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: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] 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: [EMAIL PROTECTED] > >> [mailto:[EMAIL PROTECTED] 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@febo.com > >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>>> > >>>> > >>> _______________________________________________ > >>> time-nuts mailing list > >>> time-nuts@febo.com > >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>> > >>> > >>> > >> _______________________________________________ > >> time-nuts mailing list > >> time-nuts@febo.com > >> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > >> > >> > > > > > > _______________________________________________ > > time-nuts mailing list > > time-nuts@febo.com > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
