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What are those gas molecules doing? mostly just bouncing around. –off each other, off the walls.
How fast are they moving? fast. really fast. usually over a thousand miles per hour (you are being pelted by molecules right now).
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but that speed is only for individual molecules; the gas as a whole has no great speed or direction because the molecules bounce off each other randomly in every possible direction.
How many molecules are in any given space? a lot! the room you're sitting in has about a gazillion gas molecules in it (the box in the above animation represents an area much tinier than a grain of sand).
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