Guest CreatnScienc Posted July 9, 2005 Share Posted July 9, 2005 I am new at sciences and physics, so please bear with me. I would like to know how fast air would have to travel at normal atmospheric pressure to create heat. I cannot find the answer anywhere. Link to comment Share on other sites More sharing options...
Callipygous Posted July 9, 2005 Share Posted July 9, 2005 i think pretty much any movement of anything in any substance creates heat. the question is how much. Link to comment Share on other sites More sharing options...
ydoaPs Posted July 9, 2005 Share Posted July 9, 2005 oddness is that fast air cools surfaces. breath on your hand then make the air go faster over your hand. or puncture a CO2 cartrige Link to comment Share on other sites More sharing options...
Guest CreatnScienc Posted July 9, 2005 Share Posted July 9, 2005 I know that air will "cool" a surface, but only to a certain point. Once the air reaches a certain speed, the air particles start creating friction to the point of creating heat. Obviously the speed depends on atmospheric pressure. I am not sure about this, but, I think I heard somewhere that the air would have to travel faster than the speed of sound, which I found out to be 761 MPH (or, 1225 Kph), but that seems quite excessive. Link to comment Share on other sites More sharing options...
Lance Posted July 10, 2005 Share Posted July 10, 2005 oddness is that fast air cools surfaces. breath on your hand then make the air go faster over your hand. or puncture a CO2 cartrige This has nothing to to with moving air. The former is caused by water evaporating and absorbing heat. The latter is caused by the CO2 rapidly expanding and absorbing heat. Link to comment Share on other sites More sharing options...
d22k Posted July 10, 2005 Share Posted July 10, 2005 This has nothing to to with moving air. The former is caused by water evaporating and absorbing heat. The latter is caused by the CO2 rapidly expanding and absorbing heat. you beat me too it. in answer to the OP's Q, any friction no mater how slight will produce heat and sound. Link to comment Share on other sites More sharing options...
swansont Posted July 10, 2005 Share Posted July 10, 2005 I know that air will "cool" a surface' date=' but only to a certain point. Once the air reaches a certain speed, the air particles start creating friction to the point of creating heat. Obviously the speed depends on atmospheric pressure. [/quote'] In most of the examples of fast-moving things being heated it's not friction, but ram pressure that causes the heating. The air can't get out of the way (supersonic travel) and the compression causes the heating, opposite of the CO2 expansion example. Link to comment Share on other sites More sharing options...
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