[turmoil]

Click

A gallon of gasoline is about 32,000 kcal. 1 kcal = 1 Nutritional Calorie

And we wonder why heavy vehicles get such low mileage...

Interestingly, this sandwich weighs about what a gallon of gas weighs (6.5 lbs)

[evilmonkeyspanker]

That is the most discusting sandwich I have ever seen.

[nocar]

Yes, it is interesting to compare gasoline/diesel enery for cars with food energy. We often talk about "thirsty" vehicles, which sort of make us think of gasoline as beverage, beer or soda perhaps. We really should think about "hungry" cars. Gasoline and diesel both compare to butter, margarine or cooking oil on terms of energy per volume. A gallon of butter or a gallon of cooking oil is a lot of food.

nocar

[turmoil]

That is the most discusting sandwich I have ever seen.

Agreed.

Yes, it is interesting to compare gasoline/diesel enery for cars with food energy. We often talk about "thirsty" vehicles, which sort of make us think of gasoline as beverage, beer or soda perhaps. We really should think about "hungry" cars. Gasoline and diesel both compare to butter, margarine or cooking oil on terms of energy per volume. A gallon of butter or a gallon of cooking oil is a lot of food.

yeah. According to the chart 154 tbsp of canola oil is 18,432 Calories. If we wanted to find out how many Calories a gallon of canola oil has (256 tbsp), we could do a little fractional algebra.

154 tbsp = 18432 Calories

256 tbsp = X Calories

cross multiplying, etc gets us

18432 * 256 / 154 = ~30640 Calories

Which means that canola oil is almost as energy dense as gasoline. Oil is oil is oil it seems. If you were to burn grease, I'd assume that relative carbon would be released.

[0mar]

i just got very very hungry...

[mgibbons19]

So a gallon of gasoline has 30,000 calories? 10 active days' worth of food?

[turmoil]

So a gallon of gasoline has 30,000 calories? 10 active days' worth of food?

remember that gasoline is not as energy dense as crude oil. but yes i've seen numbers that range from 31,600 - 36,000, or 12-14 days worth.

edit: a couple corrections

[mgibbons19]

ok thanks

[Caoimhan]

So how energy efficient is the human body?

A gasoline engine is only about 25% efficient, meaning it will turn 32,000 kilocalories in that gallon of gasoline into approximately 33.5 megajoules of work.

Just idle curiosity.

[turmoil]

So how energy efficient is the human body?

A gasoline engine is only about 25% efficient, meaning it will turn 32,000 kilocalories in that gallon of gasoline into approximately 33.5 megajoules of work.

Just idle curiosity.

The How Stuff Works site has some great info but I'll chip in.

It depends on what the body is doing. One thing it has to do all the time is maintain a body heat of 98.6 F, and even after millions of years of mammalian evolution, it probably requires a chuck of our energy intake.

If you ask, how efficient is the body at <task>, then we can take calories burned and ask, what percent of intake was used in this task? In the bicycle gas milage thread we discovered that efficiency can vary a lot from person to person based on fitness.

But the body's purpose is to acquire, process, and store chemicals to maintain a fat storage, body heat, and electrical brain function.

[syncline]

The basic cycle of aerobic respiration, which creates ATP out of ADP, is about 40% efficient.

That doesn't mean that the body can turn 40% of food energy into useful work when doing something like shifting rocks, though, since the ATP must be cycled back to ADP in the muscle and this has an efficiency that varies depending on the type of exercise, the type of muscle, and the health of the worker.

This varies a LOT but a ballpark figure is the overall (work out) / (chemcal energy in) is around 20%.

[Caoimhan]

Cool... thanks for your answers.

From a biologist's perspective, and at the most basic level, the purpose of food is to help us survive long enough to pass our genes on to the next generation... as many times as possible, before we die.

Basically, we eat so that we can reproduce. There's a reason why many of our mating rituals include going to dinner first.

But if I made a sandwich like that for my date, I think she'd run away screaming.

[turmoil]

did a little more research and found the page below with this google search

http://www.cptips.com/energy.htm

The net result - only 25% of the Caloric energy in the food we eat is actually used to power the mechanical work of the muscle cells.

Ironically, that is equal to the efficiency of the ICE! But I bet that is an avg and like we said it probably varies a lot when you get into the details. Also, the food we eat is not pure energy like gasoline.

Also, two links below that one is a page on Bird metabolism and thermoregulation. Quite interesting.
http://www.ornithology.com/lectures/Metabolism.html

[EnergySpin]

I knew a person who used to eat like that.
He made one final stop at the cemetery in his mid 30s....
That disgusting thing had 1/2 lb of butter!

[Licho]

Nuclear powerplant that supplies my home has power output of 2000 such cookies:

per second!!

And my AAA battery has less energy than one piece of cookie..

[Devil]

OK, you think, say, 15 days worth of food = 1 gallon of fuel.

Double your food intake, drive your car to the end of a 30 km long flat stretch of road. Get out of the driver's seat and walk round to the back of the car and start pushing, accelerating the vehicle to 60 km/h in, say, 10 seconds. Keep pushing it at this speed. Stop after 2 km and repeat the following day and so on, until you reach the end. If you have done that without gaining or losing weight, then you know all those extra calories you have consumed were equivalent to a gallon of gas. If, on the other hand, you have a fatal heart attack on the first day or you fall flat on your face because you are unable to push the car at the required speed, this will prove nothing at all.

[Caoimhan]

If you can push your car to 60 km/h in 10 seconds, please join the Olympic team!