Didier, my first posting to that topic contained the semtences:
> Centrifugal forces are so called fictitious forces > which are only observed from within accelerated systems. > Normal physics is done in inertial systems. Is that not pretty much what you have found out after all? 73s and my best regards Ulrich, DF6JB > -----Ursprüngliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Didier Juges > Gesendet: Mittwoch, 30. Mai 2007 02:35 > An: Discussion of precise time and frequency measurement > Betreff: Re: [time-nuts] FW: Pendulums & Atomic Clocks & Gravity > > > James, > > Where were you all week-end? > > Your explanations are so clear, it makes sense now. Thank you > very much. > > I understand now that centrifugal forces are necessary to > explain the behavior of objects when an accelerating frame of > reference is used, but not necessary (actually > counter-productive) to explain the behavior of the same > objects when an inertial frame of reference is used. > > That solves my problem and the apparent contradiction that > sometimes the centrifugal force is necessary and sometimes > not, because I did not appreciate the effects of changing the > frame of reference. > > Thanks a lot again. > > I had no idea time-nuts would drive me to brush-up on physics :-) > > Didier KO4BB > > ---- James Maynard <[EMAIL PROTECTED]> wrote: > > > The reason that the frame of reference matters is that gravity is > > indistinguishable from acceleration. (This is an assumption that > > Einstein made when deriving his general theory of > relativity. It seems > > to work.) > > > > An "inertial" frame of reference is a non-accelerating frame of > > reference. In an inertial frame of reference, Newton's laws > of motion > > work -- if you use Newton's gravitational relationship, that the > > gravitational force (weight) that each of two bodies exerts > on the other > > is proportional to both their masses, and inversely > proportional to the > > square of the distance between them. > > > > In an accelerating frame of reference (either linear > acceleration, or > > rotational acceleration, or both) additional forces, > technically called > > "fictitious" forces, must be introduced in order to explain > the motions > > of bodies with Newtonian mechanics. The "fictitious" forces > on a body > > are also proportional to the body's mass. (A body's mass is just a > > measure of its inertia: to accelerate at an acceleration > "a", a force > > "F" must be applied, and the mass "m" is just F/a.) > ...... > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
