Science of the Simple Drinking Straw小小吸管的“魔力”

Straws are one of the most basic tools that humans have been using for a long time to help quench our thirst. They are so common that people rarely think of how they work. Most assume that straws work by pulling liquid through them into the mouth. However， the science behind straws is a little more complicated.

长久以来，吸管是人类用来帮助自己解渴的最基本的工具之一。吸管非常普遍，以至于人们很少思考它们的工作原理。大多数人认为吸管是将液体拉上来、通过管子抵达口中。但是，吸管背后的科学原理稍微复杂一点。

To understand how straws function， you have to first grasp the concept of air pressure， or atmospheric pressure. Air pressure is the force exerted by the weight of the air surrounding us， though we can neither see nor feel it. It presses on the surface of all objects， including any liquid inside a cup. When a straw is placed in a cup of water， the air pressure acting on the water both inside and outside the straw is equal. However， air will be removed from the straw with the suction of liquid， making the pressure inside the straw lower than the pressure outside. The greater pressure outside the straw will then push the liquid inside the straw up into the mouth until the pressure levels are equal again. Thus， rather than only being sucked up by a straw， the liquid is also pushed up by differences in pressure levels.

要了解吸管如何起作用，你得先理解气压（或大气压强）的概念。气压是我们四周空气的重量所施加的压力，不过我们既看不到也感觉不到气压。气压会施加在所有物体的表面，包括杯子里的任何液体。当吸管被置于一杯水里时，施加于吸管内、外水面上的气压是相等的。然而，空气会随着液体的吸入而从吸管中被排除，这会使吸管内的压力比吸管外的小。吸管外较大的压力接着会将吸管内的液体往上推至口中，直到内外的压力值再度相等。因此，液体不是简单地被吸管吸起来，而是被压力值的差异推进。

If straws rely on atmospheric pressure to function， it begs the question： Can straws work in outer space？ Space is almost like a vacuum where there is not enough force to propel liquid. Therefore， using a straw in outer space outside the artificial atmosphere of a space station would be impracticable. Luckily， our planet has a stable atmosphere that allows us to use straws for all of our favorite drinks.

如果吸管依赖大气压强来运作，那就带来了一个问题：吸管在外太空可以用吗？外太空几乎是真空状态，没有足够的力量能推动液体。因此，在太空站人造大气之外的外太空使用吸管是行不通的。幸好我们的星球有稳定的大气，能让我们使用吸管来饮用所有我们喜爱的饮品。

Word Bank

quench" v. 解（渴）；止（渴）

exert" v. 运用；行使；施加

suction" n. 吸；抽吸；吸出