In this section,you will learn the relationship between transmission and sound and why there is difference according to the quality of medium.

  Trans mission medium and Sound

As we explained,longitodinal waves (such as sound waves)transmit not only through gaseous matters but also through liguid and solid matters.
Example of sound waves transmits through solid matter is yarn phone.Let's see how sound travels.
Yarn phone
You know what a yarn phone is,don't you?If you have two paper cups and yarn, you can make a telephone.How does the sound transmit from one cup to the other?
@The bottom of on cup vibrates.

AThe vibration travels through the yarn.

BThe vibration on the yarn cause the bottom of the other cup to vibrate.

This is the mechanism of a yarn phone.In this case,sound travels on the yarn,not through the air.A yarn phone is agood example of how sound transmits through solid matters.Why don't you look for other example of sound transmission through solid and liquid matters?

Then let's think about how fast or how slowly sound transmits through liquid,gasecus,and solid matters respectively.Please refer to the following chart.

※  ナツメ社 中村健太郎 著 「図解雑学 音のしくみ」

You may have heard that the speed of sound through the air is 340m/second.However,it is 331.5m/s when it is 0℃.At 14℃, it is 340m/s.
In the case of gaseous matters, the speed is less than 1000m/s whether in the air or helium or CO2.In the case of liquid matters,the speed of sound is around 1500m/s both in ditilled water and in seawater.In the case of solid matters, the speed is 3000m/s or above in ice and it is more than 5000m/s in glass and iron.So there is a large difference in the speed of sound depending on the material of the mediums-gaseous or liquid or solid.Why?Please look at the following chart.

※  ナツメ社 中村健太郎 著 「図解雑学 音のしくみ」

The dinsty and modulus of elasticity of the mediums are key factors for the speed of sound.Modulus of elasticity(unit is Pa)means the amount of pressure needed to deform the matter,that is,how hard the matter is.Density means the weight of a certain amount of matter.Sound transmits faster in light and hard matters. According to the chart above,the density of gaseous matter is smaller than that of liquid and solid matter is much larger than liquid matter and gaseous matter is the smallest.

For summary
※Click each parenthesis and the answer appears.
・Yarn phone is an example to prove that sound travels through(solid matters)
・The speed of sound is the fastest in (solid matters) and the most slowly in (gaseous matters)
・The speed of sound is different depending on the material of mediums.The key factors are (the dinst) and (modulus of elasticity)
                       ↑Mechanism of Sound@に進みます。

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