All Problems Elastic Waves. Acoustics.
Problem 4.187
A point \(A\) is located at a distance \(r=1.5 \mathrm{~m}\) from a point isotropic source of sound of frequency \(v=600 \mathrm{~Hz} .\) The sonic power of the source is \(P=0.80 \mathrm{~W}\). Neglecting the damping of the waves and assuming the velocity of sound in air to be equal to \(v=340 \mathrm{~m} / \mathrm{s}\) find at the point \(A\) : (a) the pressure oscillation amplitude \((\Delta p)_{m}\) and its ratio to the air pressure; (b) the oscillation amplitude of particles of the medium; compare it with the wavelength of sound.
4.187. (a) \((\Delta p)_{m}=\sqrt{\rho v P / 2 \pi r^{2}}=5 \mathrm{~Pa}, \quad(\Delta p)_{m} / p=5 \cdot 10^{-5} ;\) (b) \(a=(\Delta p)_{m} / 2 \pi v \rho v=3 \mu m, a / \lambda=5 \cdot 10^{-6}\)