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Sturgeon's House

I Learned Something Today


LostCosmonaut
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The Puget Sound area was first settled by Americans because the Oregon Territory was racist against George Bush.

 

Partially true. But yeah, the area that would be the Washington territory was more accepting of guys like George Bush and George Washington who settled Centralia.

 

Fortunately, we have footage of some of Washington's first white pioneers welcoming their new neighbors.

 

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That's kind of funny because one of the wise tales that my friends and I were admonished with/joked with each other in sixth grade through middle school was that if you masturbated too much, hair would grow under your fingernails. 

 

*The joke being that you'd then laugh at the people who then looked at their fingernails*

 

Those women must be very lonely.

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Today, after a truly chastening and humiliating experience, I thought to myself "I am so behind the power curve right now."  And then I thought to look up the origin of that phrase.  Turns out it's from aerospace.

 

45.gif
 

(LostCosmonaut is rolling his eyes 'cause he learned this shit in kindergarten)

A plane is slowed down by two types of drag; parasite drag, which is caused by bits of the plane sticking out into the airstream and colliding with air molecules, and induced drag, or vortex drag as it's increasingly now called.  Vortex drag is a side-effect of generating lift.

Parasite drag is caused by all sorts of sub-components; surface friction, interference drag, form drag, and if you're in a pointy-nosed go-fast mach snot plane with afterburners, by wave drag (which is also called compressibility in old-timey sources from back when they didn't really understand it).  Parasite drag increases with airspeed, because all the bits of the airplane are colliding harder with the air molecules the faster they go (essentially; this is a simplification).

Vortex drag actually goes down the faster the plane goes, because the faster the plane goes the more air its lift-generating bits (wings, blended wing body shapes, canards, et cetera) come in contact with, the less of an angle of attack they need, and the less of a big, swirly, power-robbing vortex the plane makes:

 

IDXk0oV.jpg

 

So since vortex drag is going down as airspeed goes up and parasite drag goes up, there's going to be a point where they cross over.  That is the most efficient speed for the aircraft to fly at.

 

Now, a bit of dimensional analysis.  Drag is a force, or mass times acceleration.  Energy is force times a distance.  Power is energy over time.  So power is also force over velocity.  So airspeed squared times drag coefficient times air density the frontal area of the plane the mass of the airplane equals power (yes, I'm skipping some steps here).  So we can think of the drag curve as a power curve.

The left side of the power curve is not a happy place to be, because you end up using more power to fly slower.  You're stuck in this Red Queen's race where your plane's engine needs to work harder and harder just to slow down because the airfoils are operating at much lower speeds than they were designed for.

 

This is why the Concorde was hamstrung when it got stuck in traffic patterns outside big airports.  Concorde was optimized to go fast, and it's power curve peaked way, way faster than it was going when ATC stuck it in a holding pattern.  It was actually burning more fuel just to putter in circles around the skies of NYC or London than it would if it were making mach waves going across the Atlantic.

 

And that is exactly how I feel today.  I need to work harder and harder just to go slow.

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Discussing chem homework today with Tekky, we stumbled onto the principle of how IR spectroscopy works.

 

Chemical bonds between atoms in molecules act like springs.  They have a fundamental frequency that they vibrate at.  If more energy gets put into the bond the amplitude of the vibration will increase, but the frequency will remain the same.

 

Molecules will absorb IR energy especially well if the frequency of the IR energy exactly matches the fundamental frequencies of these bonds.  IR light shone through a compound will show sudden increases in absorbency in these wavelengths:

1DYY9Hi.gif

 

This makes IR spectroscopy very useful, because not only can it match unidentified compounds to known spectroscopic fingerprints, but it can also identify the functional groups and therefore the likely properties of an unknown compound.

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Discussing chem homework today with Tekky, we stumbled onto the principle of how IR spectroscopy works.

 

Chemical bonds between atoms in molecules act like springs.  They have a fundamental frequency that they vibrate at.  If more energy gets put into the bond the amplitude of the vibration will increase, but the frequency will remain the same.

 

Molecules will absorb IR energy especially well if the frequency of the IR energy exactly matches the fundamental frequencies of these bonds.  IR light shone through a compound will show sudden increases in absorbency in these wavelengths:

1DYY9Hi.gif

 

This makes IR spectroscopy very useful, because not only can it match unidentified compounds to known spectroscopic fingerprints, but it can also identify the functional groups and therefore the likely properties of an unknown compound.

Spectro isn't all that useful with mixtures though.

 

Which is why separation (HPLC and the like) and NMR get used a lot as well.

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And the reason why it does that is quantum theory.

Because all of chemistry is just applied physics.

And in all of science, there is only physics, the rest is stamp-collecting. (Rutherford)

Quotes like that are why physicists have such a sterling reputation amongst other scientists.

 

Because really, come do my job for me and see how easy this shit is.

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