Timeline for Why am I not burned by a strong wind?
Current License: CC BY-SA 3.0
19 events
| when toggle format | what | by | license | comment | |
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| S Jul 14, 2015 at 16:38 | history | suggested | CommunityBot | CC BY-SA 3.0 |
average velocity would be 0; average speed is what they meant in this context
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| Jul 14, 2015 at 16:27 | review | Suggested edits | |||
| S Jul 14, 2015 at 16:38 | |||||
| S Feb 5, 2014 at 8:30 | history | suggested | Mohammad | CC BY-SA 3.0 |
problem with mathjax
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| Feb 5, 2014 at 8:00 | review | Suggested edits | |||
| S Feb 5, 2014 at 8:30 | |||||
| Feb 4, 2014 at 14:59 | comment | added | luk32 |
I think you confused the instantaneous velocity with average velocity. In the 1st sentence. Their chaotic thermal movement is 500 m/s. When you use the derivative formula, or the usual one (delta r)/(delta t) with small delta t. Average is for large delta t and this is the relatively small value perceived by us. Similar effect is observed in a conductor when there is an electrical current. The average speed of electrons are in orders of cm per second if I recall correctly (or slower), its called drift velocity.
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| Feb 3, 2014 at 20:28 | comment | added | TypeIA | @tpg2114 +1 for correctly attributing aerodynamic heating... many (most?) people incorrectly believe it's due to friction with the air, which is only a minor contributor compared to the heat generated from compression. | |
| Feb 3, 2014 at 14:52 | comment | added | jwenting | @tpg2114 another reason it had to refuel was that it did not normally take off with full tanks. | |
| Feb 2, 2014 at 20:05 | history | edited | Mark Eichenlaub | CC BY-SA 3.0 |
I wasn't saying air is N2 and O2. I was referring specifically to the N2 and O2 in the air. Other constituents have different speeds, so I was singling those out.
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| Feb 2, 2014 at 19:59 | history | edited | Řídící | CC BY-SA 3.0 |
formatting; added links; added "mostly"
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| Feb 2, 2014 at 2:25 | comment | added | Mark Eichenlaub | @Anixx As the answer states, I am referring to energy density, not velocity. | |
| Feb 2, 2014 at 2:19 | review | Suggested edits | |||
| Feb 2, 2014 at 2:27 | |||||
| Feb 2, 2014 at 2:06 | comment | added | Anixx | 50 is 10% of 500, not 1% | |
| Feb 1, 2014 at 23:57 | comment | added | tpg2114 | @andyholaday It's effectively the same thing -- the kinetic energy of the molecules from the air must go somewhere when the air is brought to rest against the surface of the body. That somewhere is into thermal energy (and possibly into chemical or electronic modes). So the heating of air from compression is due to the conversion of kinetic energy of the molecules being converted to thermal energy. | |
| Feb 1, 2014 at 23:55 | comment | added | tpg2114 | @lionelbrits It leaked so much fuel that it would take off, fly supersonic to heat up the skin so the leaks closed, and then had to be refueled because it used up it's entire fuel load just doing that. | |
| Feb 1, 2014 at 23:42 | comment | added | andy holaday | I think this is a great answer, but I'm questioning the part about fast-moving objects like the SR-71. Is the heating effect really due to high velocity relative to the motion of air molecules? Or is it due to the extreme compression of air in front of the object (ideal gas law comes to mind). Or are these kind of saying the same thing? | |
| Feb 1, 2014 at 21:32 | comment | added | Jinx | I thought it might have something to do with molecules speed vs wind speed | |
| Feb 1, 2014 at 21:31 | vote | accept | Jinx | ||
| Feb 1, 2014 at 20:59 | comment | added | lionelbrits | I think the SR-71 actually leaked fuel on the runway, and circulated fuel beneath the skin to cool itself. | |
| Feb 1, 2014 at 20:55 | history | answered | Mark Eichenlaub | CC BY-SA 3.0 |