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Heh, Anome, those edits worked out pretty well together considering we were both working pretty much blind to what the other was doing. :) -- John Owens
Oh, P.S. I'm not quite sure in my second equation, if that should be the mass of the other body, or the sum of their masses; I think it's really somewhere between the two, considering that radius for gravitational force will be from the other body, but radius of the orbit will be from the barycenter. I'll work this out soon. -- John Owens
In the atom, the speed of the orbital 1s is v=Zαc; how can I get the speed of the other orbitals?-- Daniel bg 14:23, 28 December 2005 (UTC)
I guess that under general relativity the stated speeds are not entirely correct, perhaps the article should include also the general relativistic counterparts to the classical speeds? Agge1000 15:28, 14 November 2007 (UTC)
There are some figures I couldn't understand where they come from:
| Molniya orbit||6,900 to 46,300 km||500 to 39,900 km||1.5 to 10.0 km/s||11 h 58 min||54.8 MJ/kg
Within a range of 500 to 39,900 km above the Earth, 1.5 to 10.0 km/s ? I've not yet checked all but only this due to the huge range of speed and the fact that 10 km/s is near from escape velocity from Earth surface.-- Email4mobile ( talk) 05:24, 11 July 2010 (UTC)
I don't know how the table got 0.5 km/s for a surface orbit, but the orbital velocity at 6400km is 7.89 km/s.
I have adjusted the table accordingly. — Preceding unsigned comment added by Trebudude ( talk • contribs) 01:40, 5 June 2012 (UTC)
This article has many factual errors, most either because of arbitrary and unstated assumptions or because of omission of critical qualifications. A paper last week (Oct. 2017) (sorry I don't have the citation) listed 600 families of orbits of 3-body systems (theoretically, modeled on a computer) which are far more complicated that simple ellipses. These orbits were (mostly) constrained to be in a plane (rather than in 3-d space) so form a subset of all potential closed orbits. Clearly these orbits will not have simple formulae for speed. A closed orbit is NOT an ellipse except in a simple two body (point-like) system. Satellites orbiting the Earth have velocities which vary due to the inhomogeneity of the Earths gravitational field (due to mass concentrations). This (obviously) means that the orbital speed is NOT a simple function of the larger object's mass, except as a (good) approximation. The assumption that an object can be treated as a center-of-mass point is an excellent approximation when periapsis is > 10 times the object's surface radius. Orbital speed needs to be better defined here, imho. If a satellite in a 'stable' orbit fires a bullet or rocket, then the position in the gravitational field changes little (at first) but the velocity may have changed drastically - it should distinguish between velocity and orbital velocity. General Relativity does not allow any real orbit to be stable. All so-called 'stable' orbits are only meta-stable. The orbits of the planets are predicted to be stable for the next 50,000,000 years, beyond that uncertainties in the various parameters (as well as the galactic background gravity field) allow for greater and greater potential deviation from the current orbital paths. In fact, there is some possibility that one of the inner planets will be ejected from the Solar System in the next 500 million years. In the section Mean Orbital Speed, while discussing TWO bodies, r is stated to be "the body's radius" with no regard for which body it is referring to. A rookie mistake. Finally, the lead conflates "the more massive body" with the system's barycenter. (Incidentally, the chaotic nature of orbital dynamics (over large times) is not related to the General Relativistic limitations on orbital stability - GR dissipation occurs (typically) over billions and trillions of years.) 98.21.70.161 ( talk) 18:06, 27 October 2017 (UTC)
If " Escape velocity" then "Orbital velocity" Voproshatel ( talk) 10:44, 10 July 2020 (UTC)
![]() | This article is rated Start-class on Wikipedia's
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Heh, Anome, those edits worked out pretty well together considering we were both working pretty much blind to what the other was doing. :) -- John Owens
Oh, P.S. I'm not quite sure in my second equation, if that should be the mass of the other body, or the sum of their masses; I think it's really somewhere between the two, considering that radius for gravitational force will be from the other body, but radius of the orbit will be from the barycenter. I'll work this out soon. -- John Owens
In the atom, the speed of the orbital 1s is v=Zαc; how can I get the speed of the other orbitals?-- Daniel bg 14:23, 28 December 2005 (UTC)
I guess that under general relativity the stated speeds are not entirely correct, perhaps the article should include also the general relativistic counterparts to the classical speeds? Agge1000 15:28, 14 November 2007 (UTC)
There are some figures I couldn't understand where they come from:
| Molniya orbit||6,900 to 46,300 km||500 to 39,900 km||1.5 to 10.0 km/s||11 h 58 min||54.8 MJ/kg
Within a range of 500 to 39,900 km above the Earth, 1.5 to 10.0 km/s ? I've not yet checked all but only this due to the huge range of speed and the fact that 10 km/s is near from escape velocity from Earth surface.-- Email4mobile ( talk) 05:24, 11 July 2010 (UTC)
I don't know how the table got 0.5 km/s for a surface orbit, but the orbital velocity at 6400km is 7.89 km/s.
I have adjusted the table accordingly. — Preceding unsigned comment added by Trebudude ( talk • contribs) 01:40, 5 June 2012 (UTC)
This article has many factual errors, most either because of arbitrary and unstated assumptions or because of omission of critical qualifications. A paper last week (Oct. 2017) (sorry I don't have the citation) listed 600 families of orbits of 3-body systems (theoretically, modeled on a computer) which are far more complicated that simple ellipses. These orbits were (mostly) constrained to be in a plane (rather than in 3-d space) so form a subset of all potential closed orbits. Clearly these orbits will not have simple formulae for speed. A closed orbit is NOT an ellipse except in a simple two body (point-like) system. Satellites orbiting the Earth have velocities which vary due to the inhomogeneity of the Earths gravitational field (due to mass concentrations). This (obviously) means that the orbital speed is NOT a simple function of the larger object's mass, except as a (good) approximation. The assumption that an object can be treated as a center-of-mass point is an excellent approximation when periapsis is > 10 times the object's surface radius. Orbital speed needs to be better defined here, imho. If a satellite in a 'stable' orbit fires a bullet or rocket, then the position in the gravitational field changes little (at first) but the velocity may have changed drastically - it should distinguish between velocity and orbital velocity. General Relativity does not allow any real orbit to be stable. All so-called 'stable' orbits are only meta-stable. The orbits of the planets are predicted to be stable for the next 50,000,000 years, beyond that uncertainties in the various parameters (as well as the galactic background gravity field) allow for greater and greater potential deviation from the current orbital paths. In fact, there is some possibility that one of the inner planets will be ejected from the Solar System in the next 500 million years. In the section Mean Orbital Speed, while discussing TWO bodies, r is stated to be "the body's radius" with no regard for which body it is referring to. A rookie mistake. Finally, the lead conflates "the more massive body" with the system's barycenter. (Incidentally, the chaotic nature of orbital dynamics (over large times) is not related to the General Relativistic limitations on orbital stability - GR dissipation occurs (typically) over billions and trillions of years.) 98.21.70.161 ( talk) 18:06, 27 October 2017 (UTC)
If " Escape velocity" then "Orbital velocity" Voproshatel ( talk) 10:44, 10 July 2020 (UTC)