[time-nuts] Thunderbolt stability and ambient temperature

Chuck Harris cfharris at erols.com
Fri Jun 12 00:11:58 EDT 2009


Bruce Griffiths wrote:
> Perhaps the answer is somewhat more prosaic.
> 
> Radiation and convective losses from the hot end of the bar are significant.
> In particular the radiative loss is (as a first approximation)
> proportional to the difference of the 4th powers of the bar temperature
> and ambient temperature.
> When one modifies the model to include radiative losses near the hot end
> that are in effect switched off by cooling then some overshoot can occur
> at the hand held end of the bar.

Yeah, when you dunk the rod in water, the relatively small radiative and
convective losses of heat are replaced by a terrifically large conductive
loss of heat.

The extremely quick cooling is why you dunk the bar in water in the first
place.

-Chuck Harris




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