Editing Two Can Two-Can (section)

== Why This Works ==

There is air all around us, and that air pushes on us all the time. This is called ''Air Pressure'', and we are using air pressure to make the cans move in this demonstration. When the cans are hanging in the still air, they experience air pressure equally on all sides, so they don't experience a push in any given direction. However, when air is blown between the cans with the straw, this moving air is no longer applying air pressure equally in all directions. Instead, the moving air is pushing mostly in a single direction (forward) and does not push as much on the cans (sideways). The still air on the other side of each can is pushing more on them than the moving air between them, so the cans get pushed to the center and towards each other!

When you blow at the cans without the straw, there are a few things that change. First, your breath is moving ''slower'' than when you used the straw, so the change in air pressure is smaller. Second, your breath doesn't blow directly in-between the cans, but rather is spread out more and hits the cans from the front. These two changes can affect the demonstration a lot, causing the cans to just bounce around from you blowing at them, instead of being pulled together.