QUESTION 1

The questions in this group are based on the content of this passage.  After reading the passage, choose the best answer to each question.  Answer all questions following the passage on the basis of what is stated or implied in the passage.

Originally, scientists predicted small asteroids to be hard and rocky, as any loose surface material (called regolith) generated by impacts was expected to escape their weak gravity. Aggregate small bodies were not thought to exist, because the slightest sustained relative motion would cause them to separate. But observations and computer modeling are proving otherwise. Most asteroids larger than a kilometer are now believed to be composites of smaller pieces. Those imaged at high-resolution show evidence for copious regolith despite the weak gravity. Most of them have one or more extraordinarily large craters, some of which are wider than the mean radius of the whole body. Such colossal impacts would not just gouge out a crater—they would break any monolithic body into pieces. In short, asteroids larger than a kilometer across may look like nuggets of hard rock but are more likely to be aggregate assemblages—or even piles of loose rubble so pervasively fragmented that no solid bedrock is left.

The rubble hypothesis, proposed decades ago by scientists, lacked evidence, until the planetologist Schumaker realized that the huge craters on the asteroid Mathilde and its very low density could only make sense together: a porous body such as a rubble pile can withstand a battering much better than an integral object. It will absorb and dissipate a large fraction of the energy of an impact; the far side might hardly feel a thing. At first, the rubble hypothesis may appear conceptually troublesome. The material strength of an asteroid is nearly zero, and the gravity is so low one is tempted to neglect that too. The truth is neither strength nor gravity can be ignored. Paltry though it may be, gravity binds a rubble pile together. And anybody who builds sandcastles knows that even loose debris can cohere. Oft-ignored details of motion begin to matter: sliding friction, chemical bonding, damping of kinetic energy, etc. We are just beginning to fathom the subtle interplay of these minuscule forces.

The size of an asteroid should determine which force dominates. One indication is the observed pattern of asteroidal rotation rates. Some collisions cause an asteroid to spin faster; others slow it down. If asteroids are monolithic rocks undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution with a statistical “tail” of very fast rotators. If nearly all asteroids are rubble piles, however, this tail would be missing, because any rubble pile spinning faster than once every two or three hours fly apart. Recently, several astronomers discovered that all but five observed asteroids obey a strict rotation limit. The exceptions are all smaller than about 150 meters in diameter, with an abrupt cutoff for asteroids larger than 200 meters. The evident conclusion—that asteroids larger than 200 meters across are rubble piles—agrees with recent computer modeling of collisions. A collision can blast a large asteroid to bits, but those bits will usually be moving slower than their mutual escape velocity (the lowest velocity that a body must have in order to escape the orbit of a planet). Over several hours, gravity will reassemble all but the fastest pieces into a rubble.

How would the author of the passage most likely respond to the assertion of another scientist claiming that a crater greater than the radius of an asteroid is a result of an impact?

QUESTION 2

The questions in this group are based on the content of this passage.  After reading the passage, choose the best answer to each question.  Answer all questions following the passage on the basis of what is stated or implied in the passage.

Originally, scientists predicted small asteroids to be hard and rocky, as any loose surface material (called regolith) generated by impacts was expected to escape their weak gravity. Aggregate small bodies were not thought to exist, because the slightest sustained relative motion would cause them to separate. But observations and computer modeling are proving otherwise. Most asteroids larger than a kilometer are now believed to be composites of smaller pieces. Those imaged at high-resolution show evidence for copious regolith despite the weak gravity. Most of them have one or more extraordinarily large craters, some of which are wider than the mean radius of the whole body. Such colossal impacts would not just gouge out a crater—they would break any monolithic body into pieces. In short, asteroids larger than a kilometer across may look like nuggets of hard rock but are more likely to be aggregate assemblages—or even piles of loose rubble so pervasively fragmented that no solid bedrock is left.

The rubble hypothesis, proposed decades ago by scientists, lacked evidence, until the planetologist Schumaker realized that the huge craters on the asteroid Mathilde and its very low density could only make sense together: a porous body such as a rubble pile can withstand a battering much better than an integral object. It will absorb and dissipate a large fraction of the energy of an impact; the far side might hardly feel a thing. At first, the rubble hypothesis may appear conceptually troublesome. The material strength of an asteroid is nearly zero, and the gravity is so low one is tempted to neglect that too. The truth is neither strength nor gravity can be ignored. Paltry though it may be, gravity binds a rubble pile together. And anybody who builds sandcastles knows that even loose debris can cohere. Oft-ignored details of motion begin to matter: sliding friction, chemical bonding, damping of kinetic energy, etc. We are just beginning to fathom the subtle interplay of these minuscule forces.

The size of an asteroid should determine which force dominates. One indication is the observed pattern of asteroidal rotation rates. Some collisions cause an asteroid to spin faster; others slow it down. If asteroids are monolithic rocks undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution with a statistical “tail” of very fast rotators. If nearly all asteroids are rubble piles, however, this tail would be missing, because any rubble pile spinning faster than once every two or three hours fly apart. Recently, several astronomers discovered that all but five observed asteroids obey a strict rotation limit. The exceptions are all smaller than about 150 meters in diameter, with an abrupt cutoff for asteroids larger than 200 meters. The evident conclusion—that asteroids larger than 200 meters across are rubble piles—agrees with recent computer modeling of collisions. A collision can blast a large asteroid to bits, but those bits will usually be moving slower than their mutual escape velocity (the lowest velocity that a body must have in order to escape the orbit of a planet). Over several hours, gravity will reassemble all but the fastest pieces into a rubble.

