Nokea
Doppler Effect
Have you ever wondered why the whistle of a traveling, distant locomotive predicts its approach several yards before anyone actually sees it? Or why an oncoming ambulance's screaming siren is 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 toward the 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 higher pitch. 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.
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
Correct Answer: C
Rationale: In the context of the passage, the word 'phenomenon' refers to something that is significant but unusual. The Doppler Effect described is a scientific phenomenon, meaning it is an observable event that is noteworthy and not commonly encountered. It is not related to being lifeless, nonchalant, or having a chemical origin. The explanation in the passage clearly illustrates how the Doppler Effect is a remarkable occurrence that affects the perception of sound based on the relative motion of the source and the listener.
You may also like to solve these questions
Which sentence is grammatically correct?
- A. The dog catches the Frisbee well.
- B. The band did well during the halftime show.
- C. Sarah plays her new saxophone well.
- D. The band that played before ours was good.
Correct Answer: C
Rationale: In English, 'well' is the appropriate adverb used to describe how an action is performed. 'Good' is an adjective and should not be used to describe actions. Therefore, the correct sentence is 'Sarah plays her new saxophone well.'
Lightning Strikes
The old wives' tale of "Lightning never strikes twice" has been proven untrue time and time again. Lightning forms from negative and positive charges within clouds and from the earth below. When these charges react with each other, the air between the cloud and the earth ionizes, which produces a lightning flash. Lightning is actually a series of multiple events consisting of a leader stroke of lightning, followed by as many as 40 smaller strokes of lightning. Being just split seconds apart, these strokes of lightning often reflect off the lining of the clouds.
Lightning rods that extend from above the roof to the ground protect buildings by forming a low resistance path for the lightning so that the lightning does not enter the building, but rather defuses as it penetrates the ground.
Some myths about lightning need to be explained. Lightning does strike tall buildings often, and during a particularly violent storm, a tall building may be hit by lightning several times. The safest place during a thunder and lightning storm is in a metal car or lying flat, face down, in the open, not under a tree as the myth suggests.
Many people believe that thunder and lightning are connected; however, this proves to be true only about 50% of the time, so if you're waiting for the clap of thunder, you're missing out on some exciting strokes of lightning!
Lightning causes injuries, deaths, and forest fires each year. However, some scientists reveal the positive aspects of lightning because it releases nitrogen into the atmosphere which the raindrops then deliver to earth to fertilize our soil.
Based on the provided information, the reader can conclude that lightning:
- A. Always consists of a single stroke
- B. Is harmless and does not pose any risk
- C. Consists of a main stroke and several smaller strokes
- D. Only occurs during thunderstorms
Correct Answer: C
Rationale: The correct answer is C: 'Consists of a main stroke and several smaller strokes'. The text explains that lightning is actually a series of multiple events, starting with a leader stroke followed by as many as 40 smaller strokes of lightning. This information contradicts choice A, which suggests lightning always consists of a single stroke. Choice B is incorrect because the text clearly states that lightning causes injuries, deaths, and forest fires, indicating that it poses risks. Choice D is incorrect as lightning rods protect buildings even when there is no thunderstorm, suggesting that lightning can occur independently of thunderstorms. Therefore, the conclusion drawn from the text is that lightning consists of a main stroke and several smaller strokes, making option C the correct answer.
Laughter: One of the best ways to understand a group of people is to know what makes them laugh. Laughter encompasses the limits of the soul and serves social, psychological, and physiological functions. In humor, life is redefined and accepted. Irony and satire provide much deeper insights into a group's collective psyche and values than do years of research. It has always been a great disappointment to Native Americans that the humorous side of their life has not been mentioned by experts on Native American affairs. Rather, the image of the stern-faced redskin has been presented by the American Westerns.
The author seems to
- A. take an impartial view on the issue.
- B. favor the current image of the Native Americans.
- C. oppose spending money on Native American affairs.
- D. favor research into Native American humor.
Correct Answer: D
Rationale: The correct answer is D because the author expresses disappointment that experts on Native American affairs have not mentioned the humorous side of their life. This indicates a favor towards research into Native American humor.
A is incorrect because the author shows a clear opinion on the issue by expressing disappointment. B is incorrect as the author criticizes the current image of Native Americans. C is incorrect as there is no mention of opposing spending money on Native American affairs.
