[meteorite-list] Specific Gravity method /calculation error

From: j.divelbiss_at_att.net <j.divelbiss_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:20 2004
Message-ID: <020320041239.5661.3d1f_at_att.net>

Roman and others,

I guess I really am slow/dumb. your SG answers maybe too small right now...

Well if you haven't blown anything up...I'm lucky. My calculation has an
error in it from the other day. In the volume part of the equation I left out
the division by 4 when using the diameter for area. If you use the radius(1/2
diameter)...then you don't need the 4. The corrected method is below:
*******************************************************************

Then I use a cylinder(round) shaped coffee can for small items, or a straight
sided bucket for larger items to determine the volume of the object by the
change in height of the water: first without the object and then with the
object. As a slow American I use a stick rule in inches to figure this out.

so it goes like this:

determine weight in OUNCES

Determine the change in volume in the water level by measuring the:
HEIGHT without object first
HEIGHT with the object second

The difference in height in inches is then used to calculate the SG along
with some conversions factors to get it into grams/centimeter cubed.

change or delta Volume = Area of container circle x inches in height(change)
delta V =(pie or 3.14...)x diameter(inches) squared)x(height change in
inches)/4 (Note: this is where I has left out the 4)

delta V is a number in inches cubed

the conversion formula without all the details is as follows:

SG = (object in OUNCES/delta V in inches cubed)x(0.06102/0.03527) = SG in
grams/cm cubed (Note: without the 4 your SG answer would have been 4
times smaller)

0.06102 is the conversion of cubic inches to cubic centimeters
0.03527 is the conversion of ounces to grams.

For the smart users of metric the metric system....the answer is determined
by the change in volume in cubic centimeters cubed and the weight in grams or:

Weight in grams/change in Volume in centimetes cubed (now that seems easier
doesn't it) = grams/cm cubed

Bottom line is most rocks have SG of 1.5 to 3, heavier rocks full of iron

like stony meteorites are in the 3 to 5 range, and steel and it's metal
friends like iron meteorites are in the neighborhood of 7 to 8. Silver and
Lead in the 10 to 11 range and gold all the way up near 18 to 19.

Sheesh,

John
Received on Tue 03 Feb 2004 07:39:52 AM PST