The primary purpose of the passage is to

QUESTION 3

The questions in this group are based on the content of this passage.  After reading the passage, choose the best answer to each question.  Answer all questions following the passage on the basis of what is stated or implied in the passage.

Originally, scientists predicted small asteroids to be hard and rocky, as any loose surface material (called regolith) generated by impacts was expected to escape their weak gravity. Aggregate small bodies were not thought to exist, because the slightest sustained relative motion would cause them to separate. But observations and computer modeling are proving otherwise. Most asteroids larger than a kilometer are now believed to be composites of smaller pieces. Those imaged at high-resolution show evidence for copious regolith despite the weak gravity. Most of them have one or more extraordinarily large craters, some of which are wider than the mean radius of the whole body. Such colossal impacts would not just gouge out a crater—they would break any monolithic body into pieces. In short, asteroids larger than a kilometer across may look like nuggets of hard rock but are more likely to be aggregate assemblages—or even piles of loose rubble so pervasively fragmented that no solid bedrock is left.

The rubble hypothesis, proposed decades ago by scientists, lacked evidence, until the planetologist Schumaker realized that the huge craters on the asteroid Mathilde and its very low density could only make sense together: a porous body such as a rubble pile can withstand a battering much better than an integral object. It will absorb and dissipate a large fraction of the energy of an impact; the far side might hardly feel a thing. At first, the rubble hypothesis may appear conceptually troublesome. The material strength of an asteroid is nearly zero, and the gravity is so low one is tempted to neglect that too. The truth is neither strength nor gravity can be ignored. Paltry though it may be, gravity binds a rubble pile together. And anybody who builds sandcastles knows that even loose debris can cohere. Oft-ignored details of motion begin to matter: sliding friction, chemical bonding, damping of kinetic energy, etc. We are just beginning to fathom the subtle interplay of these minuscule forces.

The size of an asteroid should determine which force dominates. One indication is the observed pattern of asteroidal rotation rates. Some collisions cause an asteroid to spin faster; others slow it down. If asteroids are monolithic rocks undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution with a statistical “tail” of very fast rotators. If nearly all asteroids are rubble piles, however, this tail would be missing, because any rubble pile spinning faster than once every two or three hours fly apart. Recently, several astronomers discovered that all but five observed asteroids obey a strict rotation limit. The exceptions are all smaller than about 150 meters in diameter, with an abrupt cutoff for asteroids larger than 200 meters. The evident conclusion—that asteroids larger than 200 meters across are rubble piles—agrees with recent computer modeling of collisions. A collision can blast a large asteroid to bits, but those bits will usually be moving slower than their mutual escape velocity (the lowest velocity that a body must have in order to escape the orbit of a planet). Over several hours, gravity will reassemble all but the fastest pieces into a rubble.

The reason that graphs of asteroid rotation rates lack the expected statistical tail associated with high rotational rates is that

QUESTION 4

Critical Reasoning: Select the best of the answer choices given.  

Over the past ten years, the population of Dismaston has grown five times as large as it was. During this time, the average income in the city has risen substantially, and a tremendous amount of capital has flowed into city. An independent audit found that, somewhat surprisingly, the number of violent felonies reported per year is now lower than it was ten years ago.

Each of the following statements below, if true, would explain the somewhat surprising finding EXCEPT:

QUESTION 5

Sentence Correction: Choose the option that best completes the underlined part of the sentence.  

Whereas both Europe and China use standard railroad gauge (1435 mm), Russia deliberately chose the wider "Russian gauge" (1520 mm) that gives greater side-to-side stability in railways cars and, more importantly, acts as a national defense, so that it would block a foreign army's supply line and preventing these bordering powers from invading by train.

QUESTION 6

Critical Reasoning: Select the best of the answer choices given.  

A luxury apartment condo recently opened up along the Biltmore’s waterfront. Within the first two months, 80% of the standard units in the first ten of the condo’s twelve stories were sold. Nonetheless, only two of the eight penthouses, all of which are located in the top two stories of the building, have sold. In order to sell the remaining six penthouses, the corporation that owns the property, should drop the rate of the penthouses by 20%.

Which of the following, if true, would argue against the proposal above?

QUESTION 7

Sentence Correction: Choose the option that best completes the underlined part of the sentence.  

Inaugurating the Romantic movement with its publication in 1798, the authors of the Lyrical Ballads were Samuel Taylor Coleridge and William Wordsworth, who would later be named Britain's Poet Laureate.

QUESTION 8

Critical Reasoning: Select the best of the answer choices given.  

Egidio's Gym has been in operation for seven years, and offers regular weekly weight training and aerobic classes, as well as occasional programs in dance and martial arts. The gym has seen a surge of new members in the past twelve months, despite keeping the same membership fee over the past three years. Of the 450 current members, more than 250 have joined in the past year. Clearly, the membership of Egidio's Gym has risen a significant amount because of its superior facilities.

Which of the following is an assumption on which the argument depends?

QUESTION 9

Sentence Correction: Choose the option that best completes the underlined part of the sentence.  

Of all the things that Washington could have done in conducting the American Revolution, nevertheless the war against the British would not have succeeded without French intervention.

QUESTION 10

Critical Reasoning: Select the best of the answer choices given.  

At Funston Stores, a salesperson's salary is comprised solely of commissions from sales. A particular salesperson's annual salary was lower in 2009 than in 2008. In both years, all of this salesperson's sales were of only one item, product X, and he made the same number of product X sales in both years. The commission percentage for all Funston salespeople has remained unchanged over the past ten years.

The information above most strongly supports which of the following?