COVERED
READING COMPEHENSION
Doppler Effect
Have you ever wondered why the whistle of a traveling, distant locomotive predicts its
approachseveral yards before anyone actually sees it? Or why an oncoming
ambulance’s screaming sirenis heard momentarily several feet before the ambulance
comes into full view, before it passes you, and why its siren is still heard faintly well
after the ambulance is out of sight?
What you are witnessing is a scientific phenomenon known as the Doppler Effect.
What takes place 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 and have a higher frequency. 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 waves behind them, causing the waves to
be farther apart and to have a lower frequency. These fast- approaching modes of
transportation distance themselves past the listener, who hears a lower pitch.
1. Which statement is not listed as a detail in the passage?
A. The oncoming sound waves have a higher pitch because of 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 Doppler Effect explains 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 senses
,B. Something that is nonchalant
C. Something that is significant but unusual
D. Something that is chemical in origin
4. What is the author’s primary purpose in writing this essay?
A. To entertain the reader with information about trains and ambulances
B. To inform the reader about avoiding accidents, which involve trains and
ambulances
C. To inform the reader about how movement affects sound
D. To analyze the difference between train and ambulance sounds
5. Which sound waves have a higher pitch?
A. Those waves that are closer together
B. Those waves that are farther apart
C. Those waves that travel a long distance
D. Those waves that travel a short distance
6. Which sound waves have a lower pitch?
A. Those waves that are closer together
B. Those waves that are farther apart
C. Those waves that travel a long distance
D. Those waves that travel a short distance
Electrocardiogram
Beep!…Beep!…Beep! is the audible rhythmic sound made as the strength of the heart
muscle ismeasured. The signal cadence has a characteristic record that varies in
every individual. This record is called an electrocardiogram, or ECG.
In the body, an array of systemic neural responses constantly occur, emitting electric
currents. The electric currents can be detected on the surface of the body, and if a
person is hooked to anamplifier, these impulses are recorded by an electrocardiograph.
Most of the information obtained is about the heart because the heart sends out
electric currentsin waves. This “wave of excitation” spreads through the heart
wall and is accompanied by electric changes. The wave takes place in three distinct
steps.
, Initially, the “wave of excitation” accompanied by an electric change lasts for
approximately 1to 2 seconds after the contraction of the cardiac muscle. The electric
impulses are discharged