The results of the experiment prove that the newspaper is more difficult to lift when it is spread out over a large area, yet the weight of the folded and flat newspaper remain the same. What other force is exerted on the newspaper that could account for these differences? The answer is as simple as the air we breathe. It is the pressure of the air pushing downward on the newspaper that prevents the paper from rising.
It might be useful to picture a giant column of air resting on top of the newspaper. This column of air is 250 miles (402 km) tall! This column of air above the newspaper pushes down with a force of 14.7 pounds of pressure per square inch (this is at sea level). In other words, each square inch of the newspaper has 14.7 pounds pushing down on it. So, if you know the area of the newspaper, you can calculate the total amount of pressure pushing downward on the paper. Let's say that the newspaper dimensions measure 20 inches by 30 inches. The total area is 20 inches X 30 inches = 600 square inches. If each square inch has a force of 14.7 pounds pushing on it, then 600 square inches X 14.7 pounds per square inch = 8,820 pounds! That's the equivalent weight of two large automobiles. It's no wonder that the newspaper stayed in place at the moment when you hit the stick. Smoothing down the newspaper with your hands prior to hitting the stick is a crucially important step. You want to make certain that there is no air under the newspaper that might help it to lift up when you strike the stick.
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