Re: [Phys-L] apparent weight

[Bernard Cleyet <bernard@cleyet.org>]

On 2014, Dec 11, , at 10:46, Daniel MacIsaac <danmacisaac@gmail.com> wrote:

> breathing out water vapor sleeping through the night on a cold winters night (dry air)
> is readily detected with a digital bathroom scale (try it, and drink more water).
>
> Dan M


I recently read an article giving the sources of water loss.  Surprisingly (for bc) about half is from breathing. [IIRC] I don’t know the Krebs cycle of other appropriate metabolic “pathways”, but I suspect a water source is from the metabolism of fud.  

bc  thinks we don't live on coal.

My guess from this is “more like” a third:


[How much water is lost during breathing?].
[Article in Polish]
Zieliński J1, Przybylski J.
Author information 

Abstract
Arising from the Antoine equation and the ideal gas law, the volume of exhaled water has been calculated. Air temperature, humidity and minute ventilation has been taken into account. During physical exercise amount of exhaled H(2)O is linear, but not proportional to heart rate. And so at the heart rate of 140 bpm amount of exhaled water is approximately four times higher than during the rest and equals about 60-70 ml/h. The effect of external temperature and humidity on water lost via lungs was assessed as well. When temperature of inspired air and its humidity is 35°C an 75% respectively loss of water is 7 ml/h. Whereas when above parameters are changed to minus 10°C and 25% lung excretion of H(2)O increases up to 20 ml/h. The obtained results may become the basis for the assessment of osmolarity changes on the surface of the lower airways. The increase of which is recently considered as one of the factors responsible for exercise induced bronchospasm.