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slorraine

Describe how sound waves move through different types of matter. Compare the speed at which sound moves through solids, liquids, and gases and explain why sound travels differently through different types of matter?

  • one year ago
  • one year ago

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  1. imron07
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    http://en.wikipedia.org/wiki/Sound_wave#Longitudinal_and_transverse_waves

    • one year ago
  2. JamesWolf
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    SUMMARY:- How does sound move? Longitudinal and transverse waves Speed of sound through phases? Fastest in solid, then liquid, then gas Why? Density Sound moves in either transverse or longitudinal waves by collisions of adjacent particles . All phases of matter, can propagate sound in longitudinal waves but only solids transfer sound transversely. Longitudinal waves act parallel to the direction of travel, transverse acts at a right angle. |dw:1349707697146:dw| |dw:1349707906151:dw| Imagine for both images you are looking side on watching the wave travel past. In the first image, longitudinal waves, the initial vector starting the wave points in the same direction as that which the wave travels in. In the second image the starting vector has two non zero components, one in the direction of travel, and one parallel to this. The speed of sound, v_s, is given by the equation\[v_{s}= \sqrt{\frac{ B }{ p }}\] where B is the bulk modulus or stiffness (how pressure changes as you change volumes) and p is density. So since B is on the top, the speed of sound increases with more stiffness, and increases with less density (because p is on the bottom). Phases of matter in order of increasing stiffness (increasing speed): \[Gas \rightarrow Liquid \rightarrow Solid\]Phases of matter in order of decreasing density (increasing speed): \[Solid \rightarrow Liquid \rightarrow Gas\] So if your a medium propagating sound waves whats it more important to have? low density or high stiffness? Well it seems to turn out that density is the thing which really matters. In a gas the molecules are SO spread out that it takes ages between each collision. so the speed is generally slower. Think of it like a pool table with spread out balls, each ball has to travel a certain distance before it can pass on its kinetic energy to the next ball. Since temperature is a measure of kinetic energy, increasing the temperature will also have an effect on speed. This is most apparant in a gas. In a liquid the molecules are more tightly packed (higher density) so travel faster than a gas (over 4 times faster in water than air) Interestingly since liquid is denser, the individual particles carrying the wave have less chance of flying off in a direction thatthe wave isn't traveling in, this is why sound travels further in liquid. Lucky whales. For this I imagine an ice machine that spews ice onto the floor. With few ice coming out per second (gas) there is less chance of a collision between the pieces of ice, and the overall energy is low. However with a liquid, there is loads of ice! constantly bumping into each other, creating a hell of a mess. In a solid the lattice of particles are packed very tightly, so as you expect sound travels extremely fast through them. Here it is best to imagine newtons cradle, when one side is dropped the energy is passed almost instantaneously. Newtons cradle is an example of a longitudinal wave in a solid.|dw:1349708262176:dw|

    • one year ago
  3. slorraine
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    Wow thank you! @JamesWolf

    • one year ago
  4. JamesWolf
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    no problem, sorry about the terrible drawings

    • one year ago
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