Question

$S_1$ and $S_2$ are two identical sound sources of frequency $656$ $Hz$. The source $S_1$ is located at $𝑂$ and $𝑆_2$ moves anti-clockwise with a uniform speed $4\sqrt2$ $m s ^{−1}$ on a circular path around $𝑂$, as shown in the figure. There are three points $𝑃$, $𝑄$ and $𝑅$ on this path such that $𝑃$ and $𝑅$ are diametrically opposite while $𝑄$ is equidistant from them. A sound detector is placed at point $𝑃$. The source $𝑆_1$ can move along direction $𝑂𝑃$. [Given: The speed of sound in air is $324$ $m s ^{−1}$ ]