Nokea
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 main idea of the passage?
- A. Trains and ambulances emit loud noises.
- B. Low-frequency waves produce high-pitched sounds.
- C. High-frequency waves result in low-pitched sounds.
- D. The Doppler Effect explains why sound is heard more strongly initially and then faintly after a moving object has passed.
Correct Answer: D
Rationale: The main idea of the passage is to explain the scientific phenomenon known as the Doppler Effect. The passage describes how when a train or ambulance moves towards a listener, sound waves are compressed, resulting in a higher frequency and pitch. Conversely, as the objects move away, the sound waves stretch, leading to a lower frequency and pitch. The Doppler Effect is the reason why sound is heard louder as the object approaches and then fades as it moves away. This explanation aligns with choice D, making it the correct answer.
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Food
Food and drink are necessary and desirable, but their
abuse can cause serious physical and metal problem.
Many physicians believe that overeating is one of the
country's main health problems, since it places a great
strain on the heart, can lead to diabetes, and often shortens
the individual's life span. To fill an emotional void. People
often turn to food when they are bored or lonely.
Another area of concern is alcohol consumption. The
results of alcohol abuse are widely publicized. The social
drinker who becomes alcoholic, the drunken driver's
contribution to highway death, spousal and child abuse,
are all concomitant problems associated with alcohol
abuse.
The author seems to?
- A. Oppose drinking alcohol
- B. Favor strict diet
- C. Oppose regulation of personal habits
- D. Favor moderation
Correct Answer: D
Rationale: The author discusses the negative consequences of overeating and alcohol abuse, highlighting the strain they place on health and the risks involved. The text emphasizes the importance of moderation by pointing out the dangers of excess in both food consumption and alcohol intake. Therefore, the author's stance appears to be in favor of moderation rather than strict dieting or complete opposition to personal habits like alcohol consumption.
The Moon has been worshipped by primitive peoples and has inspired humans to create everything from lunar calendars to love sonnets. But what do we really know about it? The most accepted theory about the Moon's origin is that it was formed from the debris of a massive collision with the young Earth about 4.6 billion years ago. A huge body, perhaps the size of Mars, struck the Earth, throwing out an immense amount of debris that coalesced and cooled in orbit around the Earth.The development of Earth is inextricably linked to the Moon; the Moon's gravitational influence upon the Earth is the primary cause of ocean tides. In fact, the Moon has more than twice the effect on the tides than the Sun. The Moon makes one rotation and completes a revolution around the Earth every 27 days, 7 hours, and 43 minutes. This synchronous rotation is caused by an uneven distribution of mass in the Moon (essentially, it is heavier on one side than the other) and has allowed the Earth's gravity to keep one side of the Moon permanently facing Earth.The average distance from Earth to the Moon is about 384,403 km. The Moon has no atmosphere; without it, the Moon has no protection from meteorite impacts, resulting in a surface covered with impact craters, both large and small. The Moon also has no active tectonic or volcanic activity, so the erosive effects of atmospheric weathering, tectonic shifts, and volcanic upheavals that tend to erase and reform the Earth’s surface features are not at work on the Moon. In fact, even tiny surface features, such as the footprint left by an astronaut in the lunar soil, are likely to last for millions of years unless obliterated by a chance meteorite strike. The surface gravity of the Moon is about one-sixth that of Earth's. Therefore, a person weighing 82 kilograms on Earth would only weigh 14 kilograms on the Moon. The geographical features of the Earth most similar to those of the Moon are places such as the Hawaiian volcanic craters and the huge meteor crater in Arizona. However, the climate of the Moon is very different from either Hawaii or Arizona; in fact, the temperature on the Moon ranges from 123 degrees Celsius to -233 degrees Celsius.
What is the passage primarily about?
- A. What we know about the Moon and its differences from Earth
- B. A comparison of the Moon and Earth
- C. The Moon's effect on Earth
- D. The origin of the Moon
Correct Answer: A
Rationale: The passage primarily discusses various aspects of the Moon, what is known about it, and how it differs from Earth. It covers topics such as the Moon's formation, gravitational influence on Earth, lack of atmosphere, surface features, gravity, and climate. While it mentions the Moon's origin and its effect on Earth, the main focus is on providing information about the Moon and highlighting its distinctions from Earth.
