Problem 6.183

There is a square membrane of area $S .$ Find the number of natural vibrations perpendicular to its plane in the frequency interval from $\omega$ to $\omega+d \omega$ if the propagation velocity of vibrations is equal to $v$ .

d N_{\omega}=\left(S / 2 \pi v^{2}\right) \omega d \omega

Molecules and Crystals