Elastic modulus is the technical term. The phase of matter has a tremendous impact upon the elastic properties of the medium. In general, solids have the strongest interactions between particles, followed by liquids and then gases. For this reason, longitudinal sound waves travel faster in solids than they do in liquids than they do in gases. Even though the inertial factor may favor gases, the elastic factor has a greater influence on the speed v of a wave, thus yielding this general pattern:.
Inertial properties are those properties related to the material's tendency to be sluggish to changes in its state of motion. The density of a medium is an example of an inertial property. The greater the inertia i. As stated above, sound waves travel faster in solids than they do in liquids than they do in gases. However, within a single phase of matter, the inertial property of density tends to be the property that has a greatest impact upon the speed of sound.
A sound wave will travel faster in a less dense material than a more dense material. Thus, a sound wave will travel nearly three times faster in Helium than it will in air. This is mostly due to the lower mass of Helium particles as compared to air particles. The speed of a sound wave in air depends upon the properties of the air, mostly the temperature, and to a lesser degree, the humidity. Humidity is the result of water vapor being present in air.
Like any liquid, water has a tendency to evaporate. As it does, particles of gaseous water become mixed in the air. This additional matter will affect the mass density of the air an inertial property. The temperature will affect the strength of the particle interactions an elastic property. At normal atmospheric pressure, the temperature dependence of the speed of a sound wave through dry air is approximated by the following equation:.
Using this equation to determine the speed of a sound wave in air at a temperature of 20 degrees Celsius yields the following solution. The above equation relating the speed of a sound wave in air to the temperature provides reasonably accurate speed values for temperatures between 0 and Celsius. The equation itself does not have any theoretical basis; it is simply the result of inspecting temperature-speed data for this temperature range.
Other equations do exist that are based upon theoretical reasoning and provide accurate data for all temperatures. Nonetheless, the equation above will be sufficient for our use as introductory Physics students. For this reason, humans can observe a detectable time delay between the thunder and the lightning during a storm. Watch one of the air molecules. It takes one period for this molecule to move back and forth through a full cycle.
During this time, the wave shape has moved forward one complete wavelength. This is because the wave has to overlap with its initial shape after one period, because the molecule has to be back where it started after one period. Now, since speed is defined to be the distance per time, the speed of a sound wave has to be the wavelength of the wave divided by the period of the wave.
Since the wave is traveling forwards one wavelength per period, or since the frequency is defined to be one over the period, we can rewrite this formula as speed equals wavelength times frequency. This formula is accurate for all kinds of waves, not just sound waves, because a wave has to move one wavelength for every period.
Be careful. When looking at this equation, you might think that if you adjust the setting on your speaker and increase the frequency you'd also be increasing the speed of the sound wave, but that's not what happens.
If you increase the frequency, the wavelength will decrease by that same factor, and the speed of the sound wave will remain the same. In fact, there's nothing you can do to the speaker that would increase the speed of sound.
Related Stories. The proof-of-principle demonstration is analogous to looking directly into For each speaker, the scientists were able to Researchers propose the Rotons are an exception: their speed of sound changes significantly with the wavelength, it is also Foundational work here on optical-acoustic microchips opens door to low-heat, low-energy, fast A new study examines the propagation of energy A new study has now shown that both skills rely on The research was published in the journal Science Advances.
Source: Queen Mary University of London. LOG IN. Menu HOME. Search Query Submit Search. By Michael Irving. Facebook Twitter Flipboard LinkedIn. A new study has calculated the top speed of sound, which might occur in an exotic form of hydrogen.
View 1 Image. Michael Irving. Michael has always been fascinated by space, technology, dinosaurs, and the weirder mysteries of the universe. With a Bachelor of Arts in Professional Writing and several years experience under his belt, he joined New Atlas as a staff writer in
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