Article: <5f1grb$3fo@dfw-ixnews11.ix.netcom.com>
From: saquo@ix.netcom.com(Nancy )
Subject: Re: Hale-Bopp THEN and NOW
Date: 26 Feb 1997 14:20:27 GMT
In article: <ESjMkmABB2EzEwUX@spacetime.demon.co.uk>
Chris Lawrence writes:
> ZetaTalk[TM] writes:
>> If the comet has slowed and has the Sun more to it's
back
>> than to its side, WHY would the comet NOT start falling
>> back toward the Sun, directly.
>
> BECAUSE it already has a component of velocity tangential
> to the direct path from it to the sun. ... The way in which
an
> oribiting body moves is a vector sum of it's current
velocity
> and that velocity which any forces on it (i.e. sun) creates.
> Chris Lawrence <chris@spacetime.demon.co.uk>
(Begin ZetaTalk[TM])
Examine that tangential path. It has various components. A curve
is a COMBINATION of a forward motion and a sideways tug, always.
There is no such thing as a curved motion, except as a
combination of forces, which you may call vectors if you insist.
Is this not the case, that in vector analysis, you must draw TWO
vectors to equate to a curve? Given that, draw the comet on the
long stretch away from the Sun as vectors.
Now, given that there is NO vector moving the comet to the left, how does it get way over there for its re-entry into the Solar System?
(End ZetaTalk[TM])
In article: <ESjMkmABB2EzEwUX@spacetime.demon.co.uk>
Chris Lawrence writes:
> ZetaTalk[TM] wrote:
>> WHY would it move increasingly toward the side instead?
>> Motion is in a straight line unless perturbations occur
...
>> WHY would it drift to the side over this dramatic swath
>> of space
>
> If you whirl a rock round on a string, there is an
acceleration
> towards the end of the string you're holding (if there
wasn't
> the rock would not move in a circle) and this continuously
> changes the velocity of the rock. That doesn't mean that
> this acceleration causes the rock to smash into your hand,
> does it?
> Chris Lawrence <chris@spacetime.demon.co.uk>
(Begin ZetaTalk[TM])
Where the twirling rock on the end of a string is often used as
an analogy for planets in orbit around the Sun, there are several
significant differences. The planets are not bound to the Sun in
the same manner as the rock is bound to the arm, by the length of
string. The string keeps the rock from moving AWAY, where a
planet is free to do so. Likewise, the rock is not moving about
in a circle on its own, it is being THROWN, continuously by a
tugging arm. Freeze the arm that the string is attached to, and
see how long the rock stays in motion!
The comet exiting from the Solar System is likewise not bound
to the Sun except as the sum of the forces affecting it may
equate to that. Thus, one must examine these forces, and analyze
their effect, to understand why the cosmos works as it does. What
happens when the swinging arm that sets a rock on the end of a
string, LETS LOOSE of that string? Does the rock continue in a
curve? Does the rock circle round and return after a few years?
It moves in a straight line, away from the arm that THREW it,
until gravity brings it to the Earth and the friction of the
atmosphere slows it. Plonk. No perfect ellipse.
(End ZetaTalk[TM])