What is Speed of sound: Definition and 271 Discussions

The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At 20 °C (68 °F), the speed of sound in air is about 343 metres per second (1,235 km/h; 1,125 ft/s; 767 mph; 667 kn), or a kilometre in 2.9 s or a mile in 4.7 s. It depends strongly on temperature as well as the medium through which a sound wave is propagating. At 0°C/32°F, the speed-of-sound is 1192 km/h, 741 mph.The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior.
In colloquial speech, speed of sound refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids. For example, while sound travels at 343 m/s in air, it travels at 1,481 m/s in water (almost 4.3 times faster) and at 5,120 m/s in iron (almost 15 times faster). In an exceptionally stiff material such as diamond, sound travels at 12,000 metres per second (39,000 ft/s),— about 35 times its speed in air and about the fastest it can travel under normal conditions.
Sound waves in solids are composed of compression waves (just as in gases and liquids), and a different type of sound wave called a shear wave, which occurs only in solids. Shear waves in solids usually travel at different speeds, as exhibited in seismology. The speed of compression waves in solids is determined by the medium's compressibility, shear modulus and density. The speed of shear waves is determined only by the solid material's shear modulus and density.
In fluid dynamics, the speed of sound in a fluid medium (gas or liquid) is used as a relative measure for the speed of an object moving through the medium. The ratio of the speed of an object to the speed of sound in the fluid is called the object's Mach number. Objects moving at speeds greater than Mach1 are said to be traveling at supersonic speeds.

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  1. Dante Meira

    B Speed of sound in steel at different temperatures?

    Is there a formula to calculate the speed of propagation of sound waves through steel (a steel bar, for example) according to the temperature of steel?
  2. S

    I How fast does a blastwave travel?

    I read on Wikipedia , Encyclopedia Britannica and threads on this forum that shockwaves travel faster than the speed of sound, but when I watched this youTube video, it appears that even a shockwave from a C4 detonation travels at about the speed of sound. I have extracted a couple of frames...
  3. K

    Measuring the Speed of Sound in Water, Using Faraday's Law

    Hi! This project involves both mechanical and electrical elements, so I'm discussing it in this forum since I'm not sure which one it would fit better into. I'm working on an experiment in which I'm trying to measure the speed of sound through water. The approach is simple: I have a long...
  4. C

    Speed of sound from resonant length of tube vs tuning fork wavelengths

    The graph is, I do not understand why how it is possible to find the speed of sound from the gradient for this graph. Can someone please help? Many thanks!
  5. fascinated

    Why is the speed of sound used here? And is this correct?

    If two people are holding a stick going from the Earth to the moon and the one on Earth pulls the stick, would the person on the moon feel it immediately? This question was answered on Quora and the answer given involves the speed of sound and claims that the person on the moon would not feel...
  6. R

    Variation of the Speed of Sound in metals under tension

    In a block of metal, each metal has a characteristic speed of sound. When metal is under tension, such as a guitar string, the speed rises as the tension increases. How does the speed vary (in a block say) as a function of tension along each of the three axes? I am assuming that transverse...
  7. snoopies622

    Confusion about the derivation of the speed of sound

    I've having trouble understanding a derivation of the speed of sound waves, which is actually similar to another derivation I found a couple days ago. Let's suppose the sound is moving through water in a long cylindrical horizontal pipe. The premises of the derivation are 1.) For a given...
  8. E

    Speed of sound in a relativistic fluid

    Let us consider the co-moving observer ##\mathscr{C}## for whom ##E = \epsilon## and ##\mathbf{\vec{V}} = \mathbf{\vec{0}}##. Doing the perturbation stuff to the first of the relevant equations gives$$\partial_t \delta \epsilon + \boldsymbol{\nabla} \cdot ([\epsilon + p] \delta \mathbf{\vec{V}})...
  9. L

    Uncertainty of Speed of Sound in water, using Mackenzie's Equation

    I need to calculate the overall uncertainty of the value I have obtained for the speed of sound in water, using Mackenzies equation... I am not sure in what way to combine the above uncertainties. Any help would be greatly appreciated! Lloyd
  10. T

    I Speed of Sound & Light: Is it True?

