Originally, scientists predicted small asteroids to be hard and rocky,

Question

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 pile.   1 
  1. 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?

A. Asteroids actually contain a significant amount of regolith despite the force of weak gravity. 
B. Because of a great degree of fragmentation such an asteroid would have to have a solid bedrock. 
C. Such a crater would most probably result from a series of small impacts over a period of time. 
D. Most asteroids are held together by a series of forces that are often unstable. 
E. This claim would constitute evidence that the asteroid is not monolithic.

2 
 2. The primary purpose of the passage is to

A. refute an unconventional theory regarding asteroid collisions 
B. express doubt regarding the validity of evidence offered up by several notable astronomers 
C. explain how earlier evidence used to describe an aspect of asteroids was misleading 
D. explore common features of an asteroid in order to provide support for a theory 
E. discuss how one explanation of an astronomical phenomenon is most likely correct

3 
 3. The example of the sandcastle (in the second paragraph) serves to

A. invalidate Schumaker's initial observation 
B. offer an alternative hypothesis for an observed phenomenon 
C. describe a condition in which the typical laws of the universe do not obtain 
D. provide support for the rubble-pile hypothesis 
E. present as instance in which gravity has little effect

4 
 4. The reason that graphs of asteroid rotation rates lack the expected statistical tail associated with high rotational rates is that

A.the greater the speed in which an asteroid spins the more likely it is to cohere 
B. the weak forces in asteroids displaying such a high rotational rate would not be able to prevent the asteroid from falling apart 
C. asteroids are not being subjected to a uniform distribution of random collisions 
D. most monolithic asteroids, upon colliding with other asteroids, are able to sustain such a high rate of rotation 
E. for the most part, the asteroids surveyed were less than 150 meters in diameter and thus far less likely to be rubble-piles, which are better able to sustain the impact from collisions

5 
 5. Schumaker originally conceived of the rubble hypothesis because he surmised that

A a solid body is able to withstand impacts if it has a diameter greater than 1 km
B an object with low density can reassemble more easily after a major impact
C an asteroid that is held loosely together is better able to withstand substantial impacts
D the asteroid Matilda lacked the regolith common to asteroids of a similar size
E forces holding together large meteors were too weak to deal with major collisions

6 
 6. Scientists originally believed that asteroids lacked regolith because

A a sizeable enough impact would cause all accumulated surface material to become dislodged
B the gravitational forces of asteroids were too weak to hold any aggregation of matter together
C computer models had shown that loose pieces of rock tend to come dislodged from even the slightest impact
D regolith was absent from smaller planets lacking an atmosphere
E the velocity of asteroids was so great as to cause any loose matter to easily float off into space

srishti201996 · Answer

good rc!

Can i get an expert explanation for first and last question?
i got first question right by POE. Want to know the logic.

And last one! option wise POE!

Thanks

Talayva · Answer

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 . This statement proves Option B for last question

pikolo2510 · Answer

the author says that for if the asteroid were monolithic, then any huge collision would break the monolithic rock into o many small pieces ( nuggets ). But what we see is the opposite i.e. inspite of a big collision, we see the asteroid with a huge crater and this is only possible if the steroid is made up of smaller fragments of pieces

Hence answer for question 1 should be option E

aragonn · Answer

Official Explanation Q4

Answer: (B)

According to the passage, “…any rubble spinning faster…fly apart.” Therefore (B).

(A) is wrong because the passage says that rubble-piles will fall apart after spinning faster than a certain rate.

(C) is not supported by the passage.

(D) can be inferred from information in the passage, but it does not answer the question.

(E) is incorrect because the passage mentions that most of the asteroids were rubble piles.

aragonn · Answer

Official Explanation for Q1

This is a difficult question, mainly because the right answer doesn’t jump out at you. The passage says that an asteroid with a crater larger than its radius is not a monolithic body. In other words, the asteroid is a bunch of rocks held together by the weak forces of the asteroid. So if a scientist comes along (as the question has it) and tells the author of the passage that there is an asteroid with a crater greater than half of its body, the author of the passage would say that this evidence, not of an impact, but that the body is not monolithic. Thus the best answer, though not the perfect answer, is (E).

