Pitanje iz fizike

[ sborovic @ 09.06.2012. 19:55 ] @

Pisao sam na nekom stranom forumu, zato je na engleskom, pretpostavljam da nije problem.

Back in class we had the following problem:

The air we breathe is about 21% oxygen, by volume. Exhaled air contains about 14% of oxygen. The absorption of oxygen within the lungs takes place in tiny spherical compartments called alveoli which have a diameter of the order of 0.1 mm. Estimate the number of oxygen molecules absorbed in one breath in each of the alveoli. (Assume that body temperature is 37°C.)

I assumed that the pressure inside the alveoli is 1 atm, that

and calculated the volume using

Now,

and End-of-chapter solution is

What am I doing wrong?

Dakle, u čemu je problem?

[ Odin D. @ 10.06.2012. 05:12 ] @

Možda je dati rezultat pogrešan.
6.9E12 predstavlja više od pola od ukupnog broja molekula, a to nije moguće, kad je maximum 21%.

Razlika između tvog rezultata i tog navedenog je skoro 8 puta, što znači da ni pod nekim drugim "približno razumnim" pretpostavkama (rezltat omaškom izračunat sa sobnom temperaturom gasa, 2-3 puta veći pritisak u plućima...) ne bi moglo da se nagura na 6.9E12.