Air can push!
You’re like a fish living at the bottom of the ocean. But you live at
the bottom of an ocean of air! Miles (kilometers) of water are piled up
above the fish, and miles of air are piled up above you.
All that air is heavy. It has weight. The weight of the air presses
against you, even though you don’t feel it.
Here’s how you can tell that air is pressing on things. You’ll need:
a drinking glass (it stiff cardboard
must be glass—not ~your\ sink\ or\ a~ paper or plastic) dishpan
water
Fill the drinking glass with water to the very top. Put the stiff
cardboard over the glass. Make sure the cardboard covers the whole
top.
Now, hold the cardboard in place with one hand and carefully turn the
glass upside down. Do this over a sink in case the cardboard slips. When
the glass is upside down, take your hand off the cardboard.
You may think the water will push the cardboard away and spill out. But
this won’t happen! The air beneath the cardboard weighs more than the
water in the glass. So the air holds the cardboard in place, because it
pushes harder against the cardboard than the water does.
