Explore: Is Air Really There?

  Try This!

Tear a small corner from a piece of tissue paper or paper towel; place it just inside the mouth of an empty plastic water bottle.  Try to blow the piece of paper into the glass.  Did you notice what happens?  Watch the video to see a similar demonstration.

This simple task is not as easy as you may have thought because the glass is not actually empty.  The glass is full of AIR!  Air takes up space, and even if we cannot see it, we can tell it is there when we try to move something into it.  Air is also always exerting pressure—pushing on everything it has contact with. 

When you try to blow the paper into the glass, the paper actually gets pushed out because the air you are blowing in causes the air inside to "overflow" and come out, pushing the paper out with it.  This is just as if the glass is full of water and you tried pouring more water into it. 

Air has mass and volume.