weighting

[sheck33]

Rick Murchison once bubbled...

Ok, let's try again...
How do you compute the volume of an irregularly shaped object - like, for example, a human body or an exposure suit - or a log, for that matter?
I'll use a scale, and a pool, and some weights - you use any method you choose.
Rick

I'll use a scale and a book with the density's of different materials, if the object is a mix of different materials that it is very possible to make a close guesstimate of it's average density.


what i am saying is that doing this weighing i really dont have to know how much i weigh. My body by itself is almost neutral so the only things that count are exposure protection, undergarment, tank & possibly BC depending on what you use.
I think people make it too complicated.

 

[sheck33]

-=>Larry<=- once bubbled...


Sheck - Check your CRC again! In the wonderful English system of units - the Pound has a definition as BOTH a mass and a Force! The force is, of course, in common usage assuming standard 32ft/sec2 gravity - but it is easy on us lazy folk that forget to type out "Poundals" - the correct unit.

That said - Weight and displacement define it all as does avg. density and the volume - - keep all the units straight and it works in any system.

By the Way - RobZ - Congradulations on nailing it! - I'm 6' & 225 POUNDS - and I take 8 lbs in salt water with a skin & Al80 !!

could you explain the Pound in your beautiful system
The poundforce depends on local value of the acceleration of free fall, the pound mass is a constant

in my universe forces are expressed in Newtons and mass in kilograms, the mass of an object is constant (well semi-constant really unless we refer to an objects restmass when we say 'mass')

these different systems of units are annoying

 

[Rick Murchison]

OK Sheck... let's use some actual numbers.. We have on the one hand a petite young lass, on the other a linebacker for the Colts. In their full scuba gear in the pool, both happen to need 10 pounds of weight for neutral buoyancy. The lass weighs 160 pounds in her full outfit, the linebacker weighs 320.
We're headed for the Gulf. They'd both like to be neutral there, too.
How much weight will the lass need?
How much for the linebacker?
Rick

 

[-=>Larry<=-]

sheck33 once bubbled...


could you explain the Pound in your beautiful system
The poundforce depends on local value of the acceleration of free fall, the pound mass is a constant

in my universe forces are expressed in Newtons and mass in kilograms, the mass of an object is constant (well semi-constant really unless we refer to an objects restmass when we say 'mass')

these different systems of units are annoying

Following is a direct quote of the conversion factors of pound, poundforce, poundal and their pressure equivilents - - It only remains to be said that in colloqial use - we jsut say pound!

pound (avoirdupois) (lb)23 . . . . . . . . . . . . . . . . . . . . . . . . . . . kilogram (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.535 924 E_01
pound (troy or apothecary) (lb) . . . . . . . . . . . . . . . . . . . . . kilogram (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.732 417 E_01
poundal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . newton (N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.382 550 E_01
poundal per square foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pascal (Pa) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.488 164 E+00
poundal second per square foot . . . . . . . . . . . . . . . . . . . . . pascal second (Pa _ s) . . . . . . . . . . . . . . . . . . . . . . . . . . 1.488 164 E+00
pound-force (lbf)24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . newton (N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.448 222 E+00
pound-force per square inch (psi) (lbf/in2) . . . . . . . . . . pascal (Pa) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.894 757 E+03
pound-force per square inch (psi) (lbf/in2) . . . . . . . . . . kilopascal (kPa). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.894 757 E+00

23 The exact conversion factor is 4.535 923 7 E_01. All units that contain the pound refer to the avoirdupois pound.
24 If the local value of the acceleration of free fall is taken as gn=9.806 65 m/ s2 (the standard value), the exact conversion factor
is 4.448 221 615 260 5 E+00.

sheck33 once bubbled...

these different systems of units are annoying

Agreed! I much prefer metric for anything other than esoteric discussions!
BTW - I haev no intention of getting into a position where I need to measure my restmass or even worry about a markedly different value of g!

 

[sheck33]

Rick Murchison once bubbled...
OK Sheck... let's use some actual numbers.. We have on the one hand a petite young lass, on the other a linebacker for the Colts. In their full scuba gear in the pool, both happen to need 10 pounds of weight for neutral buoyancy. The lass weighs 160 pounds in her full outfit, the linebacker weighs 320.
We're headed for the Gulf. They'd both like to be neutral there, too.
How much weight will the lass need?
How much for the linebacker?
Rick

Since they both need 10 pounds to be neutral in the pool they must both be displacing the same amount of water, therefore according to the number you gave in an earlier mail they'd need
1.025 x 10 = 10.25 lbs, they'd EACH need the same amount.
So again this points out the fact that obviously their weight is not important but the displaced volume is. And yes of course there will be some correlation between someone's volume and weight

 

[sheck33]

-=&gt;Larry&lt;=- once bubbled...


Following is a direct quote of the conversion factors of pound, poundforce, poundal and their pressure equivilents - - It only remains to be said that in colloqial use - we jsut say pound!

pound (avoirdupois) (lb)23 . . . . . . . . . . . . . . . . . . . . . . . . . . . kilogram (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.535 924 E_01
pound (troy or apothecary) (lb) . . . . . . . . . . . . . . . . . . . . . kilogram (kg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.732 417 E_01
poundal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . newton (N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.382 550 E_01
poundal per square foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pascal (Pa) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.488 164 E+00
poundal second per square foot . . . . . . . . . . . . . . . . . . . . . pascal second (Pa _ s) . . . . . . . . . . . . . . . . . . . . . . . . . . 1.488 164 E+00
pound-force (lbf)24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . newton (N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.448 222 E+00
pound-force per square inch (psi) (lbf/in2) . . . . . . . . . . pascal (Pa) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.894 757 E+03
pound-force per square inch (psi) (lbf/in2) . . . . . . . . . . kilopascal (kPa). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.894 757 E+00

23 The exact conversion factor is 4.535 923 7 E_01. All units that contain the pound refer to the avoirdupois pound.
24 If the local value of the acceleration of free fall is taken as gn=9.806 65 m/ s2 (the standard value), the exact conversion factor
is 4.448 221 615 260 5 E+00.






Agreed! I much prefer metric for anything other than esoteric discussions!
BTW - I haev no intention of getting into a position where I need to measure my restmass or even worry about a markedly different value of g!

the pound and poundforce are just 2 different units like the meter and pascal are 2 different units.

by the way you are usually measuring your restmass anyway when you step on a scale

 

[Aquamaniac]

Can I just jump in and offer a tool, (not really on topic, but i saw a good opertunity)

http://www.electricalfibers.com/tools.html

Bottom of the page is where you will find weight.

What a GREAT site.....