds. The Speed of Sound in an ideal gas is independent of frequency, but it weakly depends on frequency for all real physical situations. It is a function of the square root of temperature, but is nearly independent of pressure or density for a given gas. For different gases, the Speed of Sound is inversely dependent on square root of the mean molecular weight of the gas, and affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is a type of compression.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter-2 Speed of Sound Pressure-pulse or compression-type wave (longitudinal wave) confined to a plane. This is the only type of sound wave that travels in fluids (gases and liquids) Transverse wave affecting atoms initially confined to a plane. This additional type of sound wave (additional type of elastic wave) travels only in solids, and the sideways shearing motion may take place in any direction at right angles to the direction of wave-travel (only one shear direction is shown here, at right angles to the plane). Furthermore, ____________________ WORLD TECHNOLOGIES ____________________ the right-angle shear direction may change over time and distance, resulting in different types of polarization of shear-waves The Speed of Sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the Speed of Sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds. In fluid dynamics, the Speed of Sound in a fluid medium (gas or liquid) is used as a relative measure of speed itself. The speed (in distance per time) divided by the Speed of Sound in the fluid is called the Mach number. Objects moving at speeds greater than Mach1 are traveling at supersonic speeds. The Speed of Sound in an ideal gas is independent of frequency, but it weakly depends on frequency for all real physical situations. It is a function of the square root of temperature, but is nearly independent of pressure or density for a given gas. For different gases, the Speed of Sound is inversely dependent on square root of the mean molecular weight of the gas, and affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is a type of compression.
- (Author)
- 2001(Publication Date)
- Academic Press(Publisher)
7. Speed of Sound AS A THERMODYNAMIC PROPERTY OF FLUIDS Daniel G. Friend Physical and Chemical Properties Division Chemical Science and Technology Laboratory National Institute of Standards and Technology Boulder, Colorado Abstract In this Chapter, we review the principles of sound propagation in fluid systems. From a study of the hydrodynamic equations, sound propagation is shown to be a wave phenomenon. The Speed of Sound then can be derived at any state point from a knowledge of the thermodynamic surface of the fluid of interest. Several model equations of state are reviewed, and it is shown how the Speed of Sound can be obtained for a variety of systems. We then focus on several fluids of particular interest, and show the behavior of the sound speed over a wide range of the temperature and pressure variables. Tabulated values of the Speed of Sound are given for argon, nitrogen, water, and air based on the current standard reference thermodynamic surfaces. 7.1 Introduction In this Chapter, we discuss the propagation of sound in fluids and provide information about the thermodynamic Speed of Sound over substantial ranges of the state variables for a variety of fluids. In the context of this chapter, we consider sound to arise from a small periodic and isentropic (constant entropy) perturbation of the local equilibrium in a fluid, which, as we shall see, gives rise to a standard wave equation. The systems under consideration include both pure fluids and mixtures in the liquid, vapor, and supercritical states. Thus the range in temperature is from the melting line to very high temperatures (a dissociation limit), and the range in pressure is from very low values (below which the continuum approximation would not be valid) to the solidification locus (at least in principle).
- David Halliday, Jearl Walker, Patrick Keleher, Paul Lasky, John Long, Judith Dawes, Julius Orwa, Ajay Mahato, Peter Huf, Warren Stannard, Amanda Edgar, Liam Lyons, Dipesh Bhattarai(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
CHAPTER 17 Waves — II 17.1 Speed of Sound LEARNING OBJECTIVES After reading this module, you should be able to: 17.1.1 distinguish between a longitudinal wave and a transverse wave 17.1.2 explain wavefronts and rays 17.1.3 apply the relationship between the Speed of Sound through a material, the material’s bulk modulus, and the material’s density 17.1.4 apply the relationship between the Speed of Sound, the distance travelled by a sound wave, and the time required to travel that distance. KEY IDEAS • Sound waves are longitudinal mechanical waves that can travel through solids, liquids, or gases. The speed v of a sound wave in a medium having bulk modulus B and density is v = √ B . In air at 20°C, the Speed of Sound is 343 m/s. • The bulk modulus relates the fractional volume change ΔV /V to the pressure change Δp causing it: B = − Δp ΔV∕V . Why study physics? As the wind blows at Emu Park in Queensland, you can savour the melodious harmonies, resulting from the standing waves, produced in the open pipes of the Singing Ship monument, to commemorate Captain Cook sailing by the Keppel Coast in 1770. In New Zealand, the cores of conifer logs often have relatively low stiffness and high instability during the drying phase. Forestry researchers have measured the Speed of Sound in logs to analyse these issues, to establish techniques and growth conditions in order to minimise this problem. 1 To begin our discussion of the physics of sound, we must first answer the question, ‘What are sound waves?’ Sound waves As we saw in chapter 16, mechanical waves are waves that require a material medium to exist. There are two types of mechanical waves: transverse waves involve oscillations perpendicular to the direction of wave travel; longitudinal waves involve oscillations parallel to the direction of wave travel. Pdf_Folio:342 FIGURE 17.1 A sound wave travels from a point source S through a three-dimensional medium.
