Question:
A traffic policeman standing on a road sounds a whistle emitting the main frequency of $2.00 \mathrm{kHz}$. What could be the apparent frequency heard by a scooter-driver approaching the policeman at a speed of $36.0 \mathrm{~km} \mathrm{~h}^{-1}$ ? Speed of sound in air = $340 \mathrm{~m} \mathrm{~s}^{-1}$.
Solution:
