Air In, Air Out
A big fan moves air from left to right. As the fan moves
the air out of the left-hand chamber, it creates an area of lower
pressure. Air at the normal air pressure constantly rushes in through
the hose to refill the box, working much like the vacuum cleaner
you use on your carpet.
Discover how moving air changes the shape of the landscape!
Watch as the air blown by a fan moves and rearranges sand inside
the chamber. Notice that the sand always creates patterns, not smooth
No ammunition needed except a gentle slap on the rubber
backing of the "cannon." After you strike, watch the flutter
disks on the wallyou can see the "shape" of the
air puff striking the disks. A rubber mat with highlighted footprints
encourages you to stand in the path of the air puff to see what
it feels like to be hit with a cannonball made of air. Fire away!
Engineers who design heating duct systems for houses have
to figure out the number of turns and lengths of all the air passageways
before they can decide on the size of ducts and fans. They know
that before air can flow into a passageway, there must be an opening
at the end of the passage. Blow a foam ball through the maze--see
if you can change the direction of the ball by opening or closing
the doors. It's air-mazing!
Air flowing through a passage rubs along the inside of
the tube and its flow becomes turbulent. The longer (or more "wiggly")
the passage, the more energy air will lose. In this exhibit, you
and a friend can "race" two small balls by dropping them
through a pair of blowholes at the same time. Their paths are exactly
the same length: Which ball will arrive at the finish line first?
This is like juggling with air! See how many small foam
balls you can balance from the airstreams coming out of several
transparent tubes. Discover how to get the balls to drop down into
one tube and pop out of another, to balance more than one on a stream
of air, and to balance halfway up the tube.
We can't see air, but we can see its footprintswaving
flags, ripples on a pond, or swaying fields of wheat all indicate
that air is moving. Turn on the switch to this exhibit and direct
the air hose at the wall of flutter disks. The disks move in a "watery"
way because air flows a lot like water.
This is the entrance piece to the exhibit, and is a set
of fabric panels which flutter and flap as air blows upwards from
their base. A mesmerizing effect!
Until the curved sail was developed, mariners had to row,
row, row their boats against the wind. When moving air pushes directly
on the sail, it gives up some of its energy to the sail, and pushes
the sailboat along in the same direction. Give it a try yourself
by sailing model boats away from, across, and into the wind.
Air flowing through a tube pushes the ball along with it.
Put a short tube on one of the air "hydrants" and run
a ball through it. Or, add sections of the tube to make the path
longer. Does the ball behave differently? What happens if you cover
the end of the pipe with your hand?