- David Halliday, Robert Resnick, Jearl Walker(Authors)
- 2023(Publication Date)
- Wiley(Publisher)
C H A P T E R 17 After reading this module, you should be able to . . . 17.1.1 Distinguish between a longitudinal wave and a transverse wave. 17.1.2 Explain wavefronts and rays. 17.1.3 Apply the relationship between the Speed of Sound through a material, the material’s bulk modulus, and the material’s density. 17.1.4 Apply the relationship between the Speed of Sound, the distance traveled by a sound wave, and the time required to travel that distance. 17.1 Speed of Sound LEARNING OBJECTIVES 473 KEY IDEA 1. Sound waves are longitudinal mechanical waves that can travel through solids, liquids, or gases. The speed v of a sound wave in a medium having bulk mod- ulus B and density ρ is v = √ __ B __ ρ (Speed of Sound). In air at 20°C, the Speed of Sound is 343 m/s. What Is Physics? The physics of sound waves is the basis of countless studies in the research journals of many fields. Here are just a few examples. Some physiologists are concerned with how speech is produced, how speech impairment might be corrected, how hearing loss can be alleviated, and even how snoring is produced. Some acoustic engineers are concerned with improving the acoustics of cathedrals and concert halls, with reducing noise near freeways and road construction, and with repro- ducing music by speaker systems. Some aviation engineers are concerned with the shock waves produced by supersonic aircraft and the aircraft noise produced in communities near an airport. Some medical researchers are concerned with how noises produced by the heart and lungs can signal a medical problem in a patient. Some paleontologists are concerned with how a dinosaur’s fossil might reveal the dinosaur’s vocalizations. Some military engineers are concerned with how the sounds of sniper fire might allow a soldier to pinpoint the sniper’s location, and, on the gentler side, some biologists are concerned with how a cat purrs.
eBook - PDF- David Halliday, Robert Resnick, Jearl Walker(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
Waves—II 17.1 Speed of Sound Learning Objectives After reading this module, you should be able to . . . 17.1.1 Distinguish between a longitudinal wave and a transverse wave. 17.1.2 Explain wavefronts and rays. 17.1.3 Apply the relationship between the Speed of Sound through a material, the material’s bulk modulus, and the material’s density. 17.1.4 Apply the relationship between the Speed of Sound, the distance traveled by a sound wave, and the time required to travel that distance. Key Idea ● Sound waves are longitudinal mechanical waves that can travel through solids, liquids, or gases. The speed v of a sound wave in a medium having bulk modulus B and density ρ is v = √ __ B __ ρ (Speed of Sound). In air at 20°C, the Speed of Sound is 343 m/s. C H A P T E R 1 7 506 CHAPTER 17 WAVES—II In this book, a sound wave is defined roughly as any longitudinal wave. Seismic prospecting teams use such waves to probe Earth’s crust for oil. Ships carry sound-ranging gear (sonar) to detect underwater obstacles. Submarines use sound waves to stalk other submarines, largely by listening for the charac- teristic noises produced by the propulsion system. Figure 17.1.1 suggests how sound waves can be used to explore the soft tissues of an animal or human body. In this chapter we shall focus on sound waves that travel through the air and that are audible to people. Figure 17.1.2 illustrates several ideas that we shall use in our discussions. Point S represents a tiny sound source, called a point source, that emits sound waves in all directions. The wavefronts and rays indicate the direction of travel and the spread of the sound waves. Wavefronts are surfaces over which the oscillations due to the sound wave have the same value; such surfaces are rep- resented by whole or partial circles in a two-dimensional drawing for a point source. Rays are directed lines perpendicular to the wavefronts that indicate the direction of travel of the wavefronts.
