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Q & A: sound in glass

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Most recent answer: 10/22/2007
what is the sound accelaration via glass
- Winner (age 9)
Mulia Bhakti, Makassar, Indonesia
I'm not sure exactly what effect you are referring to, but I'll guess that it is that sound travels faster in most glass than in air. The speed of sound is different in different materials. The stiffer a material is, the faster sound travels in it. The denser it is, the slower sound travels in it. Typical glass material is much denser than air, but also much stiffer, since air is easily compressed. For air the sound speed is about 330 m/s under ordinary conditions. Most typical glass materials end up with sound speeds of 2000 m/s to 6000 m/s, depending both on the type of glass and the type of sound. There's nothing special about glass here- most typical solids have similar sound speeds.
Incidentally, in solids there are two types of sound (longitudinal and transverse) which travel at different speeds. Longitudinal waves consist of layers of more or less compressed material, alternating along the direction the wave travels. That's the only type of sound in a gas. Transverse sound (generally faster) consists of back-and-forth displacements at right angles to the direction the sound wave travels- just like a wave on a violin string.


(published on 10/22/2007)

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