Question:
A source emitting sound at frequency $4000 \mathrm{~Hz}$, is moving along the $Y$-axis with a speed of $22 \mathrm{~m} \mathrm{~s}^{-1}$. A listener is situated on the ground at the position $(660 \mathrm{~m}, 0)$. Find the frequency of the sound received by the listener at the instant the source crosses the origin. Speed of sound in air $=330 \mathrm{~m} \mathrm{~s}^{-1}$.
Solution:
