WEBVTT - Is there a way to compare a human being to an engine?

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<v Speaker 1>Welcome to Brainstuff from house stuff Works dot com where

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<v Speaker 1>smart happens. I am Marshall Brain with today's question, is

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<v Speaker 1>there a way to compare a human being to an

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<v Speaker 1>engine in terms of efficiency? It turns out that biological engines,

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<v Speaker 1>which is what the muscles in your body are, are

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<v Speaker 1>pretty amazing in terms of efficiency. To find out how efficient,

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<v Speaker 1>let's look at how many calories a person burns while

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<v Speaker 1>riding a bicycle. If you look on the web, you'll

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<v Speaker 1>find that a person riding a bicycle at fifteen miles

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<v Speaker 1>per hour or twenty four kilometers per hour burns about

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<v Speaker 1>point o four nine calories per pound per minute. So

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<v Speaker 1>a hundred and seventy five pound person burns five fifteen

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<v Speaker 1>calories in an hour, or about thirty four calories per mile.

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<v Speaker 1>That works out to twenty one calories per kilometer. A

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<v Speaker 1>gallon of gasoline about four eaters, contains about thirty one

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<v Speaker 1>thousand calories. If a person could drink gasoline, then a

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<v Speaker 1>person could ride about nine hundred and twelve miles on

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<v Speaker 1>a gallon of gas, or about three hundred sixty per leader.

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<v Speaker 1>Considering that a normal car gets about thirty miles to

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<v Speaker 1>a gallon that's pretty impressive. A human being on a

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<v Speaker 1>bicycle is about thirty times more efficient than a car

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<v Speaker 1>going down the road. To be fair, to keep in

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<v Speaker 1>mind that a car generally weighs a ton or more,

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<v Speaker 1>while a bicycle weighs only thirty pounds. Cars also travel

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<v Speaker 1>a lot faster than fifteen miles per hour, but it's

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<v Speaker 1>still an interest in comparison. Note also that people can't

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<v Speaker 1>drink gasoline. However, people can drink vegetable oil, which contains

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<v Speaker 1>nearly the same number of calories per gallon. The people

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<v Speaker 1>riding in a race like the Tour de France are

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<v Speaker 1>riding more like twenty five miles per hour. Because air

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<v Speaker 1>resistance rises very quickly with speed, they're burning about three

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<v Speaker 1>times more calories, something like a hundred calories per mile

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<v Speaker 1>in a hundred miles stage of the tour. A racer

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<v Speaker 1>might burn something like eight thousand to ten thousand calories

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<v Speaker 1>in one day, so they're getting only about three hundred

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<v Speaker 1>miles per gallon. The only way to replace those calories

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<v Speaker 1>is to eat a lot of food. For more on

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<v Speaker 1>this and thousands of other topics, is that how stuff

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