    Are the following statements true? --------------------------------------------------------------- If a speaker and a listener are stationary with respect to the air, a listener will measure the speed of sound at about 343 m/s. Since the speed of a sound wave in air is dependent only on the...
  11. G

    B Speed of Light & Sound: Revolutionary Phenomenon?

    If sound (or any wave) was transmitted in a medium whose density was vanishingly low , would that wave propagate in the same way as em radiation in a vacuum? And vice versa does em radiation propagate in the same way as ,say sound so long as it is in a dense enough medium? In other words...
  12. J

    The hot chocolate effect to investigate the effects on speed of sound

    Summary:: The Hot chocolate effect is an investigation that extracts the essence about the effects on speed of sound. This is carried out in this sequence: A cup filled with liquid is continiously being tapped from the bottom. Meanwhile, a disturbance in the longitudinal sound waves is being...
  13. B

    Speed of sound related to absolute temperature

    Here is the Q Very unsure about how to approach this question but this is what I have tried Any help would be really appreciated! Thanks
  14. greg_rack

    Speed of sound in an ideal gas

    First of all I thought it was necessary to calculate the temperature(the only data missing for the formula) using the ideal gas equation(since I've already been given 'p' and 'V'), and plug it in the 'v' formula, but the problem immediately occurred when i tried to find out the number of...
  15. Harini Krishna

    Calculating the speed of sound in water

    Hi,i want to calculate the speed of sound in water Containing Chlorine : 4mg/L in 1L distill Water Chloroamine : 4mg/L in 1L distill Water Florides : 0.5mg/L + in 1L distill Water Copper : 0.005mg/L + in 1L distill Water Lead : 1.3 mg/L in 1L distill Water Can you please help in...
  16. anonymous99

    Does the speed of sound depend on the speed of the medium?

    This means the sound wave reaches the outlet faster as it travels in the same direction as the medium. But I was reading online that speed of sound is independent of the medium so I don't know why my professor used this approach. If speed of sound was dependent on the medium, then wouldn't shock...
  17. T

    Adiabatic approximation in the derivation of the speed of sound

    The speed of sound in a gas at temperature T is given to be ## v=\sqrt{\frac{\gamma RT}{M}}##, where ##\gamma## is the adiabatic exponent, R is the gas constant and M is the molar mass of the gas. In deriving this expression, we assumed that the compression and expansion processes were so fast...
  18. K

    Dimensional analysis (Speed of sound)

    I've been going round in circle and am stuggling as maths is not my strong suit. Any ideas? Up to the point where i equate the powers and then confuse myself, any help would be greatly appreciated.
  19. Creed

    Finding out the speed of sound

    d² = 40² + 60² ---> I 60 = V.t ---> II 40 + d = V.(t + 1/8) ---> III Thanks in the advance. :)
  20. D

    Why does a higher density slow down sound in air?

    Homework Statement Sorry, it's not an actual problem, it's just a statement I don't understand from my text - "The density of water vapor is less than that of dry air. Therefore, the higher the humidity (that is, the more water vapor there is in the air), the lower the density of the air. For...
  21. V

    Does the speed of sound change in metal when heated?

    Is the speed of sound different through the same piece of metal when it is heated compared to when at ambient temperature?
  22. F

    I Variations in the speed of sound in a star

    I try to understand the following graphics with x-axis being the radius of a typical star : I would like to knwo if ##\delta c/c## (y-axis) represents the relative error between theoretical and experimental values or if it represents the fluctuations of speed of sound inside. If these are...
  23. T

    Speed of sound in steel vs air

    I saw on a web page a video of tiny Agnes Scott College vs Princeton University from 1966 on GE College Bowl.Agnes Scott won (!), but one of the questions that both schools got wrong was asked by the moderator: The speed of sound in air is about 1,100 feet/sec. The speed of sound in steel is...
  24. Dr. Courtney

