Physics - Sound Wave Question with Solution | TestHub

At $x=0,y=y_1+y_2=2A\cos 96\pi t\cos 4\pi t$ Frequency of $\cos (96\pi t)$ function is $48\mathrm{Hz}$ and that of $\cos (4\pi t)$ function is $2\mathrm{Hz}$. In one second cos function becomes zero at $2f$ times, where $f$ is the frequency. Therefore, first function will become zero at 96 times and the second at 4 times. But second overlaps with first. Hence, net $y$ will become zero 96 times in 1 second.