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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.05 04:02:00 -
[1]
All the laser recoil topics and graphics card power consumptions mentioned in all the threads combined with some RL talks about nutrition got me thinking, and all of a sudden I was curious enough to calculate something.
The average human needs about 2000 kilocalories' worth of food energy in order to "function". 2000 kcal = 8368000 joules 8368000 joules / 86,400 seconds (in a day) = 96.8518519 watts
A human needs about as much energy to live as it takes an old style lightbulb to function ? That's NUTS !
:sigh:
If only we could run on electricity instead of food... _
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.05 04:18:00 -
[2]
Originally by: Selinate human body is not 100% efficient
If it would be 100% efficient, it would require even less actual energy. I believe my point was that 100 W is an incredibly low average.
Quote: Also, we actually require around 2000 calories (not kilocalories) a day to maintain healthy diet....
That's a common misconception. The humans need roughly 2000 "Cal" (or "food calorie", or "dietary calorie" if you prefer). 1 Cal = 1000 calories. So, basically, kilocalorie. Either way, humans need roughly 8 MJ of energy per day. _
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.05 16:54:00 -
[3]
Yup, one cubic meter of water is quite literally one ton of water. _
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.05 17:15:00 -
[4]
Yup, one cubic meter of water is quite literally one ton (1000 kilos) of water.
Also, you're not exactly heating those unknown numbers of kilos of squishy watery meats, you're maintaining their temperature - waste heat from work done only needs to compensate for radiative heat losses , which depend on outside temperature and level of insulation between the human body and the environment. In fact, that's why we even sweat - whenever we make some effort, the extra waste heat can't be efficiently radiated, so we cover ourselves with water which evaporates, and the phase transition of water from liquid to gas "absorbs" a lot of heat in order to occur. Radiated heat depends on surface area, while caloric capacity depends on volume/mass. That's why small hot-blooded animals need to eat so much food (compared to their body weight) while larger ones eat far less (again, speaking as a percentage, not absolute number).
Those 2000 kcal are the average use per day for the average human doing average stuff while dressed appropriately in a comfortable environment. If you're looking at people that do a lot of physical work/exercise, it's obvious they need far more than that. Some athletes have diets that border on 10000 kcal per day just to maintain weight, but then again, you're looking at a full-time exercise regimen for them. Same goes for people that are put in a colder environment without adequate clothing, or a much colder environment regardless of insulating clothing. You can easily burn up 500-1000 more calories during the winter than during the summer just by not staying all day long in heated indoor environments. _
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.05 23:21:00 -
[5]
Edited by: Akita T on 05/06/2011 23:21:59
Nah, the Matrix was last-minute executive meddling. The original plot was that they're using the human brains as organic computers to massively supplement their own processing power.
But since the average movie goer was deemed too stupid to understand what that means, they switched it to "humans as batteries". Imagine how the scene would be different if Morpheus would hold a CPU chip in his hand instead of a battery.
_
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.06 07:08:00 -
[6]
Originally by: Surfin's PlunderBunny But I like food
On the other hand, no more need for toilet breaks... _
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.08 22:59:00 -
[7]
On the other hand, you might need periodic refills of "repair materials"... think printer cartridge, but replacing your digestive system.
_
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.12 23:27:00 -
[8]
Well, if you "run hotter" it's obvious you'll use up more energy. There's absolutely no question about that. How much more... well, that's another story. I'm thinking, probably 10% extra, 20% maybe tops. Total guesstimate though. _
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.06.12 23:48:00 -
[9]
Edited by: Akita T on 12/06/2011 23:57:22
Originally by: Xenuria Do you know of any scientific way of finding out exactly how much?
Count calories being consumed, keep measuring weight. 1 kg of body fat is on average the equivalent of very roughly 7700 Cal (~32 MJ). Or if you prefer, roughly 3500 Cal/pound. Calculations should work regardless of whether you're gaining, losing or maintaining weight, as long as you keep a precise caloric intake count AND you maintain the same fitness level (same non-fat mass). No idea of caloric value of human muscles, so it's important to not vary in muscle mass at all. It's actually best if you maintain your total weight too.
Ideally, you will measure your weight in such a way as to minimize variations of body water content and "waste" ballast - try to remain well hydrated overnight (drink sufficient water when you go to bed, try to avoid too much variation in salt content that would affect water retention) and measure your weight after you go to the bathroom in the morning right after waking up (after performing both of the usual bodily functions).
average daily calories burned = [ total calories eaten + 7700 * (Weight at start - Weight at end) ] / number of days passed (use 3500 instead of 7700 if you use pounds instead of kilograms) _
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.07.08 10:21:00 -
[10]
Edited by: Akita T on 08/07/2011 10:24:13
Originally by: Kirja Dont forget that humans are also self-learning, self-replicating, self-repairing, evolving, adapting (both mentaly (software) and physicaly (hardware)) to changes etc beings. Imagine a machine doing all of that and running on 100W + some minerals per day. A lot of great engineers and scientists said that the more they learn about their trade the more they become impressed by technical solutions that "evolved naturaly". No wonder a large part of brightest minds in human history was deeply religious.
Before people learned to work with genetic algorithms, maybe.
For instance ... http://www.talkorigins.org/faqs/genalg/genalg.html#examples:electrical
Quote: A field-programmable gate array, or FPGA for short, is a special type of circuit board with an array of logic cells, each of which can act as any type of logic gate, connected by flexible interlinks which can connect cells. Both of these functions are controlled by software, so merely by loading a special program into the board, it can be altered on the fly to perform the functions of any one of a vast variety of hardware devices.
