*** 20th Anniversary: 2003 to 2023 ***
by Cindy chen
We did a science fair project about air pressure and testing if it is matter or not. It's for our grade 7 science fair project and is also for marks in school.
We did a few experiments on air pressure to prove that it's matter and not only what makes up the space around us and what we breathe.
Barry's Response - Webster's has this for "matter":
Material substance that occupies space, has mass, and is composed predominantly of atoms consisting of protons, neutrons, and electrons, that constitutes the observable universe, and that is interconvertible with energy.
That's pretty broad, and it easily includes air. What kind of matter is it? A pretty heavy one actually. All of the air combined weighs a little over eleven million million million pounds (5.1x1018 kg). That's kind of substantial.
It presses on the earth's surface and other objects at sea level with a force roughly equal to 2100 pounds per square foot, the weight of water 33 feet deep.
At a height of 18,000 feet, about half of the altitude where your average jet plane cruises, the pressure drops to half of its sea-level value. And the pressure keeps dropping off after that.
How high does the atmosphere go? Theoretically, infinitely, but somebody had to draw a line for it to end and outer space to begin. That person was Theodore von Kármán, and he set it at 100 km, which is 62.5 miles from the ground.
Here at the Kármán line, the pressure drops off to 0.3 millionths of the sea level pressure, and the air can no longer be used to fly planes. They would have to travel so fast they would be in orbit anyway.
So, yeah, air's an interesting matter as well. Search this site for more air information now.
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