[geocentrism] Accelerometers
- From: Paul Deema <paul_deema@xxxxxxxxxxx>
- To: Geocentrism@xxxxxxxxxxxxx
- Date: Mon, 12 May 2008 15:42:20 +0000 (GMT)
Greetings several ...
Points relating to accelerometers have appeared under several threads so I
thought that perhaps it ought to have its own. Hope
this doesn't upset anybody.
Too many points have been made in the last few days to reply to each in any
depth. Let me make a few comments.
Neville -
"Einstein taught us that gravity and acceleration are one and the same."
This is perfectly true.
Prompted by Philip's quotes from Wiki, I too read the same and other articles.
I don't see that they are one and the same. I
see that they are -- roughly -- equivalent. As Philip remarked, we are talking
here about 'artificial gravity' and if you look
more closely, it breaks down. Linear acceleration -- a rocket -- produces
increased weight but no tidal forces ie every atom is
affected identically especially those at the leading end wrt those at the
trailing end. Radial acceleration will also produce
increased weight but now we have Coriolis effects plus differential
acceleration -- your feet will weigh more than your head.
It seems to me that MS reserves General Relativity as a sort of tool of last
resort.
This strikes a chord with me. It also suggests that we don't have to bring in
Relativity if Newton can solve the problem and so
far as I can see, there is very very little in the Solar System which requires
Einstein. Certainly the gravity and acceleration
encountered can be examined adequately for our purposes here without recourse
to relativity.
Allen -
I threw you a bone on two occasions but you apparently were too busy calling me
a bonehead to notice. In any event you did not
acknowledge them, so I'll explore that point here in more detail.
You have been absolutely resolute in your refusal to address my accelerometer
proposition (the red sphere and the green sphere) so I'll propose something
similar to which you may be able to relate. If a tap is opened and water -- a
fluid -- is allowed to flow out to fall a great distance -- for convenience let
us consider that gravity and therefore acceleration is constant over the
distance of the fall -- the velocity of every drop of that water is different
from every other drop. Those at the bottom are moving
faster than those just emerging from the tap. In fact, what begins as a steady
stream, shortly becomes a string of spherical
drops as the stream of water stretches further and further until it becomes so
thin that surface tension causes it to break
into discrete portions.
Now let us take instead a long rod of metal -- a solid -- and suspend it into a
gravity field whose intensity -- over the length of the rod -- varies markedly.
If we release the rod so that it falls longitudinally, we will notice that
there will be stress over the
length of the rod due to the fact that the end closest to the centre of gravity
is accelerated at a greater rate than that
which is farthest. Theoretically at least, if the rod were to be divided at the
centre and the two halves joined with a rigid
strain gauge, the acceleration could be measured.
Taking it a little further, a very long spaceship in a very elliptical orbit
about the Sun -- longitudinally aligned with the
path -- would have its leading end subjected to greater acceleration than its
trailing end on the inbound path and the reverse on the outbound. If we were to
place an accelerometer in each end, then they would each read differently from
the other (the spaceship being rigid) and the difference could be used to
compute the acceleration. This satisfies your assertion that acceleration due
to gravity can be determined during an orbit. How you would achieve this on
Earth's surface we have yet to hear.
None of this however refutes the assertion that an accelerometer cannot detect
its own acceleration when accelerating in a
gravity field. It will only register acceleration if it is rigidly placed at a
significant distance from the centre of gravity of the object whose
acceleration we wish to determine and for all practical purposes you have yet
to show -- with numbers would be convincing -- how this might be achieved (for
example you have mentioned gravity assist maneuvers) within the distinctly
limited confines of interplanetary exploration vehicles.
For a very relevant comment, see here -
http://www2.jpl.nasa.gov/basics/grav/run.html
Finer points: At the top of this page is the question, "...what's the
difference?" Well, of course with magnetism, the
"spacecraft" BB doesn't have its own pull on the Jupiter magnet. The magnet
does all the pulling. As it does, the Jupiter
magnet feels a backward tug as it supplies the energy to accelerate the BB.
Another fine point is that if you were to place an accelerometer on the BB, it
would register acceleration as the boost takes place. This would not be true on
a spacecraft. A spacecraft feels nothing but continuous freefall as it picks up
a large increment of speed during a gravity assist. This is because of the
balance in gravitational tug as the spacecraft pulls on Jupiter and vice-versa.
[Emphasis added]
Paul D
Get the name you always wanted with the new y7mail email address.
www.yahoo7.com.au/y7mail
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