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A meteor stream is composed of dust particles that have been

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A meteor stream is composed of dust particles that have been [#permalink] New post 13 Mar 2013, 06:46
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A meteor stream is composed of dust particles that have been ejected from a parent comet at a variety of velocities. These particles follow the same orbit as the parent comet, but due to their differing velocities they slowly gain on or fall behind the disintegrating comet until a shroud of dust surrounds the entire cometary orbit. Astronomers have hypothesized that a meteor stream should broaden with time as the dust particles' individual orbits are perturbed by planetary gravitational fields. A recent computer-modeling experiment tested this hypothesis by tracking the influence of planetary gravitation over a projected 5,000-year period on the positions of a group of hypothetical dust particles. In the model,
the particles were randomly distributed throughout a computer simulation of the orbit of an actual meteor stream, the Geminid. The researcher found, as expected, that the computer-model stream broadened with time. Conventional theories, however, predicted that the distribution of particles would be increasingly dense toward the center of a meteor
stream. Surprisingly, the computer-model meteor stream gradually came to resemble a thick-walled, hollow pipe.

Whenever the Earth passes through a meteor stream, a meteor shower occurs. Moving at a little over 1,500,000 miles per day around its orbit, the Earth would take, on average, just over a day to cross the hollow, computer-model Geminid stream if the stream were 5,000 years old. Two brief periods of peak meteor activity during the shower would be observed, one as the Earth entered the thick-walled "pipe" and one as it exited. There is no reason why the Earth should always pass through the stream's exact center, so the time interval between the two bursts of activity would vary from one year to the next.

Has the predicted twin-peaked activity been observed for the actual yearly Geminid meteor shower? The Geminid data between 1970 and 1979 shows just such a bifurcation, a secondary burst of meteor activity being clearly visible at an average of 19 hours (1,200,000 miles) after the first burst. The time intervals between the bursts suggest the actual
Geminid stream is about 3,000 years old.
Q. It can be inferred from the passage that which of the following would most probably be observed during the Earth's passage through a meteor stream if the conventional theories mentioned in line 18 were correct?
(A) Meteor activity would gradually increase to a single, intense peak, and then gradually decline.
(B) Meteor activity would be steady throughout the period of the meteor shower.
(C) Meteor activity would rise to a peak at the beginning and at the end of the meteor shower.
(D) Random bursts of very high meteor activity would be interspersed with periods of very little activity.
(E) In years in which the Earth passed through only the outer areas of a meteor stream, meteor activity would be absent.
[Reveal] Spoiler:
A


The passage suggests that which of the following is a prediction concerning meteor streams that can be derived from both the conventional theories mentioned in line 18 and the new computer-derived theory?
(A) Dust particles in a meteor stream will usually be distributed evenly throughout any cross section of the stream.
(B) The orbits of most meteor streams should cross the orbit of the Earth at some point and give rise to a meteor shower.
(C) Over time the distribution of dust in a meteor stream will usually become denser at the outside edges of the stream than at the center.
(D) Meteor showers caused by older meteor streams should be, on average, longer in duration than those caused by very young meteor streams.
(E) The individual dust particles in older meteor streams should be, on average, smaller than those that compose younger meteor streams.
[Reveal] Spoiler:
D



Please explain how to answer these questions.
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Re: A meteor stream is composed of dust particles that have been [#permalink] New post 13 Mar 2013, 10:57
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I changed the tag to 700 because this was really tough and comes from OG 11th edition

Q. It can be inferred from the passage that which of the
following would most probably be observed during
the Earth's passage through a meteor stream if the
conventional theories mentioned in line 18 were
correct?

(A) Meteor activity would gradually increase to a
single, intense peak, and then gradually decline.

This is stated in the passage "Conventional theories, however, predicted
that the distribution of particles would be
increasingly dense toward the center of a meteor
stream.


(B) Meteor activity would be steady throughout the
period of the meteor shower.

this contraddict A

(C) Meteor activity would rise to a peak at the
beginning and at the end of the meteor shower.

No is false

(D) Random bursts of very high meteor activity
would be interspersed with periods of very little
activity.

