HESI A2 VERSION 1READING COMPEHENSIONDoppler EffectHave you ever wondered why the whistle of a traveling, distant locomotive predicts its approachseveral yards before anyoneactually sees it? Or why an oncoming ambulance’s screaming sirenis heard momentarily several feet before the ambulance comes into full view, before it passesyou, and why its siren is still heard faintly well after the ambulance is out of sight?What youare witnessing is a scientific phenomenon known as the DopplerEffect. What takesplace is truly remarkable. In both of these instances, when the train or ambulance moves towardthe sound waves in front of it, the sound waves are pulled closer together andhave a higherfrequency. In either instance, the listener positioned in front of the moving object hears a higherpitch. The ambulance and locomotive are progressively moving away from the sound wavesbehind them, causing the waves to be farther apart andto have a lower frequency. These fast-approaching modes of transportation distance themselves past the listener, who hears a lowerpitch.1.Which statement is not listed as a detail in the passage?A.The oncoming sound waves have a higher pitch becauseof high frequency and closenessof waves.B.The oncoming sound waves have a higher pitch because of low frequency and closenessof waves.C.The whistling sound of the locomotive as it approaches and passes can be explained bythe Doppler effect.D.The high-pitched sound of the ambulance as it approaches and passes can be explainedby the Doppler effect.2.What is the main idea of the passage?A.Trains and ambulances make distinctly loud noises.B.Low-frequency waves make high-pitched sounds.C.High-frequency waves make low-pitched sounds.D.The DopplerEffectexplains the rationale for why sound is heard initially more stronglyand then faintly after a moving object has passed.3.What is the meaning of the word phenomenon in the second paragraph?A.Something that is lifeless to the sensesPreview Mode
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