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Speaker 1: Welcome to Brainstuff from house stuff Works dot com where

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

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Speaker 1: there a way to compare a human being to an

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Speaker 1: engine in terms of efficiency? It turns out that biological engines,

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Speaker 1: which is what the muscles in your body are, are

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Speaker 1: pretty amazing in terms of efficiency. To find out how efficient,

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Speaker 1: let's look at how many calories a person burns while

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Speaker 1: riding a bicycle. If you look on the web, you'll

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Speaker 1: find that a person riding a bicycle at fifteen miles

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Speaker 1: per hour or twenty four kilometers per hour burns about

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Speaker 1: point o four nine calories per pound per minute. So

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Speaker 1: a hundred and seventy five pound person burns five fifteen

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Speaker 1: calories in an hour, or about thirty four calories per mile.

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Speaker 1: That works out to twenty one calories per kilometer. A

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Speaker 1: gallon of gasoline about four eaters, contains about thirty one

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Speaker 1: thousand calories. If a person could drink gasoline, then a

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Speaker 1: person could ride about nine hundred and twelve miles on

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Speaker 1: a gallon of gas, or about three hundred sixty per leader.

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Speaker 1: Considering that a normal car gets about thirty miles to

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Speaker 1: a gallon that's pretty impressive. A human being on a

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Speaker 1: bicycle is about thirty times more efficient than a car

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Speaker 1: going down the road. To be fair, to keep in

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Speaker 1: mind that a car generally weighs a ton or more,

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Speaker 1: while a bicycle weighs only thirty pounds. Cars also travel

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Speaker 1: a lot faster than fifteen miles per hour, but it's

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Speaker 1: still an interest in comparison. Note also that people can't

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Speaker 1: drink gasoline. However, people can drink vegetable oil, which contains

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Speaker 1: nearly the same number of calories per gallon. The people

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Speaker 1: riding in a race like the Tour de France are

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Speaker 1: riding more like twenty five miles per hour. Because air

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Speaker 1: resistance rises very quickly with speed, they're burning about three

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Speaker 1: times more calories, something like a hundred calories per mile

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Speaker 1: in a hundred miles stage of the tour. A racer

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Speaker 1: might burn something like eight thousand to ten thousand calories

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Speaker 1: in one day, so they're getting only about three hundred

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Speaker 1: miles per gallon. The only way to replace those calories

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Speaker 1: is to eat a lot of food. For more on

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Speaker 1: this and thousands of other topics, is that how stuff

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Speaker 1: works dot com, and don't forget to check out the

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Speaker 1: brain Stuff blog on the house stuff works dot Com

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