I had "Unusual sources of energy" class at University. One day we were sitting in the classroom, the teacher was there but the class didn't started yet. I was eating one of those extruded styrofoam cracker and I noticed on the packaging there was a nutrient information, I converted it 1:1 to electric energy and calculated that one cracker could power single LED diode for 6 months. It seemed wrong so I told it to the teacher and asked him how they actually calculate the energy of various foods and when he said they burn it, I bursted into laughter because I honestly imagined some more sophisticated method.
Re:How pencil tire pressure gauges work
by sidpatil on Saturday December 10, 2022 @09:39AM
(#33932986)
I believe they no longer use the burning method [1] for measuring food energy, since it overestimates energy of high-fiber foods (fiber doesn't get burned when in the body, but it does get burned during measurement.) I believe nowadays they estimate the caloric content based on the fat, carbohydrate, and protein content of the food.
A good youtube video on the subject of the energy content of food and how efficient the body is at using it.
Turns out, it works precisely how I would have expected it would work, and indeed, probably using the first approach I would have used for designing such a thing (granted, I'm not a mechanical engineer.)
Most things I learn about do NOT fit expectations that well. Truly a simple, practical device.
Also, incidentally, all the pencil gauges I have are +/- 5 psi relative to my digital gauge, so despite all these balances it might only be an approximate technique after all.