Question

A police car is parked by the side of a highway and its siren emits a sound measuring 750 Hz. As you approach the police car from a distance, you hear a change in the sound. The change is in the sound's A) frequency. B) pitch and frequency. C) frequency and wavelength. D) pitch, intensity, and loudness.

Answer 1

This is called the Doppler effect. It's essentially a compression of the sound wave. When the sound wave compresses, the wavelength is therefore decreased. Becasue frequency is inversely related to the wavelength, the frequency is changed as well.

F = v/λ

F - frequency
v - velocity
λ - wavelength

Answer 2

D) pitch and frequency

Explanation:

If it's USATestprep it's D I just answered this one.