Another Day, Another Glimpse at Air

Arnaldo Cruz Betancourt

The other day, a thought came to my head.  This thought, for the level of understanding that I had at that time, seemed to have no answer.  But now the thought have been answered and without further ado that was:  “If we know that friction is present when two objects rub each other and friction transforms into heat energy.  Then, does air friction transforms into heat energy?”

Friction is defined as a force that resists the relative motion or tendency to such motion of two bodies or substances in contact.  This opposing force, in theory, “creates” heat no matter what two surfaces are in contact and consequently air friction does transform in heat energy.  For example, have you ever try to put your hand outside of a moving car?  At the instant you put the hand outside you feel a force pushing your hand to the back of the car and between that force and your hand exists friction, friction between the hand and the air that rushes by.  When the hand is outside, you feel the hand is getting colder because of the temperature of the wind but you get your hand inside the vehicle what you feel is this rare feeling of the coldness of the air and at the same time the heat of the friction that this force produced.  Remembering the law of conservation of energy that states that energy is neither created nor destroyed it can only be transformed from one state to another (from kinetic energy to heat energy). 

Another more convincing example is, have you ever wonder why an airplane can’t depart if the outside conditions are icy and the temperature is cold? Well the answer is very simple, it is because the turbines of the airplane are frozen and the runway conditions aren’t appropriate to the plane to depart (icy runway).  But what if we add an additive to the turbines for them to de-froze and add another additive to the runway to eliminate the ice in it, then the plane can depart.  Getting back to the point, when the airplane is flying at a high altitude, the outside air temperature is colder than the temperature at the airport just mentioned and we can’t simply add an additive to the plane when the plane is airborne.  Then, why the plane turbines don’t freeze?  This is attributed to the force of friction present between the fluid of the air and the solid wing.  Although the outside air is cold, the heat transformed from the force of friction counteracts the freezing component of air making the plane and the wings to work on proper work conditions in which the air temperature is offset by the heat caused by the friction. For which this quote can summarize the two examples presented: “A regular commercial airplane, after landing, will feel cool to the touch. But the Concorde jet, which flies at twice the speed of sound, will feel hotter than boiling water.”

In light of these examples, we can conclude that friction is a force in which at a result enables different types of energy, for instance as mentioned before, heat energy.  The nature of friction is the one responsible that an airplane can work properly, the movement of a car and even the less expected, how humans move. For whichever the question is, the answer is there just for the human being to discover.  Sometimes complicated, sometimes simple the answer may be but with the help of the powerful tool of physics, that has the ability to explain everyday phenomenons, by simple, clear explanations and mathematical equations we can explain such phenomenon.

References

http://www.parentcompany.com/creation_explanation/cx2b.htm

http://www.answers.com/topic/friction

http://www.scienceclarified.com/A-Al/Aerodynamics.html

http://www.scienceclarified.com/A-Al/Aerodynamics.html#ixzz1Ky13nFzU

http://www.allstar.fiu.edu/aero/fltmidfly.htm

Giancoli, Douglas C. Physics for Scientists & Engineers with Modern Physics. 4th ed. Vol. 1. Upper Saddle River, N.J: Prentice Hall, 2009. Print.