A recent ball-catching experiment conducted in space by astronauts on

Sorry for the delay

Sometimes I have too much emails in my inbox from gmatclub that some escapes me.

thanks for PVT. here there are the solution along the explanations.

Thanks

1.
The passage states the following about the astronauts' arm movements: "While the
astronauts did not adapt to the conditions in space for some time, by day 15 of the
experiment, the amplitude of the premature arm movements decreased and a new
well-timed arm movement immediately preceded the catch." The question asks for
an inference about what was occurring BEFORE day 15, during the period when the
astronauts were having trouble adjusting to the conditions in space. This inference
should be provable from the passage.

(A) The passage does not discuss the height of the astronauts arm movements.
While the passage mentions the amplitude, or abundance, of the premature arm
movements, it never mentions the altitude, or height, of those movements.

(B) The astronauts arm movements tended to be premature, or too early, during the
first two weeks of the experiment. This is the exact opposite of the inference in this
answer choice – that the astronauts adjusted their arms at the latest possible time.

(C) Little can be inferred about the relative number of arm movements made by the
astronauts in attempting to catch the ball. If anything, the fact that the astronauts
tended to move their arms prematurely might suggest that they made a greater
number of arm movements than they would have on earth.

(D) The passage mentions that by day 15 "a new well-timed arm movement
immediately preceded the catch." One might infer that this new arm movement was
absent during the previous two weeks. However, this does not mean that the
astronauts' arms were stationary for a full two seconds immediately preceding the
catch. No mention of specific time frames is ever made or hinted to in the passage.

(E) CORRECT. The astronauts moved their arms prematurely during the first two
weeks of the experiment. This means that they adjusted their arms sooner than was
necessary to catch the ball.

2.
The question asks for some information that would support the theory that the brain
has built-in knowledge of gravity. The correct answer choice must demonstrate that
gravity is not a principle that individuals learn about exclusively through observation
and experience, but instead that they are born with some instinctual understanding
of downward acceleration.
(A) An individual's hand-eye coordination generally requires some understanding of
gravity. For example, one's ability to see a thrown ball and then catch it is, at least in
some measure, dependent on the individual's understanding that gravity will be
pulling the ball downward. However, the fact that this coordination tends to diminish
as one gets older suggests nothing as to whether the brain has built-in knowledge of
gravity.

(B) CORRECT. The fact that infants placed above the ground fear falling without
ever having experienced it before strongly suggests that their brains are hard-wired
with some knowledge of gravity. If the infants did not understand the tendency of
objects, including themselves, to accelerate down toward the earth, they would have
no reason to become fearful when placed on a glass tabletop.

(C) The disorientation that astronauts experience after departing earth for space may
in some way be impacted by the difference between gravitational conditions on earth
and in space. However, this has no bearing on whether the brain has built-in
knowledge of gravity or not.

(D) The fact that most young children can learn to catch a ball suggests only that
they can learn to anticipate the effect of gravitational forces on a ball. It suggests
nothing about whether these children understand these forces a priori.

(E) The fact that this is counter-intuitive to most individuals, far from supporting the
notion that the brain has built-in knowledge of gravity, actually suggests that people
don't fully understand how gravity truly works.

3.
The first paragraph of the passage states that the ball-catching space experiment
suggests that “the brain can adapt to environments in which the force of downward
acceleration is less pronounced than it is on earth.” Since the passage compares
conditions in space to conditions on earth, the “environment” referred to here must
be that in space. Thus, while gravity exists in space, it is less pronounced than on
earth.

(A) The passage implies that gravity is “less pronounced” in space, not that it does
not exist at all.

(B) According to the passage, the “astronauts’ anticipation of the ball’s motion was
slightly off.” The fact that the anticipation was “slightly” off, as opposed to completely
off, implies that, contrary to this answer choice, humans do experience some, albeit
less, gravity in space than they do on earth.

