Atmospheric pressure is the force per unit area exerted against a surface by the weight of air above that surface in theEarth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location. Similarly, as elevation increases there is less overlying atmospheric mass, so that pressure decreases with increasing elevation. A column of air one square centimetre in cross-section, measured from sea level to the top of the atmosphere, has a mass of about a kilogram and a weight of 63N (and a column one square inch in cross-section would weigh about 14.7 lb).
1. One or two full sheets of an ordinary newspaper.
2. A stick of pine wood (ruler, paint stick, wooden pencil)
1. Place the stick on a table with a smooth surface and let it protrude over the edge about 8 cm.
2. Ask students to hypothesize what will happen when you hit the stick.
3. Strike it and let students catch the flying stick.
4. Place the stick back on the table like in point 1, and cover it with the newspaper flush with the
edge of the table.
5. Ask students to now hypothesize what will happen if you hit the stick now? (anticipated answer:
' the paper will fly up' or 'paper will tear')
6. Smooth down the paper with your left hand and strike the protruding end of the stick with your
fist (a sudden sharp blow): The stick will break.
7. have students hypothesize how much stick you could leave out each time before the pressure is
not enough to hold the paper down.
Photographs and MoviesVideo with background information on air pressure and newspaper strength
Reference 1 (give the title of the page and insert a link. Don't just paste URL)