(A) is tempting because it is supported by the first paragraph. But it is not directly related to the claim of the other scientist (which is about a large crater).

(B) is not supported because the passage specifically says that any large asteroid with a large crater is very likely to be an aggregation (or an accumulation) or rocks (“Such colossal impacts…bedrock is left.”). Therefore, the asteroid would not have a solid bedrock, but would be “pervasively fragmented.”

(C) is not supported by the passage.

(D) is wrong because weak forces, while mentioned, aren’t described as unstable.

aragonn · Answer

An extra question not mentioned above  workout

According to the passage, which of the following best accounts for the fact that the rubble pile hypothesis is, at least initially, “conceptually troublesome”?

A. Not all the forces holding together an accumulation of rocks are equal in their intensity.
B. Some asteroids will come apart if they spin too fast, whereas others will be able to remain intact.
C. Depending on the size of an asteroid, the outcome from an impact can be drastically different.
D. Asteroid fragments often move slower than the escape velocity thereby making disintegration unlikely.
E. Forces that are so small as to be almost negligible are strong enough, when working together, to hold a rubble pile together.

aragonn · Answer

Official Explanation for extra question

The reason the rubble-pile is conceptually troubling is one would expect the rubble-pile to fall apart. Instead, it is held together by these weak forces, which, surprisingly, are able to hold the asteroid together. The reason is the weak forces work together to keep the asteroid from disintegrating. This matches up best with (E).

(A) is wrong because while weak forces are mentioned, the differences between weak forces is not.

(B) is wrong. Though the passage talks about some rubble-piles spinning too fast, this phenomenon does not relate to the part of the passage that talks about “conceptually troublesome.”

(C) is true at a commonsense level, but it has nothing to do with why the author of the passage says that the rubble-pile may be “conceptually troublesome.”

(D) touches on a part of the passage that does not relate to “conceptually troublesome.”

aragonn · Answer

Official Explanation for Q6

Answer: (B)

According to the first paragraph, “Originally, scientists…expected to escape their weak gravity.” This matches up best with (B).

(A), while it sounds sensible, doesn’t directly answer the question. According to the passage, regolith was expected to float off into space because the weak force because it “was expected to escape <asteroids> weak gravity.” We are not focused, in this question, on the entire asteroid coming apart.

(C) is wrong because the computer models do not refer to what scientists originally believed.

(D) and (E) are not supported by the passage.

aragonn · Answer

Official Explanation for Q5 Schumaker arrived at the conclusion, “a rubble pile can withstand a battering much better than an integral object.” This matches up best with (C).

(A) is tempting but the passage never said that larger asteroids (1 km and above) are more likely not to fall apart than asteroids less than 1 km. It does mention solid body asteroids, but these are much smaller (150 meters).

(B) is wrong because the passage is focused on rubble piles not falling apart not on solid bodies not falling apart (it is implied that solid bodies disintegrate because they cannot withstand the impact of major collisions).

(D) is wrong because regolith is not mentioned in conjunction with Matilda and Schumaker’s hypothesis.

(E) is wrong because Schumaker is dealing with “weak forces”, not forces that are too weak.

AdityaHongunti · Answer

mikemcgarry

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.

My understanding= ast - assemblage of loose rubble - reasoning - models show regolith - large craters on asts- implications of that>> if ast monolithic a different phenonomenon would be witnessed but such scenario isnt so- to summarise- ast is more of regolith bound together.

the main pt. of the para is to sum up to the composition of ast.

Q1- large crater is the result of an impact >> then the ast is likely to be what the models are showing>> increasing the likelihood of the ast being aggregate assemblage

what i thot of option E is that though it is deducible but in the larger picture it is playing the role of supporting the overall position that asteriods are aggregate assemblage.

