Chapter 19 Sound Waves
Molecules obey SHM s(x,t)=smcos(kx-?t)
leads to variations in density and pressure in the air
pressure is large where density is large but displacement s(x,t) is small
hence pressure(or density) wave
is 900 out of phase with displacement
p=p0 + ?pm cos(kx-?t-?/2) = p0 + ?pm sin(kx-?t) (?p is change in pressure relative to equilibrium)
?= ?0 + ??m sin(kx-?t) “rho”