eBook - PDFProceedings of the International Symposium on Two-Phase Systems
Progress in Heat and Mass Transfer
- G. Hetsroni, S. Sideman, J. P. Hartnett(Authors)
- 2017(Publication Date)
- Pergamon(Publisher)
As early as 1942 it was mentioned by Heinrich [1]. In recent years, consider-able effort has been focused on the problem of calculating the Speed of Sound in two-phase flow. In general the intent has been primarily to deduce the maximum flow rate under critical conditions rather than the speed at which its pressure waves would actually travel through mixture. Qualitatively, the phenomenon is reasonably easy to understand. Consider a mixture which is approximately 50% liquid and 50% vapor. If the mixture is homogeneous, the specific volume will be (within a factor of 2) that of the liquid—very low—while the com-pressibility (again within a factor of 2) will be roughly that of the vapor—very high. Since the Speed of Sound depends on the ratio of specific volume to compressibility, it will be quite low. In the case of single-component mixtures of liquid and vapor at saturation conditions, this already large effect can be dramatically enhanced by the extreme augmentation of t The authors are grateful for the support of this work by the National Science Foundation under grant N S F G K 1298, Office of Saline Water (Department of the Interior), under grant 14-01-0001-1165, and Whittaker Corp. which supported one of us (S. E. N . ) as a doctoral fellow for part of the time this work was in progress. 671 672 C. L. F E L D M A N , S. E. N Y D I C K A N D R. P. K O K E R N A K compressibility resulting from the vaporization and condensation that occurs with small pressure changes. As a first approximation to the Speed of Sound, it is useful to look at the isentropic Speed of Sound—that speed with which an infinitesimal wave would travel if the substance were at all times in thermodynamic equilibrium. This speed, expressed algebraically, is given in eqn. (1): id) s (2) This can be evaluated for two-phase mixtures and written in the form of eqn.
eBook - PDF- John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler(Authors)
- 2015(Publication Date)
- Wiley(Publisher)
STEP 2 Speed of Sound Since the air is assumed to be an ideal gas, the speed v of sound is related to the Kelvin temperature T and the average mass m of an air molecule by v 5 B g k T m (16.5) where g is the ratio of the specific heat capacity of air at constant pressure to that at constant volume (see Section 15.5), and k is Boltzmann’s constant. The temperature in this expression must be the Kelvin temperature of the air, which is related to its Celsius temperature T c by T 5 T c 1 273.15 (Equation 12.1). Thus, the Speed of Sound in air is v 5 B gk (T c 1 273.15) m This expression for v can be substituted into Equation 1, as shown on the right. x Figure 16.18 An ultrasonic ruler uses sound with a frequency greater than 20 kHz to measure the distance x to the wall. The blue arcs and blue arrow denote the outgoing sound wave, and the red arcs and red arrow denote the wave reflected from the wall. x 5 v( 1 2 t RT ) (1) ? x 5 v( 1 2 t RT ) (1) v 5 B gk (T c 1 273.15) m 16.6 | The Speed of Sound 433 Solution Combining the results of the modeling steps, we have STEP 1 STEP 2 x 5 v( 1 2 t RT ) 5 B gk (T c 1 273.15) m ( 1 2 t RT ) Since the average mass of an air molecule is given in atomic mass units (28.9 u), we must convert it to kilograms by using the conversion factor 1 u 5 1.6605 3 10 227 kg (see Section 14.1). Thus, m 5 (28.9 u)a 1.6605 3 10 227 kg 1 u b 5 4.80 3 10 226 kg The distance from the ultrasonic ruler to the wall is x 5 B gk(T c 1 273.15) m ( 1 2 t RT ) 5 B 7 5 (1.38 3 10 223 J/K)(32 °C 1 273.15) 4.80 3 10 22 kg [ 1 2 (20.0 3 10 23 s)] 5 3.50 m Related Homework: Problems 48, 50, 110 The physics of sonar. Sonar (sound navigation ranging) is a technique for determining water depth and locating underwater objects, such as reefs, submarines, and schools of fish. The core of a sonar unit consists of an ultrasonic transmitter and receiver mounted on the bottom of a ship.
