Leo Bueno > wrote:

>
> Because it is not easy to measure the temperature INSIDE the bottle.
>
> Given that "room temperature" is generally uniform in the
> climate-controlled world and so are refrigerator temperatures, a
> refrigeration time rule of thumb may not be bad approximation.

ok, in that case, take a time constant of 20 mn (saying tau), as a rule
of thumb, then, having T1 the romm temperature where the bottle was,
take T2 the fridge temperature, the bottle temperature will follow :

Tbottle = T1 + (T2 - T1).e^( - time / tau)

time being expressed in the same unit as tau...

for time in hours (tau = 1/3) gives :

Tbottle = T1 + (T2 - T1).e^( - 3.time)

giving, for time :

time (in hours) = (ln((T2 - T1)/(Tbottle - T1)))/3

as far as i remember well algebraic computation ;-)

--
Yvon Thoraval