Sound waves

(a)

Do YF 19-19 (p. 616).

(b)

What amplitude $A_o$ must a standing sound wave

$$s(x,t)=A_o \sin(kx) \cos(\omega t)$$

of frequency $f=440$ Hz (middle ``A'') have in order that the pressure change by $\pm 0.1 P_o$ at the point $x=0$? Use the following data: at sea level, the speed of sound is $c=344$ m/s, its density is $\rho_o=1.3$ kg/m$^3$, and air pressure is $P_o=1.01 \times 10^5$ N/m$^2$.
Note: Later we will learn how many ``decibels'' this would be.