[meteorite-list] Last on Adamana for a while (I hope)

From: MexicoDoug <MexicoDoug_at_meteoritecentral.com>
Date: Fri, 2 Mar 2007 13:26:11 -0600
Message-ID: <016001c75d02$090e5340$f0068cc9_at_0019110394>

Hi again, like Sterling I will repost my message sent a while ago as it
didn't go through instantaneously and Holbrook is hot. Undoubtable the
messages will show up sometime in a couple of days so pardon the
duplication...
Best health, Doug

From: "MexicoDoug"
To: "DNAndrews"; "Meteorite-list"
Sent: Friday, March 02, 2007 12:29 PM CST
Subject: Re: [meteorite-list] Last on Adamana for a while (I hope)

Hi Dave and Jason,

I appreciate the discussion from you both, all the food for thought...

Each time I saw your posts, I didn't find any of you referencing the obvious
fact of the possible effect on travel distance of the superb orientation of
the Adamana specimen with respect to the physics. Sorry if I missed it! I
wish I had time to cook up a quantitative story, but the Adamana orientation
would contribute to a 75% faster (guess*) velocity over a longer path length
as the tumbling stones reached free fall I'm guessing. I am somewhat
comparing apples to oranges with free fall velocities and incident
velocities, but it illustrates the considerations. I'm not expressing any
opinion over this case, but just pointing out that there is a theoretical
ways to determine whether the distance traveled is ridiculous or whether
intuition can be ridiculous. Note that friction has a direct proportion to
velocity, and you can play with the projectile formula on a hand calculator
to get a feel for the angles necessary and differences in distance traveled:
distance = sin(2*ranging angle)(1-(4/3)*(vi/vt)*sin(ranging angle) which
will give you the a feel for the distance traveled by a launched projectile
subjected constant atmosphere, where vi is the initial velocity and vt is
the terminal velocity - this is the easiest way I think to get some good
intuition.

So if you can settle on the azimuth of Adamana generally being in line with
Holbrook, you might have another argument to cover relating to how quickly
the Adamana changed from straight line flight to parabolic and then nosed
down into free fall. I am guessing that the right conditions are
theoretically there to keep the possibility open from a strewn field
perspective given the nosecone sculpted orientation of the piece and its
generally higher momentum. This would be a very interesting thing to do
given all the data on Holbrook out there and if any larger oriented
specimens were collected in known points. One of my own Holbrooks is loaded
with chondrules on the surface and looks old and worn and another tiny one
is complete and asphalt black, but that's all I can say other than having
the fun with mechanics and the effect of friction on projectile angles...

I don't see the benefit searching the 'Adamana' locality on the supposition
it is another Holbrook piece unless you expect to find another equally
oriented and sized stone there (though the line that connects Adamana to
Aztec is another story)...but if you believe they are not the same fall, and
have reliable coordinates, happy hunting!

Best wishes and Health,
Doug

*from my post on this day in history of 2004:
http://www.mail-archive.com/meteorite-list at meteoritecentral.com/msg20269.html
"Also for fun, an oriented bowling ball that fractures in exactly two
hemispherical pieces traveling terminally at 150 mph will leave the two
fragments at a terminal rate of ... 106 mph a piece. That's probably why
"explosions" seem to brighten fireballs. Suddenly the greater surface area
for the same total mass steps up the overall frictional energy released and
the meteors slow down from an instantly greater potential."
Received on Fri 02 Mar 2007 02:26:11 PM PST