Re: Mass/Energy Conservation

[Doug Craigen <dcc@ESCAPE.CA>]

David Abineri wrote:
> I presume that, if you eat a pound of food, you will gain a pound of
> weight at that time.
>
> Now, over many days, one eats many pounds and produces many pounds of
> waste. How can one describe the mass and energy balance here. If the
> waste is less mass than the food, do you necessarily put on weight?  If
> not what happens?
>
> Thanks for any guidance,       Dave Abineri

I assume that you are remembering to include drinking water in the
"food" calculation.  There are other mass exchanges as well with
sweating and respiration.  We breath out a lot of water vapor (its been
-30 here in Winnipeg this week, I've seen that one a lot) plus exchange
O2 for CO2.  Hence there is a net loss of weight from breathing.  This
might be an interesting back of the envelope calculation.

\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\

Doug Craigen
          http://www.dctech.com/physics/about_dc.html