Question

You are driving down the highway when a police car with a siren sounding passes you. If the rest frequency of the siren is f₀, what happens to the frequency you hear while the car is catching up to you?

A) It remains the same as f₀.
B) It is higher than f₀.
C) It is lower than f₀.
D) It fluctuates randomly.

Answer 1

The frequency you hear as a police car with a siren approaches you is higher than the rest frequency () due to the Doppler effect.

Step-by-step explanation:

When a police car with a siren sounding passes you, the frequency of the sound you hear while the car is catching up to you is higher than f₀. This is because of the Doppler effect, which refers to the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. If you are stationary and the source of the sound (in this case, the police siren) is moving towards you, the sound waves are compressed, leading to a higher frequency. Conversely, as the police car drives away from you, the sound waves will stretch out, resulting in a lower frequency than the original. Therefore, the correct answer to the question is B) It is higher than f₀.