|Office of Air Quality
February 24, 1997
To show students the affects of air pressure.
Acquire data through the senses. (3)(B) classify matter and forces, organisms, actions, and events from the environment according to similarities and differences.
Show the students a bottle that has a mouth that is too small for an egg to pass through.
The student will be able to identify air pressure and how it affects objects.
Two hard boiled eggs, matches, paper towel, small jar (opening large enough to let the egg almost pass through), thin wooden board (a strip of thin plywood or paneling that is 2 ft. long by 3 to 4 inches wide.)
Air pushes on all surfaces that it touches. Air at sea level exerts a pressure of approximately 14 1/4 pounds per square inch. Therefore, on a piece of paper 10 inches square the air exerts a pressure of 1,450 pounds on the top surface. The same pressure is also exerted on the opposite surface, counteracting the pressure on the other side.
A. Begin class with the "Egg in the Bottle."
As the air was heated, it began to expand. Some of the air escaped causing the egg to wobble. When the fire was extinguished, the air began to cool and contract. The egg seals the bottle. There is less air in the bottle causing unequal pressure to occur between the air in the bottle and the air outside the bottle. The greater air pressure on the outside pushes the egg into the bottle equalizing the air pressure inside and outside the bottle.
B. Demonstrate the "Weight of Air."
The paper will not move. If you hit hard enough, the stick will break. This is due to the air pressure that is exerted downward. Since the paper is flat against the board and table, no air is beneath the paper to counteract the pressure from above.
Martha Suarez, Stephen F. Austin University Nacogdoches TES Course, 1994
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