(C) CORRECT. The opening paragraph uses the phrase “less pronounced” to
describe the difference in gravitational conditions in space and on earth. Moreover,
the passage states that astronauts had “premature arm movements” when
attempting to catch balls in space, implying to researchers that the astronauts were
faced with a weaker downward acceleration in space than they had anticipated
based on their brains' earth-centric wiring.
(D) No text in the passage implies that the force of gravity is the same on earth as in
space. On the contrary, the entire experiment provides evidence that contradicts this
assertion.

(E) The passage does not mention any weightless sensation experienced by
humans in space.


4.
The last paragraph comments on the potential “practical benefits” of the research
experiment described earlier in the passage. In so doing, it presents the broad
implications of the ball-catching space experiment which is explained with careful
detail in earlier paragraphs.

(A) The last paragraph does not provide any alternate point of view to McIntyre’s
analysis of the ball-catching experiment.

(B) Although the final paragraph builds on the main points of the previous
paragraphs, it does not summarize them in any way. The earlier paragraphs provide
a description and analysis of the ball-catching experiment. In contrast, the final
paragraph comments on the practical implications of the experiment.

(C) There is no ambiguous issue raised in the second paragraph.

(D) CORRECT. The earlier paragraphs of the passage have a narrow focus in that
they are chiefly concerned with a specific description and interpretation of the ball-
catching experiment. The final paragraph opens up this focus by commenting on the
broader implications of the experiment, such as the practical benefits this new
understanding might have on safe space travel and on potential treatment for certain
coordination problems.

(E) No specific researchers are mentioned in the final paragraph. Moreover, although
the final paragraph comments on potential areas for further research, no challenge is
explicitly presented to scientists.


5.
The first paragraph of the passage presents two conclusions drawn from the ball-
catching experiment: (1) "the brain contains an internal model of gravity that is both
powerful and persistent and (2) "the brain can adapt" to environments where gravity
is less pronounced than it is on earth. The second paragraph describes the
experiment in-depth and demonstrates how scientists arrived at the first conclusion.
The third paragraph demonstrates how scientists came to the second conclusion.
The fourth and final paragraph identifies some practical benefits that the experiment
might have. The correct answer choice must relate to most of the four paragraphs
and, since this is a long passage, it must be closely tied to the all-important first
paragraph.
(A) CORRECT. This choice directly relates to the first paragraph, which presents the
experiment's conclusions, and to the second and third paragraphs, which describe
the experiment in-depth.

(B) The practical applications of the experiment are described only in the fourth
paragraph of the passage. This does not represent the primary purpose of the
passage.

(C) The passage does not mention any misunderstanding about how the brain
functions. Instead, it presents new insight about the brain's internal workings.

(D) While gravity is mentioned in the passage, there is no description of how gravity
works. Moreover, the passage is focused on responses to different gravitational
forces, not on gravity itself.

(E) The passage describes only one experiment in space; as such, it never alludes
to space experiments in general. Additionally, while the passage implies that the ball-
catching experiment was beneficial, it never explicitly outlines the benefits of
conducting experiments in space.


6.
The passage describes certain explicit features of the brain's built-in understanding
of gravity. The correct answer choice must be directly provable using the specific
language contained in the passage.

(A) The brain's built in-understanding of gravity is, according to the passage, "hard-
wired from an earth-centric perspective," not a space-centric one.

(B) CORRECT. One of the major outcomes of the experiment described in the
passage is that "the brain can adapt to environments in which the force of downward
acceleration is less pronounced than it is on earth."

(C) According to the passage, the neuroscientists concluded that "the brain contains
an internal model of gravity that is both powerful and persistent." To describe the
brain's understanding of gravity as "fleeting" directly contradicts the word
"persistent."

(D) According to the passage, the neuroscientists concluded that "the brain contains
an internal model of gravity that is both powerful and persistent." To describe the
brain's understanding of gravity as "weak" directly contradicts the word "powerful."

(E) The passage never describes the brain's built-in understanding of gravity as
"evolving." While scientists' understanding of the brain's hard-wiring may evolve,
there is nothing in the passage that suggests that the hard-wiring itself is evolving.