Question:
A person standing on a road sends a sound signal to the driver of a car going away from him at a speed of $72 \mathrm{~km} \mathrm{~h}^{-1}$. The signal travelling at $330 \mathrm{~m} \mathrm{~s}^{-1}$ in air and having a frequency of $1600 \mathrm{~Hz}$ gets reflected from the body of the car and returns. Find the frequency of the reflected signal as heard by the person.
Solution:
