Getting back to basics today. Lately I’ve been focusing solely on science news stories and neglecting some of the cool basic science of our everyday lives. I decided to start with atmospheric pressure because it influences so much without us ever realizing it.
We don’t normally think of air as having any weight, but it does. The weight of our atmosphere is 14.7 pounds per square inch. We don’t feel that weight because our bodies are generally in equillibrium with the outside (more on this a little later). But the buddy we didn’t know we had is always looking for a difference in pressure to exert some force. Over the next couple of comics I’ll touch upon some other pressure-related phenomena, but for today you get drinking straws!
The misconception is that, when you drink through a straw, you’re sucking liquid through the straw and into your mouth. What’s really happening is that you’re creating a difference of air pressure inside your mouth, which is equalized by liquid flowing in. It all goes back to breathing, where your diaphragm (a muscle stretched across your rib cage) contracts, increasing the volume of your chest cavity, and the void is filled by air rushing into your lungs.
“Maki, in the comic you said that you can’t drink from a sealed container. Then what is this?”
Pouches like this still work because the container itself is deformed by the surrounding air pressure pushing on it, and subsequently pushing the liquid out. But we’ll talk more about the crushing power of our own atmosphere in another comic.
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