[time-nuts] Pendulums & Atomic Clocks & Gravity

[Arnold Tibus]

Hello Ulrich, 
is it not important to bring into the game the satellite's velocity in 
relation to earth (on a tangential straight path deviated by 
gravitational acceleration)? 

73,
Arnold, DK2WT



On Sun, 27 May 2007 19:59:22 +0200, 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
>> >
>> >   
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