# An operator sitting in his base camp sends a sound signal

Question:

An operator sitting in his base camp sends a sound signal of frequency $400 \mathrm{~Hz}$. The signal is reflected back from a car moving towards him. The frequency of the reflected sound is found to be $410 \mathrm{~Hz}$. Find the speed of the car. Speed of sound in air $=324 \mathrm{~m} \mathrm{~s}^{-1}$.

Solution: