Fluid Pressure and Temperature
Name: Kailey Joy M.
Date: Saturday, April 20, 2002 8:17:44 PM
When I exhale, why is my breath warm when my mouth is
wide open but is cold when my lips are puckered?
Whenever a material expands, it cools of. IF you breathe with your mouth
wide open, the air from your mouth comes out just as it is in your lungs.
There is no compressing or expanding. It is warm. When you pucker your
lips, the breath is compressed within your mouth: the air atoms are
squeezed more tightly together than usual. As it leaves your mouth, the air
expands. It gets less tightly packed. This results in a cooling. The more
strongly you blow, the more tightly packed becomes the air in your lungs and
mouth. Blowing harder then results in more expanding and cooling as the air
Dr. Ken Mellendorf
Illinois Central College
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