【英语时差8,16】重空气

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Heavy air on this Moment of Science.

 

Here's an oxiny question: does air weigh anything?

 

At first it might seem preplexing, on the one hand, air just seems floating, I mean, to say something is as light as air is to say its weighlessness, is isn't? 

 

But then, a strong wind can pull floations down and set things fly. So air isn't exactly nothing. Air doesn't affect to have a weight and here's a simple way you can prove it.

 

You'll need two identical balloons, a string and a doul. Test the uninfeded balloons to either end of the doul, test the string to the center of the doul and then hanging it from something. If the baloons are very nearly identical, the doul should hang evenly without tipping to either side. You now have a basic scale. Next, inflate¹ one of the balloons by blowing into it, what happens? You bet, the side with inflated² balloon hangs lower than the other side. You have demonstrated that air has a weight.

 

The simply demonstration³ sometimes confuses people. Why does a balloon filled with air fall? When it's only surrounded by air, why doesn't it just remain where it is? The answer lies in density⁴. Any fluit anything that has a greater of density than its surroundings will sink. When you blow the baloon, you are increasing its overall density by forcing air inside it. That's because the air inside the baloon is under greater of pressure than the air outside. It's being squeezing entirely⁵ by the sides of the balloon. Greater pressure it's greater of density so the heavy air inside the balloon will fall.

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