Revolution under the influence of a central force

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Discussion Overview

The discussion revolves around the effects of the absence of Earth's rotation on the perception of day and night, particularly in the context of Earth's revolution around the Sun. Participants explore the implications of central forces and reference frames in understanding these phenomena.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants argue that without Earth's rotation, a point on its surface would not change its position relative to the Sun, while others contend that it could change relative to other reference frames, such as distant stars.
  • One participant suggests a thought experiment involving a pebble tied to a string to illustrate the concept of rotational motion and its effects on position.
  • Another participant proposes using a laser ring gyroscope to measure Earth's rotational velocity, indicating that a change in this velocity would affect the day-night cycle.
  • Concerns are raised about the application of forces and torques in these scenarios, particularly regarding how forces act on the center of mass versus points on the surface.
  • There is a discussion about the importance of reference frames, with some participants emphasizing the fixed stars as a familiar frame for analysis.

Areas of Agreement / Disagreement

Participants express differing views on the implications of Earth's rotation and revolution, with no consensus reached on the correctness of the arguments presented. The discussion remains unresolved, with multiple competing perspectives on the topic.

Contextual Notes

Participants highlight the complexity of the concepts involved, including the roles of torque and reference frames, and the potential misunderstandings that arise from these discussions.

  • #31
A.T. said:
Yeah, I got that. Just though that the concept of negative days might be confusing.
You are right. There is a separate formula for retrograde rotation, which gives positive days. But I would rather use one formula with negative numbers than two formulas with positive numbers.
 

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