And now we haveChronos calling people airheads! Can’t we all just get along?
To put a different spin on the problem couldn’t we rotate the person horizontally face up at a number of different pivot points? The changing moments of inertia should give us a distribution of mass along the longitudinal axis and we could then tell what portion of mass was above the neck.
Did anyone else lie on a scale yet to see what measurement they got?
I got ten pounds and my husband got 8, this is no matter how far up we positioned our heads on the scale.
This sounds promising, except that the subject breathing in and out affects his buoyancy, and even if that wasn’t a problem, I think you’d have to allow the above described system to settle for a number of minutes before being sure you had some kind of accurate measurement. So instead of decapitating the subject in order to weigh the head, you have to suffocate or drown him.
It’s the price you pay for science, man.
What is the point of x? Obviously, it’s not needed based on the final calculcation, but what is the thinking behind introducing it in the first place?
(y-x) - (z-x) = y - x - z + x = y - z + x - x = y - z
yup, fair point 
As I’ve mentioned before on this Board, there have been a number of studies correlating the mass (and raxdius of gyration, and other such biomechamical data) of body parts with easily measurable dimensions (such as diameter of the neck). These measurements were performed on corpses, which were then cut up and measured. They found the parameters for which there were high correlations and computed formulae thatr could be used to determine the physical peopetrties of bodies so you don’t have to cut them up – you could get a reasonably good value for the weight of yopur head by measuring (as an example – I dobn’t know if these are the measurements with high correlations) neck diameter, nose-to-chin distance, and circumfeence around the temples, then plugging these into the appropriate formyulas.
Where are the formulas? You’ll have to look them up in books and journals on Biomechanics. I haven’t got the data here. The earliest ones were by Wilfrid T. Dempster at Wright-Patterson Air Force Base in the late 1950s or 1960s. They were looking at space requirements for operators (especially pilots). You can find stuff in the proceedings of the Stapp Car Crash studies, too.
I know there have been studies since. An updating of Dempster’s data took place in the 1970s, and I don’t doubt they’ve refined it since then.
In some of the above posts, there are statistics cited on weight of the brain.
Don’t forget about the skull. (and cartilige, skin, etc.)
If you weigh your head on a treadmill…
Darn you both. That was *my *joke to make!
I think Sam Stone got it, basically. The subject can breath through a thin plastic tube with negligible weight. The subject can hold his breath while the measurement is made, and I think you could pull it off in that amount of time. The subject doesn’t have to be submerged in pure water. Something denser would work better (I can’t keep my head above water without treading water).
OK, after snorting over all the absurd humor and pondering the weird science, I am left with one question, that for some reason has not been asked:
V’neef Massoud Why in hell would you possibly want to know???
It’s the first step in the process of weighing your options.
You could remove your neck from your head. I know that this is a trivial difference from the OP, but I think that science is best served by doing first, and then debating later!
hh 
Thanks bienville, for reminding me of my favorite Gavin sketch, and second overall to “Feelyaat!”. I haven’t thought of that in ten years!
Bruce: How much do you think my head weighs?
Kevin: [disbelieving] What!?!
Bruce: How much do you think my head weighs. Like if I weighed it on the scale, you know if the angle was right?
Kevin: With or without hair?
Bruce: With. [rolls eyes as if to say ‘Duh’]
Kevin: Twelve pounds.
Bruce: Now, if my head were veal, which I know it is not, if my head were veal, how much would it be worth?
Kevin: Fifty four dollars.
Bruce: [Mulls it over a moment] No, I don’t think I’ll sell.
Kevin: Really? That’s too bad.
And you thought you’d be able to make it at Post#50???
I was actually very surprised that it hadn’t been made before my Post#27!
Don Logan thanks for posting the whole exchange!
Just to reiterate, no method based on buoyancy will work. All you can measure from buoyancy is the volume of the head, not its weight. The more complicated variations of the buoyancy experiments basically boil down to “Measure the volume of the head, then measure the volume, then measure the volume, then steal underpants. From these three measurements, solve for the mass of the head”.
bienville, the entire sketch can be found here:
I thought about this for a while, and I think I understand why this is true. Whether the head is above or below the water line doesn’t matter, because the density of the whole person (plus weights you attach) determines where the water line is.
Can you debunk this idea?
Put the person on a flat plank with a movable lever line. Measure the torque on one end of the plank continuously as you move the lever line from the top of the person’s head to the bottom of their feet. From this data curve, infer how the weight is distributed from the neck up relative to the rest of the body.
Ah, I figured this one out too. The curve comes out very linear :smack: