Analogy between satelite orbit and mass oscillating through earth

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Discussion Overview

The discussion explores the analogy between the period of a satellite in orbit around the Earth and the period of a mass oscillating through a hypothetical hole in the Earth, focusing on the underlying reasons for their similarity in periods.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that the period of a satellite at surface height and a mass in simple harmonic motion through a hole in the Earth are the same, expressed mathematically as T=2 π √(R/g).
  • One participant suggests that the circular orbit can be decomposed into two simple harmonic motions, noting that the gravitational force in each dimension is proportional to the position along that dimension.
  • Another participant points out that the equivalence of the periods holds only under the assumption of uniform Earth density, indicating that this assumption may not be entirely correct.
  • Participants express interest in exploring alternative approaches to explain the analogy further, acknowledging the complexity of the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus; while some agree on the similarity of the periods under certain assumptions, others challenge the validity of those assumptions, particularly regarding Earth's density.

Contextual Notes

The discussion highlights the assumption of uniform density for the Earth as a critical factor in the analogy, which remains unresolved. The implications of non-uniform density are not fully explored.

Ezio3.1415
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The period of a satellite revolving around the Earth earth at surface height is equal to the period of any mass thrown through a hole of the earth(which gains a simple harmonic motion)...

It seemed really interesting to me...

Why both of these periods are same?

T=2 π √(R/g)
 
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Ezio3.1415 said:
Why both of these periods are same?
You can decompose the circular orbit into two simple harmonic motions in two dimensions. The gravitational force component in each dimension is proportional to the position along that dimension. The same proportional relationship exists along a radial line in a uniform mass sphere.
 
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Ezio3.1415 said:
The period of a satellite revolving around the Earth earth at surface height is equal to the period of any mass thrown through a hole of the earth(which gains a simple harmonic motion)...

It seemed really interesting to me...

Why both of these periods are same?

T=2 π √(R/g)

That's only true if you assume the Earth's density is uniform. That's not quite correct.
 
AT Yes,but we are doing another analogy to explain this analogy... I thought of it at first but assumed their could be another approach to explain this incident... It just seems so interesting to me...

Dauto Yes... That's why we have to assume that the Earth is a uniform mass sphere...
 

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