# Tagged Questions

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### Propagation/generation of sound is an isentropic process

Is the propagation and generation of sound an isentropic process? Is it because it is a reversible adiabatic process? Why would it be adiabatic? Does it happen so fast that there is no time to ...
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### Why sound does not heat up the air?

Both thermal energy and air are propagated through vibration of particles so why sound does not heat up the air e.g loud musical instrument does not generate much heat ?
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### Difference between sound and heat at particle level

If heat (or thermal energy) are vibrations of particles and sound is a wave that is propagated through medium e.g vibration of air particles, what indicates if vibration of particles will be perceived ...
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### SInce heat is a vibration in solids, isn't it just small scale sound? [duplicate]

On an atomic scale I think of electrons hitting positive ions in an electric lattice. Most energy there is heat energy. If I think of ball bearings flying through a large lattice, I think sound is ...
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### What is the minimum pressure of a medium for which a sound wave can exist?

At what pressure will be particles in a medium be unable to form a sound wave when disturbed? How can this pressure be described mathematically? My guess is that this would correspond to the point at ...
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### Speed of Sound?

The speed of sound in a gas may be given by the following formula, $$c = (kRT)^{1/2},$$ where $k$ is specific heat ratio, $R$ is the gas constant and $T$ is the temperature. What are the limits of ...
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### Why does a cooling motorcycle make popping noises?

I was sitting in my parked car tonight when a Harley-Davidson motorcycle parked next to me. With my window down, I could hear that as the motorcycle was cooling down, it was giving off some type of ...
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### Rijke tube: Why Sound is maximum when heated 1/4th length from bottom of tube

Why is it that the maximum sound coming from a Rijke tube happens only when heated wire gauze is placed at 1/4th the length of the tube from the bottom. According to Rayleigh: If heat be ...
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### Simple explanation of relation between speed of sound and r.m.s. speed?

In an ideal gas, the speed of sound $v_s$ is related to the r.m.s. molecular speed $v_m$ by $$\frac{v_s}{v_m}=\sqrt{\frac{\gamma}{3}} \qquad ,$$ where $\gamma=C_p/C_v=7/5$ for a diatomic gas. I ...
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### Heating coffee by yelling?

Is it a myth that yelling to a coffee mug will heat it? I have been hearing my friend saying that screaming will heat coffee or water.
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### Thermal Penetration Depth discrepancy

I've been working on a project that involves thermoacoustics, and one of the commonly-used values in this field is know as the thermal penetration depth. It is calculated as follows: \delta_k = ...
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### What arrangement of sound waves would be needed to heat air in a typical sized room?

From what I understand, sound is simply the jostling of the molecules that make up the air in a specific pattern, widely known as waves. I also know that these are longitudinal waves. If we were to ...
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### Why does thermal resistance go down as temperature goes up?

Here is the thermal resistance data for three speaker coils disengaged from the speaker cone. Any ideas? I would think it would be a horizontal line. http://en.wikipedia.org/wiki/Thermal_resistance ...