To Non-Java ALLSTAR Network Website
Please let me remind all of you--this
material is copyrighted. Though partially funded by NASA, it is still a
private site. Therefore, before using our materials in any form, electronic or
otherwise, you need to ask permission.
There are two ways to browse the site: (1) use the search button above to find specific materials using keywords; or,
(2) go to specific headings like history, principles or careers at specific levels above and click on the button.
Teachers may go directly to the Teachers' Guide from the For Teachers button above or site browse as in (1) and (2).
Because we cannot see air we may think of it as nothing, but you need only to stand in front of a fan or pedal your bicycle into the wind to know that air has substance. Air has weight because it is matter and is attracted by the Earth's gravity. Weight is explained in Figure 2-1a.
Notice that the direction of the atmosphere's weight is toward Earth's center, which is the center of gravity. Refer to the 1 inch x 1 inch x 60 miles column of air shown in Figure 2-1a. This column of air has a weight of 14.7 pounds. This is caused by gravity pulling all air molecules within the column toward Earth's center with that many pounds of force. It is the weight of the air which produces atmospheric pressure.
Always remember that WEIGHT is in one direction, while PRESSURE is in all directions.
Mass is the amount of material as shown in Figure 2-1b.
Use the button to return to the beginning of the chapter
Send all comments to email@example.com
© 1995-2017 ALLSTAR Network. All rights reserved worldwide.
|Funded in part by||From
Civil Air Patrol
Updated: March 12, 2004