In summary, the author favors research into Native American humor as it is highlighted as a neglected aspect that should be explored further.
Electrocardiogram
Beep!Ć¢Ä‚¬Ā¦Beep!Ć¢Ä‚¬Ā¦Beep! is the audible rhythmic sound made as the strength of the heart muscle is measured. 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 an amplifier, these impulses are recorded by an electrocardiograph.
Most of the information obtained is about the heart because the heart sends out electric currents in waves. This Ć¢Ä‚¬Å“wave of excitationĆ¢Ä‚¬Ā¯ spreads through the heart wall and is accompanied by electric changes. The wave takes place in three distinct steps.
Initially, the Ć¢Ä‚¬Å“wave of excitationĆ¢Ä‚¬Ā¯ accompanied by an electric change lasts for approximately 1 to 2 seconds after the contraction of the cardiac muscle. The electric impulses are discharged rhythmically from the sinoatrial (SA) node, the pacemaker of the heart. This spread of excitation over the muscle of the atrium indicates that the atrium has contracted.
Next, the peak of the ECG reading is due to the atrioventricular (AV) node, causing the ventricle to become excited.
Finally, the ventricles relax, and any changes in the wave indicate to trained medical staff any abnormalities within the heart.
What are the three steps of the 'wave of excitation' during an electrocardiogram?
- A. The discharge from the SA node, the peak ECG, and the excitement of the ventricle.
- B. The excitement of the ventricle, the relaxing of the ventricle, and the systemic neural response.
- C. The contraction of the atrium, the relaxation of the atrium, and the contraction of the ventricle.
- D. The excitation of the atrium, the excitement of the ventricle, and the relaxing of the ventricle.
Correct Answer: D
Rationale: The correct sequence of the 'wave of excitation' during an electrocardiogram includes the excitation of the atrium (contraction), the excitement of the ventricle (peak ECG), and the relaxing of the ventricle. This process starts with the discharge from the SA node, followed by the peak ECG due to the AV node, and ends with the relaxation of the ventricles. Understanding this sequence is crucial for interpreting ECG readings accurately and identifying any abnormalities within the heart.
Croatian-born inventor Nikola Tesla is often called the "forgotten scientist". Although he
invented the alternating current (AC) motor and developed an AC electricity generation system, he never received historical credit for many of his achievements, unlike one of his first employer and eventual nemesis, inventor Thomas Edison
Tesla made the first sketches of his idea for a brushless of his idea for a brushless AC motor while he was a student at the University of Prague in 1882. His interest in electricity generation led him to Paris where he was employed by the Continental Edison Company later that year to repair Edison's direct current (DC) power plants. Two years later, Tesla immigrated to New York City and acquired a job as an engineer at
Thomas Edison's headquarters in Manhattan. Edison was impressed with Tesla's work ethic and
ingenuity. He challenged the young scientist to develop an improved design for his DC
generators for $50,000. Tesla experimented for months, finally presenting Edison with the
solution he needed. Edison reneged on the deal, telling Tesla that he didn't understand American humor. Tesla soon left Edison in order to begin his own electric light company
Tesla filed and was granted more than 30 patents for his inventions in 1887 and 1888. He soon
had financial backing for his ideas from one of Edison' main competitors, Westinghouse. In the
1890's Tesla experimented with x-rays, developed a high-voltage electrical transformer call the
Tesla coil, and demonstrated the propagation of radio waves two years before the "Father of
Radio" Guglielmo Marconi. He was also the first to harness the mammoth potential energy of
Niagara Falls. He worked with General Electric to install AC generators with turbines driven by the falling waters of the Niagara River, creating the first modern power plant although a brilliant scientist, Tesla was not an astute businessman. He created his own obscurity by relinquishing
royalty rights for his inventions to major corporations for the purpose of raising funds for future projects.
What is the meaning of the word obscurity as it is used in the last paragraph?
- A. Poverty
- B. Celebrity
- C. Confusion
- D. Insignificance
Correct Answer: D
Rationale: The word 'obscurity' in the context of the passage refers to being unknown or in the state of insignificance. Nikola Tesla, despite his significant scientific contributions, did not gain the recognition or fame he deserved due to his decisions to relinquish royalty rights for his inventions. This led to his work being underappreciated and him remaining in obscurity, meaning he was not recognized or valued as he should have been. Therefore, the correct answer is 'Insignificance.'