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 author's primary purpose in writing this passage?
- A. To entertain the reader with information about trains and ambulances
- B. To inform the reader about avoiding accidents involving trains and ambulances
- C. To inform the reader about how movement affects sound
- D. To analyze the difference between train and ambulance sounds
Correct Answer: C
Rationale: The correct answer is C. The author's primary purpose in writing this passage is to inform the reader about how movement affects sound, specifically focusing on the Doppler Effect. The author explains how sound waves change when a source of sound is in motion, leading to differences in pitch perceived by a listener. The passage aims to educate readers on this scientific phenomenon rather than entertain, provide safety tips, or compare train and ambulance sounds, making option C the most fitting choice.
You may also like to solve these questions
Subjective exams measure your ability in several areas. Besides recall information, you must be
able to realize content logically and intelligently express yourself in a clearly understood manner. Subjective test provide opportunity for students to show their broad knowledge of a subjective
area. Answers may be in the form of paragraphs or lengthy essays. When your review for an essay exam, concentrate on main ideas rather than details. Since essay tests are less to a few questions, they are likely to deal with more important ideas of a subject. Prepare a list of question you think might be asked. Write an answer to each of your questions. Rather than writing complete sentence down your thoughts in outline form. Doing so will help
you organize the information so that you can express yourself clearly.
When you take the test, read through all the questions before you start to write. Allot time for each question, spending more time for questions worth the most points. Read each question carefully to determine exactly what they are asked. Pay attention to words such as define, illustrate, explain, list, compare, and contrast. Each work requires a different type of response. Write a brief outline of your answer on scrap paper or the back of the test. Make sure you include all the important ideas that are within the limits of the question. In other words, do not write more than is asked for each answer. When you write your answer, keep it specific and as brief as possible. In the introductory sentence it is often helpful to make a general statement that includes
important points addressed in each question. Such a topic sentence serves as a framework for your answer. Then use your outline to develop the main point and subtopics. Add substance to
your answer by including as many facts as possible to support your answer.
Check your paper before you submit it. Look for mistakes in grammar, spelling, sentence
structure, and punctuation. Unless you are certain an answer is wrong, do not change it. Your answer is an educated guess and is usually your best chance of answering correctly.
In the above passage, the word 'subjective' refers to test questions that:
- A. Allow you to choose an answer
- B. Are matching
- C. Are true or false
- D. Require you to write your own answer
Correct Answer: D
Rationale: The term 'subjective' in the passage refers to test questions that require you to write your own answer, as mentioned in the text. Subjective tests typically involve expressing your understanding and knowledge in your own words, often through paragraphs or essays. This type of assessment allows students to demonstrate their comprehension and analytical skills by formulating responses based on their interpretation of the content, rather than selecting from predefined options. Therefore, the correct answer is D: 'Require you to write your own answer.'
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.
Glass
I wonder who first discovered glass. This commodity has been a part of civilization from the very beginning. Imagine a world without glass! How dark and dismal it would be. No windows, corrective lenses, telescopes, microscopes, cameras, sparkly drinking containers or mirrors. Life would not be the same without this wonderful discovery. Thank you, whoever found glass!
Glass is not an element, but a combination of several elements. It is a hard, brittle, transparent solid material composed mainly of silica, with additives to change the character of the glass. Common additives are soda, lime, lead, and boron. Each additive changes the properties of the final product. Soda and lime are the most common additives, accounting for about 90% of glass production. Adding lead increases reflectivity, causing the glass to "sparkle." The addition of boron changes the thermal and electrical properties of glass, allowing cookware that can be used in the oven without shattering.
What conclusion can be drawn from the information included in the article?
- A. New uses for glass are constantly being discovered.
- B. Glass is no longer used in modern technology.
- C. The production of glass is declining rapidly.
- D. Glass is too brittle to be used in new applications.
Correct Answer: A
Rationale: The article discusses the various uses and properties of glass, highlighting its significance in everyday life. It mentions that glass is a versatile material with different additives that change its properties, allowing for diverse applications such as windows, lenses, telescopes, and cookware. The article does not suggest that glass usage is decreasing or that it is too brittle for new applications. Therefore, the most appropriate conclusion from the information provided is that new uses for glass are constantly being discovered, as its properties and versatility continue to be explored.
