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.

長久以來，吸管是人類用來幫助自己解渴的最基本的工具之一。吸管非常普遍，以至于人們很少思考它們的工作原理。大多數人認為吸管是將液體拉上來、通過管子抵達口中。但是，吸管背后的科學原理稍微復雜一點。

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，你得先理解氣壓（或大氣壓強）的概念。氣壓是我們四周空氣的重量所施加的壓力，不過我們既看不到也感覺不到氣壓。氣壓會施加在所有物體的表面，包括杯子里的任何液體。當吸管被置于一杯水里時，施加于吸管內、外水面上的氣壓是相等的。然而，空氣會隨著液體的吸入而從吸管中被排除，這會使吸管內的壓力比吸管外的小。吸管外較大的壓力接著會將吸管內的液體往上推至口中，直到內外的壓力值再度相等。因此，液體不是簡單地被吸管吸起來，而是被壓力值的差異推進。

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.

如果吸管依賴大氣壓強來運作，那就帶來了一個問題：吸管在外太空可以用嗎？外太空幾乎是真空狀態，沒有足夠的力量能推動液體。因此，在太空站人造大氣之外的外太空使用吸管是行不通的。幸好我們的星球有穩定的大氣，能讓我們使用吸管來飲用所有我們喜愛的飲品。

Word Bank

quench" v. 解（渴）；止（渴）

exert" v. 運用；行使；施加

suction" n. 吸；抽吸；吸出