Problem 4.159

A point isotropic source generates sound oscillations with frequency $v=1.45 \mathrm{kHz}$. At a distance $r_{0}=5.0 \mathrm{~m}$ from the source the displacement amplitude of particles of the medium is equal to $a_{0}=50 \mu \mathrm{m},$ and at the point $A$ located at a distance $r=10.0 \mathrm{~m}$ from the source the displacement amplitude is $\eta=3.0$ times less than $a_{0} .$ Find: (a) the damping coefficient $\gamma$ of the wave; (b) the velocity oscillation amplitude of particles of the medium at the point $A$.