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Difficulty: MediumInferring Author Purpose and Intent

Early steam locomotives relied on mechanical governors to regulate engine speed under varying track loads. In a typical centrifugal governor, two weighted brass spheres spin on a central spindle driven directly by the locomotive's drive axle. As engine velocity increases, centrifugal force drives the spheres outward and upward against gravity, mechanically linkage-closing the throttle valve to reduce steam intake. Conversely, when the locomotive encounters an incline and slows down, the spheres drop inward, opening the valve to admit more steam. This mechanical feedback loop allowed operators to maintain steady boiler efficiency and prevent catastrophic wheel slippage without requiring continuous manual throttle adjustments.

Which of the following best describes the author's primary purpose in writing this passage?

  1. A
    warn locomotive operators about the dangers of catastrophic wheel slippage on steep inclines
  2. B
    argue that centrifugal governors made steam engines more powerful than modern locomotives
  3. explain how an automatic feedback mechanism regulates locomotive engine speedAnswer
  4. D
    criticize early train operators for relying excessively on manual throttle adjustments

Answer

The author's primary purpose is to explain how an automatic feedback mechanism regulates locomotive engine speed.
The author systematically outlines the physical components of the centrifugal governor and explains the mechanical process through which rotating spheres adjust the throttle valve during speed changes. Because the entire passage is structured around clarifying how this self-regulating loop operates, the primary intent is to explain the functioning of this automated speed-regulation mechanism.

Step-by-Step Solution

1
Analyze the main focus and structure of the passage
The text describes the physical components of a centrifugal governor (spindle, brass spheres, throttle linkage) and traces the physical cause-and-effect cycle that adjusts steam intake based on travel speed.
Examining the dominant content and logical organization reveals why the author composed the paragraph.
2
Determine the author's tone and rhetorical function
The passage maintains a neutral, expository tone aimed at describing how a device functions rather than persuading, warning, or criticizing.
Recognizing the expository nature of the writing distinguishes purely explanatory passages from argumentative or cautionary texts.
3
Synthesize the overarching communicative goal
The author's central aim is to inform the reader about how an automated mechanical feedback loop controls steam engine velocity under changing operating conditions.
The correct response must reflect the passage as a cohesive whole rather than an isolated detail or an unsupported inference.

Key Concept

Inferring author purpose through synthesis of main idea, rhetorical structure, and objective tone.
Estimated Time:1m 0s
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Topics

Inferring Author Purpose and Intent

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