Joe Auricchio

You know the “30 days hath September” rhyme to remember which months have which lengths? The only one I can ever remember is September.

Or, a brief exercise in physics for those who still remember it (I don’t)

Yesterday at work I had to solve the following problem.

There is an FPGA chip that dissipates 5.7 Watts under full computation load. The chip is in an enclosure whose walls have effectively zero capacity to absorb heat. At one end of the enclosure, there is an aperture 11 mm tall and 11 cm wide, through which air flows at a rate of 40 LFM (linear feet per minute); the temperature of this air is 60 C. All the air exits at the rear of the enclosure through a similarly-shaped aperture. Assume the air becomes thoroughly mixed and thus homogeneous in temperature. Find the temperature of the exiting air.

Mooneer’s starting a hosting service. He’s considering charging $125/mbps, and wants to know how much per GB that is, assuming full-tilt usage for a month. We did the math in our heads and calc.exe. Paul said Damn. Google Calculator can’t do that conversion. I started messing with different ways of specifying units… and lo and behold it can!

125 (dollars per month per (megabit per second)) in dollars per gigabyte

This is nontrivial engineering. But I guess that’s to be expected from Google these days…