It's the Doppler Effect that "up and down sound."
I was on Yahoo--- Brainly doesn't have an option for Credientials or Site credit, so I'll just put this in the quotes:
<span>The formula for doppler effect is always (s is speed and f is frequency): </span>
<span>f_perceived.by.observer = f_of.emitted.wave * (s_wave + s_observer) / (s_wave + s_source.of.wave) </span>
<span>And you should pay attention to the signs: </span>
<span>s_observer is positive if the receiver is moving towards the source, negative otherwise </span>
<span>s_source.of.wave is positive if the source is moving away from the observer, negative otherwise </span>
<span>Applying it to this case: </span>
<span>s_source.of.wave = ? (positive), speed of ambulance </span>
<span>s_observer = + 2.44 m/s speed cyclist </span>
<span>f_of.emitted.wave =1800 Hz frequency of whine </span>
<span>f_perceived.by.observer = 1760 frequency heard by cyclist </span>
<span>s_wave = 343 m/s speed of sound in air </span>
<span>Now you know every value in the equation for doppler effect except by s_source.of.wave, so you can solve for s_source.of.wave.</span>
Answer:
Most of what we know about the interior of the Earth comes from the study of seismic waves from earthquakes. Seismic waves from large earthquakes pass throughout the Earth. These waves contain vital information about the internal structure of the Earth.
