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Name: Low
Status: student
Grade: 9-12
Country: US
Date: Winter 2011-2012


Question:
Why does air tend to rush in a narrow corridor or a door?



Replies:
Hi Low,

Like the Venturi of a carburetor of the older cars where the air rushes through a narrow passage, the pressure is higher.

This is related to the relationship that Pressure = Force / Area. The cross section of the narrow passage has a smaller area. If we assume the force of the air is constant, then the relationship follows that the pressure is higher.

That's the essence of why the air rushes.

-Alex Viray


There is a simple "general" answer; however, the details may be much more complicated. Air will "rush", that is flow, from a region of high pressure to a region of low pressure. That is the easy part, always true. The more difficult part is why in any given set of conditions there is a pressure difference from one place to the other. It can be a temperature difference, a secondary flow of air -- for example a gust of wind -- and many other possible causes. But the common factor is a pressure difference that will tend to equalize causing the rush of air.

Vince Calder



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