Over the last few decades, medical experts have changed their thinking on the health effects of some common foods and beverages. Higher-fat foods and some alcoholic beverages like red wine and beer, once viewed as top threats to a healthy lifestyle, are now seen by many as less harmful and even as having some health benefits. But there is perhaps no topic that the medical community has reversed its
thinking on more often than coffee. Since long before the advent of modern medicine, public opinion regarding the health effects of coffee has been diverse and ever-changing. Opinion on coffee's health effects can be traced back several centuries. In the 1600s, doctors in England touted coffee as a cure for alcoholism, but some women complained that coffee was making their husbands impotent. They may have been correct, as caffeine is a
diuretic and can irritate the prostate (dehydration and prostatitis can both lead to erectile dysfunction). In the late 1700s, coffeehouses began opening all over colonial America, where coffee was seen as a healthy stimulant that helped the colonists work longer hours. But by the early 1900s, public concern grew as coffee consumption was blamed for a variety of common ailments, such as nervousness, indigestion, and insomnia. In the 1970s, medical journals published studies that linked coffee consumption with high blood pressure and an increased risk of heart attacks. In 2001, a meta-study indicated that coffee was responsible for a 20% increase in risk for urinary tract cancer. But starting in 2007, to the surprise of many, meta-studies began to show positive health effects of coffee consumption. A 2007 study showed that coffee was viewed by many as "practically a health food." However, CNN also warned that given the long history of flip-flops on the health effects of coffee, medical and public opinion on coffee could easily turn negative again.
Which statement is supported by the passage?
- A. In the 2000s, studies showed negative health effects of coffee consumption.
- B. In the 1600s, some believed that coffee caused erectile dysfunction.
- C. In the late 1900s, public opinion on coffee shifted from positive to negative.
- D. In the 1800s, American colonists saw coffee as a healthy stimulant.
Correct Answer: A
Rationale: The passage discusses the changing opinions on the health effects of coffee over different time periods. It mentions that in the 1600s, some women complained that coffee was making their husbands impotent, which supports the idea of negative health effects. It also highlights that in the 2000s, studies showed positive health effects of coffee consumption, indicating a shift in thinking. Therefore, choice A is the statement supported by the passage, as it aligns with the information provided.
Blood Pressure Regulators
The body comprises systems that have evolved and diversified to maintain essential functions and processes. One such system is the cardiovascular system, which includes critical regulators of blood pressure. The heart serves as the body’s pump, ensuring a steady flow of vital oxygen to all cells while facilitating the removal of carbon dioxide and other waste products. Given that blood pressure varies at different points throughout the body, various components are necessary to regulate it effectively. Three primary components involved in blood pressure regulation are baroreceptors, chemoreceptors, and the kidneys. Baroreceptors, which are stretch receptors made up of fine branching nerve endings, are located along the walls of arteries near the heart and in other areas of the body. When these baroreceptors detect stretching in the arterial walls, they send impulses to the heart, arteries, and veins, leading to an increase or decrease in blood pressure. Chemoreceptors, found along the walls of the arteries, monitor changes in oxygen levels, carbon dioxide, and pH. For instance, a drop in oxygen levels triggers these receptors to send impulses that raise blood pressure. The kidneys also play a crucial role in blood pressure regulation by absorbing salts and water while eliminating waste. Hormones secreted by the adrenal cortex influence the kidneys to retain or excrete salt and water, thereby affecting blood volume and, consequently, blood pressure.
In the context provided, what does the term 'evolved' mean?
- A. To spread
- B. To gradually develop
- C. To revolve
- D. To shift
Correct Answer: B
Rationale: The correct answer is B: 'To gradually develop.' In the context provided, 'evolved' refers to the gradual development and diversification of systems within the body to maintain the natural functions and processes they regulate. Evolution implies a process of advancement and adaptation over time, aligning with the concept of gradual development.