[meteorite-list] Meteorite Hammer Time - You Pick the Target!

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Sun, 13 Nov 2011 23:11:06 -0500 (EST)
Message-ID: <8CE709A90DC6BBF-6A8-55605_at_webmail-m101.sysops.aol.com>

Hi Mike,

To save you the trouble of going up the roof let me make another
suggestion which you can write a simple paper which can be published in
a scientific journal for your birthday that no scuientists have thought
of yet. That way those of us who have PETA (PETM) style sit-in
tendencies will turn your party into a boring assignment that will give
you something to remember your whole life with pride ;-)

Problem: We know a lot about free fall of meteorites about 30% of the
meteorites on earth but little to my knowledge has been done on the
other 70%. The 30% reach a terminal 'free fall' velocity and then
abruptly stop upon impact. But the other 70% land in water and
continue falling. So we're curious. Will a meteorite of your's size
reach a free fall velocity smoothly or will there be turbulent flow at
first, and what is the relationship of free fall velocity under water?
Can we verify it follows:

vf = sqrt(g*d*r/r0)


vf = (free fall velocity under water, cm/s)
g = 980 cm/s2
d= mean meteorite diameter (cm)
r=meteorite density (3.4 g/cc)
r=water density = (1.0 g/cc)

Experimental

- go to a pool (preferably filled with ground water).
- have measurement lines painted on the side of the pool and a camera
trained on the path of the hurled downward falling meteorite, like the
kind Mom used to do on the wall every birthday until you turned 8.
- train the camera on the path and use a stick to calibrate any
refractive effects.
- have a good frame rate so the velocity of the meteorite can be
measured close to the impact point with the water and until it comes to
rest under water
- do a few different hurl speeds, from surface drop to high hurl.

Calculations

- using the frame rate get a few velocities and see if there is any
discontinuity.
- if there is discontinuity, how fast till continuity?

Discussion

Did the meteorite tend to its water free fall velocity quickly?
Did it impact the water above or below its free fall velocity? Could
you hurl+drop speed increase it to faster than its free fall velocity?
What implications will tjhis have for the sizes of the largest
meteorites under water?
Is it possible that one ton solid stone meteorites hold together
underwater even though on land we haven't seen this?

Conclusion:
Up to you ;-)

Then post a preprint on the list...

Kindest wishes
Doug
Received on Sun 13 Nov 2011 11:11:06 PM PST