Question

A fire truck emits sound waves at a constant frequency. An observer stands several blocks away. Which statement best describes the sound waves perceived by the observer as the fire truck approaches?
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1 point
The wavelength and frequency both decrease.
The wavelength decreases and the frequency increases.
The frequency and wavelength remain the same.
The wavelength increases and the frequency decreases.

Answer 1

As the fire truck approaches the observer, the observer experiences the Doppler effect, which causes the frequency of the sound waves to appear higher (increased frequency) and the wavelength to appear shorter (decreased wavelength).

Therefore, the correct statement is:
**The wavelength decreases and the frequency increases.**