[time-nuts] Thunderbolt stability and ambient temperature

Tom Van Baak tvb at LeapSecond.com
Thu Jun 11 20:02:02 EDT 2009


> Most people thought it was coincidence of heat propagating up the bar 
> just at that time, or steam. Could be, but I still think it is real. The 
> cold end of the bar was slowly getting warmer as I carried it, but after 
> the sudden cooling of the hot end, the cold end seemed to get hot fast.

Rex,

We know each material has it's own thermal conductivity. Copper
is 401 W/m-K and steel only about 1/10th that, etc. It would appear
from conductivity tables in books that these are fixed constants.

But I wonder if near-liquid (red hot) steel has a different (e.g., even
lower) value than warm or cold steel? Is metal thermal conductivity
actually a fixed constant or is it a function of temperature over a
wide range of temperature?

If so, not only is the temperature changing when you drop the
steel in water, but also the thermal conductivity of the steel. Thus,
depending on how fast or slowly you cool it vs. how non-linear
the conductivity is as a function of temperature, I imagine you
could observe the very effect you describe.

/tvb





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