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Measuring the Volume of My Body

Date: 09/17/2003 at 11:42:54
From: Adelfa 
Subject: Density of human

What is the most efficient way of calculating the density of a human 
being?  If actual experiment is not possible, what would be different 
conversions I have to do to get my volume?

I have considered doing the displacement where I will use the bath 
tub as the container. Then submerged myself in it.  The problem is I 
cannot do this alone.  Who will measure the level of water after I 
go into the tub?  So, I am looking for another means of calculating 
my density.

Date: 09/17/2003 at 14:45:52
From: Doctor Rick
Subject: Re: Density of human

Hi, Adelfa.

If you float but just barely, as most of us do, then we know already 
that your density is slightly less than that of water, 1 gram/cm^3. 
How precise do you want to be? I don't think that we could calculate 
your volume from measurements precisely enough even to predict 
accurately whether you would float or sink. We are left with 
something akin to the displacement method that you are rejecting.

I'm thinking about a related method that does not require measurement 
of the displaced volume of water. Assuming you do float, you could 
completely submerge yourself in a swimming pool, taking a bunch of 
weights with you, enough to hold you down. Drop the weights one at a 
time until you have neutral buoyancy (just barely starting to drift 
upward). The combined mass of your body and the weights you are still 
holding is equal to the mass of displaced water, that is, the density 
of water times the total volume of your body and the weights. From 
this, knowing the mass and density of the weights, along with your 
own mass, you can determine your volume.

- Doctor Rick, The Math Forum 
Associated Topics:
High School Physics/Chemistry

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