[time-nuts] Pendulums & Atomic Clocks & Gravity

[Ulrich Bangert]

Didier,

> I am in good company :-)

No, you are not, because "centripetal" forces have the opposite
direction of "centrifugal". In fact, your NASA statement is exactly what
I am claiming too: Gravity IS the centripetal force for the satellite's
motion and clearly a centripetal force is necessary to force an circular
motion.

73 and my best regards
Ulrich, DF6JB

> -----Ursprüngliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Didier Juges
> Gesendet: Montag, 28. Mai 2007 03:30
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Pendulums & Atomic Clocks & Gravity
> 
> 
> Ulrich,
> 
>  From NASA: http://map.gsfc.nasa.gov/m_mm/ob_techorbit1.html
> 
> <quote>
> More precisely, the *Lagrange Points* mark positions where the 
> gravitational pull of the two large masses precisely equals the 
> centripetal force required to rotate with them.
> </quote>
> 
> I am in good company :-)
> (except that I used the term "centrifugal" instead of "centripetal")
> 
> Didier KO4BB
> 
> 
> 
> Ulrich Bangert wrote:
> > Didier,
> >
> >   
> >> gravitational forces, so do objects in Lagrange points. 
> These points
> >> represent areas where the centrifugal forces compensate for 
> >> gravity....
> >>     
> >
> > I am almost sure that this will again produce me a lot of 
> trouble in 
> > answering a lot of people but the idea that there are centrifugal 
> > forces which compensate for gravity are one of the BIGGEST 
> misconcepts 
> > that one may have in physics at all although it is quite common and 
> > you may find statements like that eben in (bad) physics textbooks.
> >
> > Centrifugal forces are so called fictitious forces which are only 
> > observed from within accelerated systems. Normal physics is done in 
> > inertial systems. In an inertial system consisting of earth and an 
> > satellite there are only TWO forces available: The gravity force by 
> > which earth attracts the satellite and the gravitational force by 
> > which the satellite attracts earth. They are of the same 
> magnitude but 
> > of opposite direction. That is the reason why the "sum of 
> forces" is 
> > zero for the closed system consisting of earth and 
> satellite. There is 
> > no place for any other force like centrifugal or so because 
> there is 
> > no counterforce available that would make the sum of forces zero i 
> > case a centrifugal force would exist. In case you like to 
> discuss it a 
> > bit please go on but be prepared that I will to blow your arguments 
> > into little bits. A good idea to start with is to look after what 
> > Newton's first law is saying about the behaviour of a body 
> for which 
> > all forces compensate each other. Is that what a satellite does???
> >
> > 73 Ulrich, DF6JB
> >
> >   
> >> -----Ursprüngliche Nachricht-----
> >> Von: time-nuts-bounces at febo.com
> >> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Didier Juges
> >> Gesendet: Sonntag, 27. Mai 2007 16:54
> >> An: Discussion of precise time and frequency measurement
> >> Betreff: Re: [time-nuts] Pendulums & Atomic Clocks & Gravity
> >>
> >>
> >> For the same reason that a satellite in free fall is still 
> subject to
> >> gravitational forces, so do objects in Lagrange points. 
> These points 
> >> represent areas where the centrifugal forces compensate for 
> >> gravity from 
> >> two objects instead of one for a regular satellite. The only 
> >> way to be 
> >> free from gravitation is infinite distance from mass, 
> until someone 
> >> actually invents the famous gravitational shield :-) I hope 
> >> it comes in 
> >> spray form...
> >>
> >> Didier
> >>
> >> Neville Michie wrote:
> >>     
> >>> Look up Lagrangian points on Wikipedia.
> >>> There are points of zero gravitational force, about our 
> planet. What 
> >>> is more, these points are stationary with respect to Earth, so
> >>> Doppler effects would be zero.
> >>> As the distance from Sun to Earth to Moon varies through 
> >>>       
> >> the year it
> >>     
> >>> follows that the distance from Earth of these points must
> >>>       
> >> vary on a
> >>     
> >>> small scale.
> >>> These points are good for satelites as the orbit never decays. 
> >>> cheers, Neville Michie
> >>>
> >>>   
> >>>       
> >>>> _______________________________________________
> >>>> time-nuts mailing list
> >>>> time-nuts at febo.com
> >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >>>>     
> >>>>         
> >>> _______________________________________________
> >>> time-nuts mailing list
> >>> time-nuts at febo.com
> >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >>>
> >>>   
> >>>       
> >> _______________________________________________
> >> time-nuts mailing list
> >> time-nuts at febo.com
> >> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> >>
> >>     
> >
> >
> > _______________________________________________
> > time-nuts mailing list
> > time-nuts at febo.com 
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >
> >   
> 
> _______________________________________________
> time-nuts mailing list
> time-nuts at febo.com 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
>