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so lets say you're walking down the street

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and im going to draw you here and you decide to do a little experiment.

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you take a deep breath as you're walking and you decide to blow out a cardboard tube

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something like that

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lets say its like a toilet paper roll

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and so you blow out through it

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and here in this toilet paper roll

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the length is, lets call, l and the radius and i'll call it r

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and you know a toilet paper roll is, lets say about 2 cm

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radius. That may not be exactly right but lets just assume that.

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And you do this and you find that it is so easy to do.

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Very easy to take one breath of air and blow it out an blow it out of a cardboard tube