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pfdietz • today at 3:05 AM • 1 reply • view on HN

The insulation is just more dirt.


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cyberax • today at 4:36 AM

Homework: compute the heat flux from a 40 meter radius sphere, given the surface temperature 600C and the ambient temperature 0C. Now compute the amount of insulation needed to keep its temperature above 500C for 3 months, given that dry sand has an R value of 0.25 W/mK.

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