Let us consider sound (longitudinal) wave(adsbygoogle = window.adsbygoogle || []).push({});

y=A.sin([tex]\omega[/tex]t-kx)

See attachment for diagram

Consider air column of length [tex]\Delta[/tex]x and cross-sectional area S at distance x from source.

I want to derive the pressure equation of the sound wave using

Bulk modulus, B=-[tex]\Delta[/tex]P/([tex]\Delta[/tex]V/V)

implying [tex]\Delta[/tex]P=-B.[tex]\Delta[/tex]V/V

But the trouble is that I am not able to select the expression for [tex]\Delta[/tex]V

1) [tex]\Delta[/tex]V=S.y

2) [tex]\Delta[/tex]V=S[tex]\Delta[/tex]y

TELL ME WHICH EXPRESSION OUT OF THE TWO SHOULD I USE withEXPLANATION.

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# Pressure equation of sound wave

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