> George Dishman wrote:
> > jgreenfield@xxxxxxxxxxx wrote:
> > > George Dishman wrote:
> > > > jgreenfield@xxxxxxxxxxx wrote:
> > > > > George Dishman wrote:
> > <snip>
> > > > > _IF_ (2) scenario was considered, it is obvious that the kE imparted
> > > > > to the bullet
> > > > > by way of the gun's motion (as separate from the charge) is cancelled
> > > > > by hte reversal of the gun's direction (as it returns to the firing
> > > > > position)
> > > >
> > > > Don't be stupid Jim, the speed of the bullet isn't
> > > > changed by what the gun does after it fires.
> > >
> > > Idiot! Which way are the other bullets in the magazine travelling
> > > half a rev after the first is fired????????????
> > > What speed would that be?
> > > Does "negative" ring a bell?
> > Do you seriously believe the motion of the magazine
> > affects the speed of the bullet relative to the target
> > when that bullet has already been fired?
> George, we are discussing a whole MAGAZINE of bullets!
No we are not, you said "it is obvious that the kE imparted
to THE bullet by way of the gun's motion (as separate from
the charge) is cancelled by the reversal of the gun's direction
(as it returns to the firing position)."It is that comment about
an individual bullet that I responded to.
> What is happenning to the others ( after first is fired (in (2))
The kinetic energy imparted to the first bullet is
unchanged by the movement of the magazine after it
is fired. Similarly the kinetic energy of the second
bullet depends only on the speed of the gun at the
moment when it is fired and so on. Each bullet has
an energy which is determined by the charge and the
speed of the gun at the moment of firing and the
history of the gun's motion between shots does not
affect that energy.
> > > I asked that (3) be considered (?) in order for it to be REJECTED!
> > I know, but it worked the other way and meant
> > that it was YOUR explanation that needed to
> > be rejected, that's why you wouldn't look at the
> > question even after you asked it.
> Bullshit. Schoolyard experiment (stone throwing) proves otherwise.
Try it. Throw a stone when standing still, then move
forward and stop. Throw another stone. Is the damage
any greater than staying stationary and throwing them?
Neglecting effects like air resistance the answer is
However, there is a Doppler shift, the time between
stones hitting the wall is less than the time between
> > > Hint: It is customary for intelligent people to REJECT a scenario as
> > > being
> > > correct, when evidence UNAMBIGUOUSLY is against it, and in favour of
> > > one where the evidence is in support.
> > Hint: It is customary for intelligent people to think
> > about scenarios. It is customary for intelligent
> > people reject or accept explanations, not scenarios.
> > The evidence from the scenarios is that a change of
> > energy is not the cause of the change of arrival rate
> > and should be rejected as an explanation.
> You are becoming a very devious and mischeivous poster!
No, I try to make it clear that you say the cause is the
bullet speed and I have quoted you in the past, but the
kinetic energy and speed are directly related given
On the other hand, you have netly deflected the
conversation, the point is that intelligent people
don't reject questions just because they can't
answer. Scenario (3) is NOT supposed to be an
explanation, it is a picture that you should
consider because it tests the validity of your
suggested explanation of Doppler.
> I have NEVER said that an energy change is the CAUSE of a particular
> observation: what I HAVE said, is that the energy change is irrefuteble
> evidence of the reason FOR it.
And what I have said is that it is refuted by
scenario (3) since a Doppler shift occurs without
a speed (or energy) change.
> > > > I'm not going to waste any more time on this Jim,
> > > > you obviously have some serious reading impairment.
> > > > I just said the folowing:
> > > >
> > > > "The rifleman's motion at the time of firing does
> > > > also produce the change of impact energy ..."
> > >
> > > ...and (3) doesn't!!!!!!!!!!!!!!!!!!!!!
> > > THEREFORE IT IS (4)
> > > What part of "evidence" don't you understand?
> > The logic I understand and you don't is that in (3) a
> > Doppler shift occurs but an energy change doesn't
> > therefore energy change is ruled out as the cause
> > of Doppler shift. You actually gave the correct answer:
> But this is CRAP! An energy change DOES OCCUR.
"in (3) a Doppler shift occurs but an energy
No energy change occurs in (3), you just said
so a few lines above with lots of exclamation
> Look at the target! How come , in (4) it sustained more damage than
> (1), but in (3) it DID NOT??????????????????
Yes Jim, in (3) it did not, so why did you say
"An energy change DOES OCCUR".
> > jgreenfield@xxxxxxxxxxx wrote:
> > > Jeff Root wrote:
> > > >
> > > > The question is:
> > > > What causes the Doppler shift in scenario (3)?
> > >
> > > Make that question (a)
> > > Answer: Change in position at instant of firing
> > I did say that if you answered my question I would
> > address yours so I suppose I need to do that next:
> > > You are still welcome to discuss HOW energy differs, and why.
> > > I doubt that you will though--------long since in your "too hard"
> > > basket.
> > As far as the riflemen are concerned, in the
> > Newtonian approximation, kinetic energy, the
> > energy that determines the damage to the target,
> > is given by 1/2 m v^2 where v is the speed of the
> > bullet relative to the target at the moment of
> > impact.
> > Going back a few weeks though to your photon
> > analogy which is what I said I would discuss, it's
> > even easier, the energy of a photon is proportional
> > to the frequency. By analogy a burst of bullets
> > hitting a target at 20 round per minute does twice
> > as much damage as a burst of 10 rounds per
> > minute and the same duration. Hardly surprising
> > is it?
> There were only 10 rounds in the magazine!
Says who? I warned you some time ago you would
find there were problems with using bullets as
> Wherefore the 20?
For photons, we know the energy depends on the
frequency even if we are comparing two static
sources, say one blue and one red. The speed
of the light from the two sources must be the
same if the are both stationary but one fires
at twice the rate of the other and does twice
the damage. That can only be modelled in your
analogy if photons are bursts of the same
It also makes some sense from a QM consideration.
Photons are quantum beasties and the uncertainty
principle says the duration depends on the accuracy
of our knowledge of the location of the target.
> It is these 10 rounds, compared to 10 from (3)
> which had the added energy in (4) compared (1)
> Hayley (year 10 highschool, worked that out in about 5 seconds)
You alternative I believe is that the change is
due to the changed speed. For bullets hitting at
twice the rate, the speed of the gun needs ot be
0.5c. The speed of the bullets would be 1.5c and
the energy increased by a factor of 1.5^2 or 2.25.
For photons though, double the frequency only
doubles the energy. Speed change is therefore
ruled out as the cause - it gives the wrong value.
At Hayley's age, I wouldn't expect her to be
sufficiently familiar with Doppler and kinetic
theory to spot that.
> You're Rooted
I know the subject.