# Selina Solutions Class 8 Physics Solutions for Exercise Short/Long Answer Questions in Chapter 7 - Sound

Q1) How does sound travel in air?

Solution :

Sound is a mechanical wave which results from the back and forth vibrations of the particles of the air medium through which the sound wave is moving. These vibrations in the air are caused by the vibration of the objects that generates the sound.

Video transcript
"hello students welcome to Lido learning's question and answer videos my name is pallavi and i teach math and science at nero let's have a look at this interesting but easy question that is how does sound travel in air so we know that sound is a mechanical wave so what does what do you mean by mechanical wave it means that a medium is required for sound to travel so always we need a medium for sound to travel it's very much unlike light which is an electromagnetic wave and it does not require any medium to travel so now we have understood how what type of wave sound is right now let's talk about the propagation so sound is a mechanical wave which results from back and forth vibrations of the particles of air medium through which the sound wave is moving now to understand this let's say this is our sound wave this is our source from which the sound is coming as the source vibrates it makes the particles of the medium also vibrate back and forth along the propagation direction of propagation of the wave so again let's compare that to understand this better let's compare that to a light wave so when lightweight is called a transverse wave that is the particles in the medium they vibrate perpendicular to the direction of propagation of the wave so this is what happens in transverse waves whereas sound wave is called a longitudinal wave where the medium the particles in the medium these blue spots which you see here are the particles of the medium so they as you can see they are vibrating back and forth as the wave goes along and they are transferring the energy so these vibrations in the air are caused by vibration of the object that generates the sound so when this object is generating sound this also vibrates and as a result it pass the energy to the particles of the medium and that is how it keeps on going and that is how it reaches our ear that is this is the receiver so i hope you understood how sound travels in air so the main points from this video to be taken is sound is a mechanical wave which is also called a longitudinal wave and what do we mean by mechanical wave it means that the medium is required is required for sound to travel and the most important part is the particles of medium the particles of medium they are vibrating vibrate along the direction of propagation of the wave that is parallel to the direction of propagation of wave and not perpendicular to it so i hope you understood the meaning of how sound travels in it if you have any further questions please post your comments below thank you"
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