My requests-

1. my reasoning,should it be wrong, is incorrect for what reason .
2. in the ans choice is the "significant amount of regolith " wrongly worded as the word "significant " is not explicitly mentioned
3. why is my reasoing wrong and why is the apparent correct answer correct

everyone is welcome to resolve my doubts but i request you to be thorough in your reasoning or else it wouldnt make any difference as already the OE has been posted. I request a thorough explanation

jawele · Answer

1. 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?  Relevant text: 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. 
A. Asteroids actually contain a significant amount of regolith despite the force of weak gravity. 
B. Because of a great degree of fragmentation such an asteroid  would have to have a solid bedrock . 
C. Such a crater would most probably result from a  series of small impacts over a period of time . 
D. Most asteroids are held together by a series of forces that are often  unstable . 
E. This claim would constitute evidence that the asteroid is not monolithic.  correct

2. The primary purpose of the passage is to 
A. refute an  unconventional  theory regarding asteroid  collisions  
B. express  doubt regarding the validity of evidence  offered up by several  notable  astronomers 
C. explain how  earlier evidence  used to describe an aspect of asteroids was  misleading  
D. explore  common features  of an asteroid in order to provide support for a theory 
E. discuss how one explanation of an astronomical phenomenon is most likely correct  correct

3. The example of the sandcastle (in the second paragraph) serves to 
A.  invalidate  Schumaker's initial observation 
B.  offer  an alternative hypothesis for an observed phenomenon  it illustrates rather than offers one 
C. describe a condition in which the  typical laws of the universe do not obtain  
D. provide support for the rubble-pile hypothesis  correct 
E. present as instance in which  gravity has little effect

4. The reason that graphs of asteroid rotation rates lack the expected statistical tail associated with high rotational rates is that  Relevant text: 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. 
A.the  greater the speed  in which an asteroid spins the  more likely it is to cohere  
B. the weak forces in asteroids displaying such a high rotational rate would not be able to prevent the asteroid from falling apart  correct 
C. asteroids are not being subjected to a uniform distribution of random collisions 
D.  most  monolithic asteroids, upon colliding with other asteroids, are able to sustain such a high rate of rotation 
E.  for the most part, the asteroids surveyed were less than 150 meters in diameter  and thus far less likely to be rubble-piles, which are better able to sustain the impact from collisions  inaccurate

5. Schumaker originally conceived of the rubble hypothesis because he surmised that  Relevant text: 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.  
A a  solid body  is able to withstand impacts if it has a  diameter greater than 1 km 
B an object with low  density  can reassemble more  easily  after a major impact
C an asteroid that is held loosely together is better able to withstand substantial impacts  correct 
D the asteroid Matilda lacked the regolith  common to asteroids  of a similar size
E  forces  holding together large meteors  were too weak  to deal with major collisions

6. Scientists originally believed that asteroids lacked regolith because  Relevant text: 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.  
A a sizeable enough impact would cause all accumulated surface material to become dislodged  fails to address the gravity 
B the gravitational forces of asteroids were too weak to hold any aggregation of matter together  correct 
C  computer models  had shown that loose pieces of rock tend to come dislodged from even the slightest impact
D regolith was absent from smaller  planets  lacking an atmosphere
E the  velocity  of asteroids was so great as to cause any loose matter to easily float off into space

ankitamundhra28 · Answer

12 minutes for the passage and all correct answers, which i feel is pretty okay considering there were 6 questions.
I doubt this is a 700 level RC.
I have seen the RCs of MGMAT & Manhattanprep mocks and this is nowhere near the difficulty level of those.

Hope to get such passages on D-day!!! :D

ag1991 · Answer

What difficulty level is this passage? I read it 4-5 times and still had difficulty grasping it and when I started to attempt the questions, I didn't even know what the question meant. I am afraid I would have to guess the answers for all these questions. What is the trick to solving such convoluted passages?

Sajjad1994 · Answer

The difficulty level is as follow:

#1. 700 
#2. 700
#3. 550
#4. 650
#5. 650
#6. 600

Overall: 650

VerbalBot · Answer

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Originally, scientists predicted small asteroids to be hard and rocky,

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GMAT Reading Comprehension (RC) Questions

Originally, scientists predicted small asteroids to be hard and rocky,

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