eBook - PDF- John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler(Authors)
- 2018(Publication Date)
- Wiley(Publisher)
The Speed of Sound is an important parameter in the measurement of distance, as discussed for the ultrasonic ruler in Example 4. BIO THE PHYSICS OF . . . cataract surgery. Accurate distance measurements using ultrasonic sound also play an important role in medicine, where the sound often travels through liquid-like materials in the body. A routine preoperative procedure in cataract sur- gery, for example, uses an ultrasonic probe called an A-scan to measure the length of the eyeball in front of the lens, the thickness of the lens, and the length of the eyeball between the lens and the retina (see Figure 16.20). The measurement is similar to that discussed in Example 4 and relies on the fact that the Speed of Sound in the material in front of and behind the lens of the eye is 1532 m/s, whereas that within the lens is 1641 m/s. In cataract surgery, the cataractous lens is removed and often replaced with an implanted artificial lens. Data pro- vided by the A-scan facilitate the design of the lens implant (its size and the optical correction that it introduces). Solid Bars When sound travels through a long, slender, solid bar, the speed of the sound depends on the properties of the medium according to Long, slender, solid bar υ = √ Y ρ (16.7) where Y is Young’s modulus (defined in Section 10.7) and is the density. Reasoning At a distance of one mile from a storm, the observer in Figure 16.19 detects either type of wave only after a time that is equal to the distance divided by the speed at which the wave travels. This fact will guide our analysis. Answers (b) and (c) are incorrect. The rule involves the time that passes between seeing the lightning flash and hearing the thunder, not just the time at which either type of wave is detected. Therefore, both the speeds light and sound must play a role in the rule.
eBook - PDF- John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler(Authors)
- 2015(Publication Date)
- Wiley(Publisher)
STEP 2 Speed of Sound Since the air is assumed to be an ideal gas, the speed v of sound is related to the Kelvin temperature T and the average mass m of an air molecule by v 5 B g k T m (16.5) where g is the ratio of the specific heat capacity of air at constant pressure to that at constant volume (see Section 15.5), and k is Boltzmann’s constant. The temperature in this expression must be the Kelvin temperature of the air, which is related to its Celsius temperature T c by T 5 T c 1 273.15 (Equation 12.1). Thus, the Speed of Sound in air is v 5 B gk (T c 1 273.15) m This expression for v can be substituted into Equation 1, as shown on the right. x Figure 16.18 An ultrasonic ruler uses sound with a frequency greater than 20 kHz to measure the distance x to the wall. The blue arcs and blue arrow denote the outgoing sound wave, and the red arcs and red arrow denote the wave reflected from the wall. x 5 v( 1 2 t RT ) (1) ? x 5 v( 1 2 t RT ) (1) v 5 B gk (T c 1 273.15) m 16.6 | The Speed of Sound 385 Solution Combining the results of the modeling steps, we have STEP 1 STEP 2 x 5 v( 1 2 t RT ) 5 B gk (T c 1 273.15) m ( 1 2 t RT ) Since the average mass of an air molecule is given in atomic mass units (28.9 u), we must convert it to kilograms by using the conversion factor 1 u 5 1.6605 3 10 227 kg (see Section 14.1). Thus, m 5 (28.9 u)a 1.6605 3 10 227 kg 1 u b 5 4.80 3 10 226 kg The distance from the ultrasonic ruler to the wall is x 5 B gk(T c 1 273.15) m ( 1 2 t RT ) 5 B 7 5 (1.38 3 10 223 J/K)(32 °C 1 273.15) 4.80 3 10 22 kg [ 1 2 (20.0 3 10 23 s)] 5 3.50 m The physics of sonar. Sonar (sound navigation ranging) is a technique for determining water depth and locating underwater objects, such as reefs, submarines, and schools of fish. The core of a sonar unit consists of an ultrasonic transmitter and receiver mounted on the bottom of a ship.
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