I didn't see anything about that

(E) In years in which the Earth passed through only
the outer areas of a meteor stream, meteor
activity would be absent.

I didn't see something about "absent"

The second one was even tough

The passage suggests that which of the following is a
prediction concerning meteor streams that can be
derived from both the conventional theories
mentioned in line 18 and the new computer-derived
theory?
(A) Dust particles in a meteor stream will usually be
distributed evenly throughout any cross section
of the stream.

Dust particles is not the poin of theories

(B) The orbits of most meteor streams should cross
the orbit of the Earth at some point and give rise
to a meteor shower.

neither the orbit

(C) Over time the distribution of dust in a meteor
stream will usually become denser at the outside
edges of the stream than at the center.

We know that is not true

D) Meteor showers caused by older meteor streams
should be, on average, longer in duration than those caused by very young meteor streams.

This is the line 8 " Astronomers have
hypothesized that a meteor stream should broaden
with time as the dust particles' individual orbits are
perturbed by planetary gravitational fields.
The older is the meteor, more broaden is its stream, viceversa is a younger comet


(E) The individual dust particles in older meteor
streams should be, on average, smaller than those
that compose younger meteor streams.

Average is not the point of this inference question
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Re: A meteor stream is composed of dust particles that have been [#permalink] New post 07 Mar 2014, 03:28
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Re: A meteor stream is composed of dust particles that have been [#permalink] New post 16 Mar 2013, 05:36
carcass wrote:
I changed the tag to 700 because this was really tough and comes from OG 11th edition

Q. It can be inferred from the passage that which of the
following would most probably be observed during
the Earth's passage through a meteor stream if the
conventional theories mentioned in line 18 were
correct?

(A) Meteor activity would gradually increase to a
single, intense peak, and then gradually decline.

This is stated in the passage "Conventional theories, however, predicted
that the distribution of particles would be
increasingly dense toward the center of a meteor
stream.


(B) Meteor activity would be steady throughout the
period of the meteor shower.

this contraddict A

(C) Meteor activity would rise to a peak at the
beginning and at the end of the meteor shower.

No is false

(D) Random bursts of very high meteor activity
would be interspersed with periods of very little
activity.

I didn't see anything about that

(E) In years in which the Earth passed through only
the outer areas of a meteor stream, meteor
activity would be absent.

I didn't see something about "absent"

The second one was even tough

The passage suggests that which of the following is a
prediction concerning meteor streams that can be
derived from both the conventional theories
mentioned in line 18 and the new computer-derived
theory?
(A) Dust particles in a meteor stream will usually be
distributed evenly throughout any cross section
of the stream.

Dust particles is not the poin of theories

(B) The orbits of most meteor streams should cross
the orbit of the Earth at some point and give rise
to a meteor shower.

neither the orbit

(C) Over time the distribution of dust in a meteor
stream will usually become denser at the outside
edges of the stream than at the center.

We know that is not true

D) Meteor showers caused by older meteor streams
should be, on average, longer in duration than those caused by very young meteor streams.

This is the line 8 " Astronomers have
hypothesized that a meteor stream should broaden
with time as the dust particles' individual orbits are
perturbed by planetary gravitational fields.
The older is the meteor, more broaden is its stream, viceversa is a younger comet


(E) The individual dust particles in older meteor
streams should be, on average, smaller than those
that compose younger meteor streams.

Average is not the point of this inference question


Perfect explanation. Though i tried to apply my so called "Skimming techniques", i got both the answers wrong. Sometimes, you have to just read the passage in detail! Please do let me know if you followed any other technique to "read" the passage
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Re: A meteor stream is composed of dust particles that have been [#permalink] New post 16 Mar 2013, 06:39
If you can distinguish what is the difference between the conventional and computer theory, job is done.
Conventional theories predicted that the distribution of particles would be increasingly dense toward the center of a meteor stream.
Computer theory opposes the same and that is what passage is focusing on. This theory says that the concentration wont be dense but will broaden with time.

To answer both the question, this understanding is enough. I skimmed most of the parts of the passage and was able to get both right.
If we can understand what author is focusing on, job is done.
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Re: A meteor stream is composed of dust particles that have been   [#permalink] 16 Mar 2013, 06:39
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