Question

If an emergency vehicle passes you in traffic, just as it passes you the pitch ofthe siren changes. This is because:A. the frequency increases as the siren is moving toward you, anddecreases as it is moving away.B. the wave speed increases as the siren is moving toward you, anddecreases as it is moving away.C. the volume increases as the siren is moving toward you, anddecreases as it is moving away.D. the amplitude increases as the siren is moving toward you, anddecreases as it is moving away.SUBMIT

Answer 1

Given that an emergency vehicle passes you in traffic, just as it passes you the pitch of the siren increases. Let's determine why.

Just as the siren passes you, the drop is sound is due to Doppler's effect.

As the emergency vehicle approaches you, the sound increases but just as it passes you there is a drop in pitch in the siren's sound.

The pitch of sound depends on the frequency of the sound wave. As the vehicle approaches the frequency you observe increases which makes your ears hear a higher pitch. As the vehicle passes you, the observed frequency drops which in turn leads to a drop in pitch.

Therefore, the frequency increases as the siren is moving towards you, and decreases as it is moving away.

ANSWER:

A. ,the frequency increases as the siren is moving towards you, and decreases as it is moving away.