Dr. Adrian Thompson has exploited this device, in conjunction with the principles of evolution, to produce a prototype voice-recognition circuit that can distinguish between and respond to spoken commands using only 37 logic gates - a task that would have been considered impossible for any human engineer. He generated random bit strings of 0s and 1s and used them as configurations for the FPGA, selecting the fittest individuals from each generation, reproducing and randomly mutating them, swapping sections of their code and passing them on to another round of selection. His goal was to evolve a device that could at first discriminate between tones of different frequencies (1 and 10 kilohertz), then distinguish between the spoken words "go" and "stop".
This aim was achieved within 3000 generations, but the success was even greater than had been anticipated. The evolved system uses far fewer cells than anything a human engineer could have designed, and it does not even need the most critical component of human-built systems - a clock. How does it work? Thompson has no idea, though he has traced the input signal through a complex arrangement of feedback loops within the evolved circuit. In fact, out of the 37 logic gates the final product uses, five of them are not even connected to the rest of the circuit in any way - yet if their power supply is removed, the circuit stops working. It seems that evolution has exploited some subtle electromagnetic effect of these cells to come up with its solution, yet the exact workings of the complex and intricate evolved structure remain a mystery.
Who exactly can believe in a "higher power" after THAT one ?
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.07.08 14:55:00 -
[11]
Originally by: Mudkest the point was not that there are nuclear reactions going on in the human body, jus that the 100w is needed to start reactions.
Nope, that 100W average across the entire day is the combined power output of all those chemical reactions that come from "burning" the food. Probably even less, considering you don't take out all the energy from the food. |
Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.07.08 15:20:00 -
[12]
Edited by: Akita T on 08/07/2011 15:21:57
Originally by: Selinate Human beings have wildly different metabolic rates based on what they eat and how they spend their lives. This is why this thread makes me twitch a little....
ahem
Originally by: Akita T Those 2000 kcal are the average use per day for the average human doing average stuff while dressed appropriately in a comfortable environment. If you're looking at people that do a lot of physical work/exercise, it's obvious they need far more than that. Some athletes have diets that border on 10000 kcal per day just to maintain weight, but then again, you're looking at a full-time exercise regimen for them. Same goes for people that are put in a colder environment without adequate clothing, or a much colder environment regardless of insulating clothing. You can easily burn up 500-1000 more calories during the winter than during the summer just by not staying all day long in heated indoor environments.
Of course there's a lot of variation, but you have a rough order of magnitude for "the average person" while mostly doing "office work" close to 2000 kcal/day. |
Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.07.08 16:23:00 -
[13]
Edited by: Akita T on 08/07/2011 16:27:30
Originally by: Selinate There's even a wide variation between different times of the day for a single person, though. Saying something runs on an average of some given power for the vast majority of things is... Well, to say the least, its a useless number. If you want to go over average amount of energy used on a given day (which has apparently been gone over in this thread), that's a different deal, and actually a meaningful number...
There's no practical difference between saying "consumes on average 100W" or "total average daily power usage is 2.4 kWh" or "average daily consumption is 8.64 GJ" or "average daily usage is 2000 kcal", it's the same thing.
Originally by: Selinate
Quote: Food calories are kilocalories, i.e., the amount of energy required to raise one LITER of water 1ŚC. A calorie is the amount of energy required to raise 1 milliliter of water 1ŚC. The "kilo" is dropped from food labels for simplicity.
No, a kilocalorie is 1000 calories.
Also known as "FOOD calorie" or "Cal", equal to 1000 calories or 1 kilocalorie. They're all the same thing.
"Food calories, or the "calorie" units used often in nutritional contexts, measure amounts of energy 1000 times greater than the units in scientific contexts known also as calories, or gram calories (cal). Food calories are thereby referred to less ambiguously in some formal contexts as kilocalories (kcal). One food calorie is equal to 4.184 kilojoules. Within the European Union, both the kilocalorie (kcal) and kilojoule (kJ) appear on nutrition labels. In many countries, only one of the units is displayed."
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Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.07.08 16:53:00 -
[14]
Originally by: Selinate
Originally by: Akita T There's no practical difference between saying "consumes on average 100W" or "total average daily power usage is 2.4 kWh" or "average daily consumption is 8.64 GJ" or "average daily usage is 2000 kcal", it's the same thing.
You're right, there's not. However, average daily power is useless in the context of the power output you need at a given time. If you want to find out how much you charge people for a month for power roughly, sure, its a decent number, but it doesn't say anything about the power load on the grid at a certain time of the day. The same applies with human beings.
Ok, let's rephrase that then. "The average daily food energy consumption of a mostly sedentary adult human is roughly the same as the daily electric energy consumption of a 100W lightbulb constantly turned on". Which, to me, says exactly the same thing as the initial post, namely, "a human needs about as much energy to live as it takes an old style lightbulb to function". |
Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.07.08 17:18:00 -
[15]
You got the main idea from the start, you realize it's ROUGHLY accurate, you're being needlessly picky. |
Akita T
Caldari Navy Volunteer Task Force
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Posted - 2011.07.11 02:56:00 -
[16]
Originally by: Gerdan BloodELF All I can think of reading this thread is the matrix and how best to feed the enslaved human population for as cheap and efficient as possible
http://news.bbc.co.uk/2/hi/7559150.stm
_
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