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| Source: abetterchemtext.com |
Monday, June 3, 2013
Air Pressure and Straws
Okay, so this is probably going to seem kinda nerdy, but hey, I'm an engineer, I think about these kinds of things. Thought of this one the last time I was at a restaurant. Anyways, you know how when you suck on a straw in a drink you're rewarded with some refreshing liquid in your mouth? Well, you're not actually the one responsible for that mouthful of drink, not directly; it's all about air pressure. We all know that the air around us presses on everything. Well, it's pressing on the surface of that drink in your cup. So when you suck on the straw, all you're doing is creating an area of low pressure inside the straw so that the air can push the drink up the straw into your mouth. You're not exerting a force on the drink at all; you're just reducing the force on the air inside the straw so that the air outside the straw, which is constantly pushing on the drink, is now stronger and pushes your drink up the straw. That's a lot less satisfying, isn't it? It's not like your actions have a direct result on the drink; without the air pressure, you could suck on that straw for all you're worth and nothing would happen. You're not pulling the drink into your mouth, much as you might think you are. It's rather disappointing! You aren't getting a direct result like when you pull on a wagon; there, you're directly responsible for its movement. Here, the air is doing the work of pushing, you're just making it possible. Think of that the next time you drink out of a straw!
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My daily physics lesson at lunch time....sigh. ;)
ReplyDeleteHaha, always happy to share a little physics. Even if it does go in one ear and out the other for some people... ;) But you gotta try, right?
ReplyDeleteSo you're telling me they don't use straws to consume their beverages in the space station? neat!
ReplyDeleteExcellent observation! I actually had to think about this one for a bit! Okay, so in the vacuum of space, you couldn't use a straw. However, since there is air in the space station and therefore air pressure, they could theoretically use straws to drink from a glass of water; but since there's practically no gravity to keep the water inside the glass, they still can't. However, they could use straws to drink out of enclosed packets which keep the beverage from floating around; and that's how they do it, I believe.
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