Acceleration in an Elliptical Orbit

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Discussion Overview

The discussion revolves around the experience of acceleration for an observer in an elliptical orbit around Earth, specifically addressing whether one would feel acceleration due to the gravitational pull and the motion of the satellite.

Discussion Character

  • Conceptual clarification, Debate/contested

Main Points Raised

  • One participant suggests that an observer in an elliptical orbit would feel acceleration due to varying speeds at different points in the orbit.
  • Several participants argue that the observer would remain weightless, regardless of the orbital shape or speed, as they are in free fall along with the satellite.
  • Another participant mentions that while an external observer may perceive acceleration, the observer inside the satellite would not notice it due to being in free fall.
  • A later reply introduces the idea of tidal effects caused by variations in gravitational pull at different points in the orbit, although these effects are described as negligible.

Areas of Agreement / Disagreement

Participants generally disagree on whether the observer would feel acceleration in an elliptical orbit, with some asserting weightlessness and others questioning this based on the changing speed of the orbit.

Contextual Notes

The discussion does not resolve the nuances of how gravitational variations might affect the experience of acceleration, nor does it clarify the conditions under which the observer's experience might differ from external observations.

Geoff Pollock
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So let's say you are on an orbital satellite in an elliptical orbit around our planet Earth, meaning that the at one point in the orbit you are going faster, due to the gravitational pull of the planet. Would you feel the acceleration in space due to the shape of the orbit?
 
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No, you would still be weightless.
 
Borg said:
No, you would still be weightless.
Even with the air pressure?
 
Borg said:
No, you would still be weightless.
Because you are moving with the orbital in the orbit, that would mean you are going the same speed as it? So if it were to go faster, wouldn't you be going faster with it, in hand would you feel acceleration?
 
If an object is in free fall and you are moving in the same way (inside or near it), then you too are in free fall and weightless. From an external point of view, you may be accelerating (and even for a circular orbit, you are accelerating perpendicularly to the direction of the orbit), but since the object and the person are being accelerated by the same amount, they will not notice the acceleration.

(To be really accurate, for a large object you can get tidal effects due to the fact that gravity can vary slightly between the highest and lowest point, and you can also get tiny effects due to the mass of the object itself, but these are negligible compared with normal weight).
 

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