    Direct Echo-Based Measurement of the Speed of Sound - Comments

    Greg Bernhardt submitted a new PF Insights post Direct Echo-Based Measurement of the Speed of Sound Continue reading the Original PF Insights Post.
  25. V

    Speed of Sound Experiment: Hear the Results

    Imagine a car which has a speaker attached to the back. Speaker is blasting very high volume music towards the reverse direction of the car. Now the car starts accelerating and in a few seconds starts moving faster than the speed of sound. Will a listener be able to hear the sound now. Will...
  26. P

    A Measuring Viscosity via the Speed of Sound

    Hello, I am on the search for papers, books, etc. on how one can measure the viscosity of viscous materials via the speed of sound. I've searched for a while now and haven't been able to find much on this topic. Any help is greatly appreciated.
  27. S

    Can the Speed of Sound Be Measured Using Frequency and Time Delay Data?

    Suppose we have an ultrasonic transmitter and an ultrasonic receiver, separated by some fixed distance ##d##. Both devices are attached to an oscilloscope. The transmitter generates ultrasonic waves at some frequency ##f## that we can change. The receiver is some piezoelectric that translates...
  28. P

    Speed of sound: viscosity dependece in liquids and solids

    Hello, Wikipedia gave me prior hints as to how the speed of sound depends on viscosity but after searching on Google scholar and Google, I have yet to find any direct equations/findings that give a direct relationship of the speed of sound to the visocisty of fluids and solids outside of...
  29. B

    Measuring the speed of sound in an iron tube

    For physical experiment I have a project in which I have to measure the speed of sound in the air. 1. If I take an iron tube (inside is air) and a speaker, 2. put the speaker at the beginning of a tube, 3. speaker is connected to frequency generator (with which I can change frequencies)...
  30. Superfluid universe

    I How is this formula for the speed of sound derived?

    c² = (n/m) ∂²U/∂n² where U = vacuum energy density as a function of the quasiparticle density n = quasiparticle number density m = bare mass of quasiparticle Is there a book, article where this formula is explained? Thank you.
  31. M

    Sources of Error in a Speed of Sound Experiment

    Homework Statement Determine sources of error which could have affected the results. Some background information: The lab consisted of playing a tone generated by a tone generator above a standing open-closed tube which had water in it. The first harmonic was measured through a computer system...
  32. F

    I Need to Calculate the Speed of Sound for a Lab

    Homework Statement Calculate the speed of sound in the classroom. You can use: Tuning forks, water, beaker, pvc pipe, ringstands, etc. Homework Equations v = f(wavelength) For fundamental frequency: L = 1/4(wavelength) For fundamental frequency: f = v/4L The Attempt at a Solution Here is...
  33. S

    I What is the propagation speed of a diffusion

    Hello everybody! For my water in nanoscaled-pores simulations with SPH I need a value for the characteristic velocity. My planned approach is to estimate this value by attaining the propagation speed of a diffusion wave. But I have problems with understanding this process since I find some...
  34. C

    Measuring the Speed of Sound: Examining the Frequency of Clicks

    Homework Statement This is a problem from the Cambridge Natural Science Admissions Assesment. A student carries out an experiment to measure the speed of sound. A loudspeaker that emits sound in all directions is placed between two buildings that are 128 m apart as shown. The student and...
  35. K

    Speed of sound in steel dependance on temperature

    Hello, Nice easy question for you all today: I would like to know how the speed of sound in steel varies with temperature. A google search didnt reveal a great deal, so if a physicist could confirm the relationship, that would be much appreciated. I know that: v = √shear modulus/density...
  36. M

    Solids with different sound velocity at diffrent tempratures

    i work on phononic crystals and i want to find solids with diffrent sound velocities and mass density in diffrent temprature i can just find BST but i need more matherials please help me my friends best regards
  37. Y

    Can the speed of sound in air be faster?

