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## Re: Ballistic Theory and the Sagnac Experiment

 Subject: Re: Ballistic Theory and the Sagnac Experiment "" 29 Mar 2006 19:20:40 -0800 sci.astro, sci.physics.relativity, sci.physics
 ```Jeff Root wrote: > Jim Greenfield replied to Jeff Root: > > >> George Dishman wrote: > >> > >> > (3) AND (4) ARE QUESTIONS, NOT REASONS. > >> > >> Actually they're scenarios, which were described in order > >> to pose and answer the questions. > > > > Agree. George is running interference > > I can't even guess what you mean by that remark. > > >> Of course, a scenario doesn't cause Doppler shift, any > >> more than a question does. > >> > >> The question is: > >> What causes the Doppler shift in scenario (3)? > > > > Make that question (a) > > Answer: Change in position at instant of firing > > That's good. Since the position at the instant of > firing is the only thing that changes, that must be > what causes the Doppler shift in this scenario. > > > Question (b) > > What causes the Doppler shift in scenario (4)? > > Good question. I should have included it in my post. > > > Answer: Increased bullet velocity > > Okay, that's interesting. You say that the cause of the > Doppler shift in scenario (4) is different from the cause > in scenario (3). > > > .........(for an extra 1/2 mark, the position change > > is incidental) > > Yes. Scenario (4) has both a change in position and a > change in speed at the instant of firing. > > Compare the amount of Doppler shift in the scenarios. > In my animation, the times between bullet hits on the > targets are: > > 1) 15.0 frames > 2) 15.0 frames > 3) 7.5 frames > 4) 10.0 frames > > So the frequencies are: > > 1) 0.066 per frame > 2) 0.066 per frame > 3) 0.133 per frame > 4) 0.100 per frame > > Cases (1) and (2) have no Doppler shift. Case (3) has > the most Doppler shift, and case (4) has some Doppler > shift, but less than case (3). > > Case (4) has exactly the same change in position that > case (3) has. Shouldn't that change in position cause > Doppler shift? Since the position changes by the same > amount in both cases, shouldn't it cause the same amount > of Doppler shift in both cases? > > Why is the Doppler shift in case (4) less than that in > case (3)? The only difference between the two cases is > that case (4) also has an increase in speed. Somehow, > the increased speed in case (4) caused the amount of > Doppler shift to be less than it is in case (3). > > > Question (c) > > Which of the two ACTUALLY caused the Doppler shift, and > > where is the evidence? > > Answer: (4), because it demonstrated increased kinetic > > energy delivered to the target, whereas (3) did not. > > Again, (4) is a scenario, not a cause of Doppler shift. > Scenarios do not cause Doppler shift. If you mean that > a change of speed causes Doppler shift, then say so. > > Sticking the word "ACTUALLY" into the sentence doesn't > accomplish anything. We agree that the Doppler shift in > case (3) is caused by the change in position. We haven't > quite figured out yet what is going on in case (4). > > You say that the change in speed in case (4) causes the > Doppler shift. I point out that, if change in position > causes Doppler shift in case (3), then it must also cause > the same amount of Doppler shift in case (4). > > But case (4) has less Doppler shift than case (3), even > though the only difference between the two is that there > is an increase in speed in case (4). > > If an increase in speed causes Doppler shift, shouldn't > there be more Doppler shift in case (4) than in case (3)? > > And if an increase in speed causes Doppler shift, why is > there no Doppler shift at all in case (2)? Most covered before, except to comment that your "belief" in the animation that it is a true representation of reality. I disagree! As v=frequency X wavelength, an increase in bullet v = corresponding increase in frequency, and NO CHANGE indicated for wavelength. I couldn't be bothered responding more to (3). My original analogy had the machine gun mounted on an aircraft. To discuss a "scenario" where a plane stops to fire is nothing short of pathetic. The reason for the doppler is (4), as presented. Jim G c'=c+v PS: Are you one of these individuals, who because they "saw it" on a computer animation, is convinced they are looking at reality? Hint: We are NOT about to be invaided by aliens. ```
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