On 30 May, 00:38, "Max Keon" wrote:
"Max Keon" wrote in message
u...
"George Dishman" wrote in message
...

Forgive me for starting a new thread, but the old one has become
fairly redundant due to the huge bulk of posts that seem to serve
no purpose other than to bury the thread under a layer of wader
depth bull****.

I totally agree.

much snipped as there is a major probleme here
That means that any time, the acceleration adds an
amount to the velocity which is equal to the product
of the time and the acceleration. It doesn't add or
subtract from the radius, I don't know where you got
that idea.

For example, if an acceleration of 2m/s^2 acts for
50s then the velocity will change by 100m/s.

I'm inclined to think you actually believe that George, which is
a bit disconcerting.

I hadn't realised you had a problem with that. Of
course it is fundamental, the word acceleration
is defined as the rate of change of velocity and
is unarguable and the other equations you have
tried to use are all derived form this under
various conditions.

I'll snip the rest and concentrate on this major error, which is
obviously the root of all of the confusion.

What you say is true for Mercury while in its stable eccentric
orbit around the Sun, so long as the anisotropy isn't included.

What I said above is true for all objects changing
speed for any reason whatsoever under any circumstances.

Certainly _not_ under any circumstances George.

Yes, under _any_ circumstances Max. The word
"acceleration" is _defined_ as rate of change
of velocity so in a short time dt the velocity
will change from an initial value v_i to a final
value v_f given by

v_f = v_i + a * dt

where a is the acceleration. v_i, v_f and a are
all vectors and can be handled as x and y
components as I do in the code. (You need z too
in general of course but our orbits are two
dimensional).

Your calculations
apply for any normal trajectory taken by an object naturally
moving to or from a gravity source.

No, it applies to _all_ motion of _any_ nature
whatsoever. That is fundamental to the whole
of dynamics and the process of integrating
acceleration to find velocity is pure maths.

....
You of course agree that an object in a sustainable concentric
orbit around the Sun will not shorten the radius between it and
the Sun?

Obviously since concentric just means at constant
radius.

You also agree that the radius will shorten at the full
gravity rate only if its orbital speed is zero. AND ONLY THEN?

No! You are missing the whole point. Compare two
similar but slightly different motions for Mercury.
In the first it is in a perfectly circular orbit at
some radius with an orbital speed of 48km/s:


^
|
Sun M
|

In the second we have a snapshot of part of some
more complex path when the planet is also moving
at 48km/s:

^
\
Sun M
\

The difference is in the direction of motion, not
the speed. If the angle between the two paths is
just 1 degree the Mercury will move 48000*sin(1)
or 837.7m closer to the Sun in 1 second and that
is without even considering additional acceleration
effects.

The same of course applies for an eccentric orbit.

Do you reject any of that so far?

It is virtually all wrong, you don't seem to know the
definition of acceleration and you have completely
failed to grasp the importance of the direction of
motion.

There's no point in replying to the rest of your post until
this has all been cleared up. You are repeating the same old
mistakes over and over again, again.

I'm not making any mistakes Max, everything I
said follows directly from the definition of
velocity and acceleration. The problem is that
you have forgotten about the effect of the
direction of motion and discarded fundamentals
to try to get the answer you want. Velocity is
the integral of acceleration, _always_.

The gravity force is pointing directly at the Sun, ...

Yes, and Mercury is moving almost at right angles to
that, so the major influence is to change the direction
of motion, not the speed.

so unless
Mercury falls closer to the Sun on average its orbital speed
cannot be increased. Adding a new force does not change the pull
direction, so orbital speed cannot change from the normal unless
the average radial length changes. Can you now see that?

Change of orbital speed is a secondary effect due to
the slow reduction of radius (Mercury moves faster
than the outer planets), what you are missing is that
increasing or decreasing the pull towards the Sun
changes the rate at which the direction of motion
alters. My code includes that effect and the results
follow.

George