It is a well-known fact that it takes the Earth approximately 365 days to orbit the Sun. At the same time, the Earth revolves or spins around itself over the course of 24 hours, which explains why we experience day and night. One half of the Earth is always facing the Sun, while the other half is facing away. As a result, different time zones divide the globe. Moving suddenly from one time zone to another, such as when flying from Asia to North America, can cause jet lag. People often feel tired, wake up suddenly during the night, and cannot return to sleep. It takes time to adjust to a new time zone. Another important factor to consider is the slight tilt of the Earth toward the Sun. The Earth does not stand straight but leans slightly to one side. Therefore, when it revolves around the Sun, the middle part of the Earth is always closer to the Sun and receives more heat. This area is called the equator, and the regions above and below it are known as the tropics. Countries located in the tropics receive a consistent amount of daylight throughout the year, with the Sun rising at 6 AM and setting at 6 PM. In contrast, the tips of the Earth, or the poles, receive hardly any light because they are so far from the Sun. There are two main seasons at the poles: 6 months of summer, when the Sun is always shining (even at night), and 6 months of winter, characterized by constant darkness. Between the tropics and the poles lies the temperate zone, where there are four distinct seasons. The Sun rises and sets at different times throughout the year. In spring and summer, it gets light earlier; in fall and winter, it gets dark earlier. People living in temperate zones take advantage of this variation to maximize their daylight exposure. At the beginning of spring, countries in Europe and North America readjust their clocks by moving them an hour ahead. As a result, the Sun does not set around 7 or 8 PM as usual, but an hour later. This practice is called Daylight Savings Time (DST) and lasts until the beginning of fall, when people move their clocks back one hour to Standard or Regular Time. It is believed that Benjamin Franklin first suggested the introduction of Daylight Savings Time in the 18th century, but the first serious proposal came in 1907 from William Willet. However, his idea was shelved by the British government, which deemed it unnecessary. Daylight Savings Time was first implemented by the German government in 1916 in order to save energy during World War I. Shortly after, the United Kingdom followed suit, with the United States doing the same in 1918. The law was unpopular, as people had to wake up earlier, leading many to experience a feeling similar to jet lag. However, the energy crisis of the 1970s forced the U.S. to establish Daylight Savings Time as law. Studies showed that the introduction of Daylight Savings Time in the spring saved the U.S. 10,000 barrels of oil per day between 1974 and 1975. It also prevented 2,000 traffic injuries and 50 traffic-related deaths, saving the country $28 million. Currently, Americans switch to Daylight Savings Time on the first Sunday in April and revert to Standard Time on the last Sunday in October. As of 2007, the time adjustments occur even earlier in March and November.
If it is 7 p.m. Standard Time, what time is it for Daylight Savings Time?
- A. 6 p.m.
- B. 8 p.m.
- C. 7 a.m.
- D. 8 a.m.
Correct Answer: A
Rationale: When transitioning from Standard Time to Daylight Savings Time, the clock is moved forward by one hour. Therefore, if it is 7 p.m. Standard Time, it would be 8 p.m. in Daylight Savings Time. The correct answer is 6 p.m., reflecting the advancement of the clock by one hour during the Daylight Savings Time period.
The Summer Olympic Games. Once every four years the countries of the world send their best and brightest to participate in the Summer Olympic Games. The site for the event is decided years before, and most countries contend strongly for the privilege to host the Games. The 2008 games were held in Bejing, China.
There is a lot of pageantry and tradition attached to the event. The opening ceremony is elaborate and awe-inspiring. China put on a spectacularly beautiful fireworks display to welcome the world's athletes in 2008.
The track events, water events (swimming, diving) and precision activities such as archery and rhythmic gymnastics are wonderful to watch. Seeing these athletes perform their special skills is a treat for those of us who achieve a vicarious satisfaction from it. Everyone roots for the athletes from their own country and we thrill when our anther is played during the medal ceremony. Being an Olympian is an honor every athlete dreams of.
What is the meaning of the word 'roots' as used in the third paragraph?
- A. The part of a plant under the ground.
- B. To wish the success of.
- C. A musical tone upon which a piece of music is based.
- D. To dig in the earth with a snout.
Correct Answer: B
Rationale: In the context of the third paragraph, the word 'roots' is used to describe how people support and cheer for the athletes from their own country. 'To wish the success of' is the correct interpretation, making choice B the correct answer. The other definitions of 'roots' refer to different meanings that do not fit the context of cheering for athletes.
Electrocardiogram
The rhythmic sounds of "beep... beep... beep..." signify the measurement of the heart muscle's strength. This rhythmic signal varies from person to person and is recorded as an electrocardiogram (ECG). Within the body, a complex array of systemic neural responses generates electric currents that can be detected on the skin's surface. When a person is connected to an amplifier, these impulses are captured by an electrocardiograph. Most of the information gathered pertains to the heart, as it emits electric currents in waves. This "wave of excitation" propagates through the heart wall and is associated with electrical changes. The process occurs in three distinct phases. First, the "wave of excitation," accompanied by an electrical change, lasts for about 1 to 2 seconds following the contraction of the cardiac muscle. These electrical impulses are rhythmically discharged from the sinoatrial (SA) node, which acts as the heart's natural pacemaker, signaling the atrium to contract. The peak of the ECG reading is attributed to the atrioventricular (AV) node, which triggers the excitation of the ventricles. Finally, as the ventricles relax, any changes in the wave pattern can alert trained medical personnel to potential abnormalities within the heart.
What is the best summary of the passage?
- A. Electric currents within the body are due to electrostatic charges set off by the heart. Medical staff are trained to recognize any abnormalities within the heart.
- B. Every individual has unique electric currents on the surface of the body. The ECG measures and records these electric currents.
- C. The ECG systematically and rather quickly measures the stages at which the "wave of excitation" occurs within the heart and records them. This wave has three distinct steps that spread from the SA node to the AV node.
- D. The ECG measures the electric currents within the body. These currents are detected on the surface of the body when the body is connected to an amplifier.
Correct Answer: C
Rationale: The correct answer is C because it accurately summarizes the passage by highlighting that the ECG systematically measures the stages of the 'wave of excitation' within the heart. This wave has three distinct steps that spread from the SA node to the AV node. The other options either focus on general information about electric currents or do not capture the specific details provided in the passage about the ECG and the heart's electrical activity.