    Sound is vibration of air molecules knocking into each other. Intuitively, it seems the faster a molecule travels before hitting another, the faster the propagation of sound. Can't you hit air molecules harder, so the air molecules will travel faster and spend less time between collisions, and...
  38. baldbrain

    Speed of Sound using a Resonant tube

    Homework Statement In the experiment for the determination of the speed of sound using a resonance tube, the diameter of the column tube is 4 cm. The frequency of the tuning fork is 512 Hz. The air temperature is 38° C in which the speed of sound is 336 m/s. The zero of the meter scale...
  39. lightofthemoon

    What is the Speed of Sound in this Lab Setup?

    Homework Statement In this part of the lab you tracked a single peak as you moved a microphone in order to get a good value of the speed of sound. This question will lead you through a similar process with just two measurements. (The lab set up: speaker emitting the signal faced one microphone...
  40. T

    How long does it take for sound to travel 1 mile at a speed of 740 mph?

    Let's assume a speed of sound of approximately 740 mph at sea level. If I there are two aircraft traveling in formation 1 mile apart (one in front of the other) at 730 miles per hour, how long will it take for the sound of single gunshot fired from the trailing aircraft to reach the lead...
  41. Surya97

    Why is there a set speed of sound in a certain medium?

    Why does sound always move at the local speed of sound in a medium (in other words, why is there a set speed of sound for certain medium)? I understand that sound is a compression wave, but shouldn't a louder sound (i.e. one with a higher amplitude) move faster? What about a higher pitch noise...
  42. F

    What is the speed of sound from a fast-approaching train?

    Someone once said, there are no stupid questions, just stupid people. All the questions I have read about sound coming from an approaching object only seem to deal with the frequency of sound, not its speed. So with that in mind, I have the following (hopefully non-stupid) question: A train is...
  43. N

    Kinematics/speed of sound question

    Homework Statement A stone is dropped in a well. The splash is heard 3s later. What is the depth of the well? Homework Equations constant acceleration equations take speed of sound to be 343 m/s. The Attempt at a Solution For the stone: u = 0 a = g s = ut + 0.5at^2 subbing it all in you get...
  44. F

    I A light wave and a sound wave travelling together

    If we could imagine a medium that could slow down light quite significantly, if a sound wave and a light wave were both passing through this medium, would the sound wave see the light wave passing by at the speed that light passes through that medium or would it see it passing by at the speed...
  45. F

    I Speed of light and speed of sound both constant

    I believe that the speed of sound is constant in the same medium as is the speed of light. I would like to understand why we need the the theory of relativity to explain the speed of light being constant but I believe it is not used to explain why the speed of sound is constant within the same...
  46. G

    Sound in a gas of non-interacting particles?

    Hi. In some statistical approaches (e.g. canonical ensemble), the particles of an ideal gas are non-interacting. Still, it's possible to derive the ideal gas law and other thermodynamic relations. Wikipedia gives an equation for the speed of sound in an ideal gas. How can there be waves in a...
  47. C

    Confusion regarding the speed of sound in wind

    One of my students asked me the seemingly innocuous question of "how does wind affect the speed of sound?". My immediate thought was that the velocity of the wave would be the vector sum of the velocity of the wind and the velocity of sound waves in still air. However, upon further reflection I...
  48. Erenjaeger

    Please help, stuck -- Standard error in speed of sound wave....

    https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-xfa1/v/t34.0-12/13100972_1004336679646107_71786442_n.png?oh=c0e0ad9cf30125d301d2069c6402b621&oe=57222F24&__gda__=1461854936_dad2ac5d3bd3a844b9428cd47c7dc733 Not sure if this counts as "advanced physics homework" but can someone please help me...
  49. B

    How to graph a linear relationship between T and v of sound?

    Homework Statement I did an experiment involving the speed of sound at different temperatures. I placed two microphones at a fixed distance apart and I measured the time taken for a sound wave to travel between the two mics. I repeated this for different temperatures. I want to make a graph for...