Comprehension

From a vantage point in space, an observer could see that the Earth is engaged in a variety of motions. First, there is its rotation on its own axis, causing the alternation of day and night. This rotation, however, is not altogether steady. Primarily because of the moon’s gravitational action, the Earth’s axis wobbles like that of an ill-spun top. In this motion, called ‘precession’, the North and South Poles each traces out the base of a cone in space, completing a circle every 25,800 years. In addition, as the Sun and the Moon change their positions with respect to the Earth, their changing gravitational effects result in a slight ‘nodding’ of the earth’s axis, called ‘mutation’, which is superimposed on precession. The Earth completes one of these ‘nods’ every 18.6 years.
The earth also, of course, revolves round the Sun, in a 6-million mile journey that takes 365.25 days. The shape of this orbit is an ellipse, but it is not the center of the Earth that follows the elliptical path. Earth and Moon behave like an asymmetrical dumb-bell, and it is the center of mass of this dumb-bell that traces the ellipse around the sun. The center of the Earth-Moon mass lies about 3000 miles away from the center of the Earth, and the Earth thus moves in an S-curve that crosses and re-crosses its orbital path. Then too, the Earth accompanies the sun in the sun’s movements: first, through its local star cloud, and second, in a great sweep around the hub of its galaxy, the Milky Way that takes 200 million years to complete.

Question: 1

The passage is most likely directed towards an audience of

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When determining the audience, consider the vocabulary level, use of analogies, and the assumed background knowledge in the passage.
Updated On: Aug 7, 2025
  • geologists.
  • astronauts.
  • meteorologists interested in weather prediction.
  • person with little technical knowledge of astronomy.
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The Correct Option is D

Solution and Explanation

The passage uses clear, non-technical language to explain complex motions of the Earth, such as precession, mutation, and revolution, using analogies like an “ill-spun top” and “dumb-bell.” This indicates the intended audience is general readers with little technical knowledge of astronomy, rather than specialists.
- Options (a), (b), and (c) imply a technical or professional audience, but the passage does not use highly specialized jargon or focus on those fields.
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Question: 2

Which of the following best describes the main subject of the passage?

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Main subject questions should be answered with the most inclusive option that covers the whole passage.
Updated On: Aug 7, 2025
  • The various types of the Earth’s motions
  • Past changes in the Earth’s position
  • The moon gravitational effect on the earth
  • Oddities of the Earth’s rotation of its axis.
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The Correct Option is A

Solution and Explanation

The passage describes multiple motions: rotation on its axis, precession, mutation, revolution around the Sun, movement of the Earth-Moon system, and the Sun’s motion through space. This makes “various types of the Earth’s motions” the most accurate description of the main subject.
- Option (b) is too narrow and historical.
- Option (c) focuses only on one cause.
- Option (d) addresses only one type of motion, not all discussed.
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Question: 3

The passage indicates that a single cycle of which of the following motions is completed in the shortest period of time?

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For time-comparison questions, identify the period stated for each motion and pick the smallest.
Updated On: Aug 7, 2025
  • Mutation.
  • Precession.
  • The Earth’s rotation on its axis.
  • The movement of the dumb-bell formed by the center of mass of Earth-Moon.
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The Correct Option is C

Solution and Explanation

The Earth’s rotation on its axis takes approximately 24 hours, making it the shortest cycle among the motions described.
- Mutation takes 18.6 years per cycle.
- Precession takes 25,800 years.
- The Earth-Moon dumb-bell movement around the Sun takes one year.
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Question: 4

Which of the following techniques does the author use in order to make the descriptions of motion clear? I. Comparison with familiar objects.
II. Reference of geometric forms.
III. Allusions to the works of other authors.

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Look for analogies and shapes mentioned in descriptive passages — they help identify techniques used for clarity.
Updated On: Aug 7, 2025
  • I only
  • II only
  • I and II only
  • II and III only
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The Correct Option is C

Solution and Explanation

The author compares Earth’s axial wobble to an “ill-spun top” (I) and refers to geometric forms like a cone for precession (II). There are no allusions to other authors (III). Therefore, I and II are correct.
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