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Re: Newton not entirely right

From Sylvia Else <sylvia@not.at.this.address>
Newsgroups sci.physics.relativity
Subject Re: Newton not entirely right
Date 2015-09-29 16:32 +1000
Message-ID <d6upkfF3pqhU1@mid.individual.net> (permalink)
References <a3e5b94c-79e7-40e3-bae5-014a28b35f30@googlegroups.com> <mubooe$44b$2@speranza.aioe.org> <e25300df-e1fd-4a14-ba76-693f5cc64557@googlegroups.com>

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On 29/09/2015 11:32 AM, Peter Riedt wrote:
> On Tuesday, September 29, 2015 at 12:09:54 AM UTC+8, Odd Bodkin
> wrote:
>> On 9/28/2015 1:26 AM, Peter Riedt wrote:
>>>
>>> Newton's law of universal gravitation is incomplete. It considers
>>> gravity a force of attraction but it does not account for
>>> celestial bodies that cannot complete the descent to their
>>> primary.
>>
>> Orbiting bodies would not follow ellipses if they weren't
>> attracted. They would travel in straight lines. Attraction doesn't
>> require that the two bodies end up in contact. What makes you think
>> they would?
>>
>>
>> -- Odd Bodkin --- maker of fine toys, tools, tables
>
> It would be nice if there was a precise explanation and formula at
> what point a descent changes into an ellipse instead of an impact and
> how bodies of different mass acquire the different velocities
> required to keep them at different distances from the sun.
>

There is no such point. The motion is always an ellipse. If the ellipse 
intercepts the surface of the primary, then there is an impact. 
Otherwise there isn't.

As for acquiring velocities, if you take a object, position it at some 
random place relative to a primary and give it an initial random 
velocity in some random direction, it immediately starts following an 
elliptical orbit[*].

Sylvia.

[*] Or a hyperbolic non-orbit if you happen to have given it escape 
velocity.

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Thread

Newton not entirely right Peter Riedt <riedt1@yahoo.co.uk> - 2015-09-27 23:26 -0700
  Re: Newton not entirely right Dirk Van de moortel <dirkvandemoortel@hotspam.not> - 2015-09-28 16:00 +0200
    Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-28 11:49 -0400
      Re: Newton not entirely right mlwozniak@wp.pl - 2015-09-29 01:13 -0700
        Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-29 14:48 -0400
          Re: Newton not entirely right pnalsing@gmail.com - 2015-09-29 13:19 -0700
            Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-29 16:56 -0400
              Re: Newton not entirely right pnalsing@gmail.com - 2015-09-29 14:06 -0700
                Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-29 17:43 -0400
                Re: Newton not entirely right Kent Beeler <kenbee@jefffast.au> - 2015-09-29 21:59 +0000
                Re: Newton not entirely right pnalsing@gmail.com - 2015-09-29 15:39 -0700
                Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-29 19:44 -0400
                Re: Newton not entirely right pnalsing@gmail.com - 2015-09-29 19:37 -0700
                Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-30 00:27 -0400
                Re: Newton not entirely right pnalsing@gmail.com - 2015-09-29 21:42 -0700
                Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-30 02:57 -0400
                Re: Newton not entirely right pnalsing@gmail.com - 2015-09-29 21:44 -0700
                Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-30 02:58 -0400
                Re: Newton not entirely right Odd Bodkin <bodkinodd@gmail.com> - 2015-09-30 07:56 -0500
                Re: Newton not entirely right Odd Bodkin <bodkinodd@gmail.com> - 2015-09-30 07:32 -0500
          Re: Newton not entirely right mlwozniak@wp.pl - 2015-09-29 22:45 -0700
  Re: Newton not entirely right Odd Bodkin <bodkinodd@gmail.com> - 2015-09-28 11:09 -0500
    Re: Newton not entirely right Peter Riedt <riedt1@yahoo.co.uk> - 2015-09-28 18:32 -0700
      Re: Newton not entirely right kefischer <emoneyjoe@iglou.com> - 2015-09-28 21:57 -0400
        Re: Newton not entirely right Peter Riedt <riedt1@yahoo.co.uk> - 2015-09-28 19:39 -0700
          Re: Newton not entirely right Gary Harnagel <hitlong@yahoo.com> - 2015-09-28 20:10 -0700
      Re: Newton not entirely right Poutnik <poutnik4nntp@gmail.com> - 2015-09-29 07:07 +0200
        Re: Newton not entirely right Peter Riedt <riedt1@yahoo.co.uk> - 2015-09-28 22:51 -0700
          Re: Newton not entirely right Poutnik <poutnik4nntp@gmail.com> - 2015-09-29 08:20 +0200
      Re: Newton not entirely right Sylvia Else <sylvia@not.at.this.address> - 2015-09-29 16:32 +1000
      Re: Newton not entirely right Helmut Wabnig <hwabnig@.- --- -.dotat> - 2015-09-29 09:51 +0200
      Re: Newton not entirely right Odd Bodkin <bodkinodd@gmail.com> - 2015-09-29 07:38 -0500

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