From the Greek meaning 'heavy with wine'
A blog devoted to science and reason
Written after a glass or two of Pinot Noir.

Tuesday, May 29, 2012

Flying Aircraft Carriers: Physics and Engineering in The Avengers

CREDIT: Marvel Studios

I saw the Avengers on Memorial Day.  Awesome movie, and if you've read one of my early blog posts, Transformers 3 - Dark of the Moon, you might guess I sometimes think about physics during the movie.  One thing that caught my attention was the flying aircraft carrier.  What would it take to make one fly?

Thanks to Wikipedia, I found some specifications for a modern US navy supercarrier.  They are 333 meters long (1,092 ft) and 78 meters wide (260 ft), and its displacement is 100,000 long tons which is equal to 224,000,000 pounds and 101,600,000 kg.  It is powered by two nuclear power reactors that provide 190 megawatts.

Now for science!

There was a shot in the movie when two of their fans were shut down and the ship was plummeting.  The altimeter read between 17 and 18,000 ft.  So I will begin by assuming they were cursing at 30,000 ft.  This is also where many commercial flights travel.  I will also assume that it takes about 30 minutes to reach cruising altitude.
CREDIT: Marvel Studios
Now I can estimate the acceleration.  Kinematics, the study of motion, says that for a body initially at rest, the acceleration is given by

Plugging in gives a value of 0.006 m/s/s.  For you non-students of physics, this means that for every minute, the carrier goes almost 1 mph faster.

Now for Isaac Newton.  To produce this acceleration, Professor Newton says that unbalanced forces have to act on the carrier.  Newton's 2nd law:

Here I will have to use the ship's displacement as its mass.  The displacement measures how much water an object pushes out of the way.  Rather than trying to calculate the ship's mass, I'll take the shortcut.  The total unbalanced force is about 570,000 Newtons.

There will be two forces acting on the ship - the thrust and the gravitational force (commonly referred to as the weight).  The thrust has to be 570,000 Newtons larger than the weight.  We can find the weight by multiplying the mass by the gravitational field (9.8 N/kg).  Therefore the thrust is approximately 10,000,000,000 Newtons.

The total energy used in both speeding up the ship and raising it can be found by multiplying the thrust by the distance.  

Since power is the rate at which energy is converted, we can take the energy and divide by 30 minutes.  To raise SHIELD's ship requires 5,000,000,000 Watts; that's 5.0 gigawatts!  Earlier I noted that the 2 reactors aboard a US carrier provide 190 megawatts, SHIELD needs 52 nuclear reactors.

Now for those fans providing the thrust.  To try to calculate the thrust of a ducted fan, one needs an extensive knowledge of fluid dynamics and aeronautical engineering plus a powerful computer.  I'll take the quick path to the answer.

With a 0.16 second Google search of "thrust fan specifications", the first result was for Ventry Solutions, Inc.  They sell a 24 inch ventilation fan that supplies 108 Newtons of thrust.  I'll scale that up for the ducted fans seen in the movie.  

Judging from the photo above, the fans have a diameter of about 40 meters (130 ft).  If - a very big if - the thrust is proportional to the diameter, then one fan can give 7100 Newtons.  Uh oh.  7100 Newtons per fan; 10,000,000,000 Newtons needed.  

14 million of them.

Sunday, May 27, 2012

Good Bye University

This is a YouTube video of a student, ABillyRock, saying goodbye to the University of Utah.  I don't understand her.  She complains that the university "bills itself to be a world-class university," yet she has presumably spent the last four years there.  She derides her Theatre department as "third world class."  She spent four years there despite it being "waste of my time and a waste of my money."  She whines, "I'm so sick of paying for it."

Here's how I see it.  ABillyRock may have wasted her money, but she wasted mine, too.  The University of Utah uses both state and federal taxes to subsidize her education.  She seems that she didn't take advantage of opportunities afforded her nor did she appreciate them. 

I really don't get people of this ilk.  They complain about the American education system all the while being a part of it.  ABillyRock had other choices.  There are plenty of private institutions - why didn't she choose NYU, Northwestern, Stanford, USC, Tufts, or Yale.  All highly rated theatre departments.  Later in the video, she reveals her politics.  Once she did, I wondered why she didn't attend a for-profit institution such as the University of Phoenix.  [For the record, Phoenix don't offer a theatre degree.]

Courtesy of the University of Utah
She goes on to "commiserate with any of you who have ever gone to or are currently attending public university."

"Public education from primary all the way through university - for the most part, in my opinion - is complete bullshit."

"It is a factory turns out statists by the millions."

Did you see/hear that?  Statists.  Simply put, a statist is a believer in a government that has substantial centralized control like a federal style government.  Like the United States of America.

The only people I have ever heard use the term statist are right-wingers.  If I remember my US history courses correctly, we tried a non-federal system.  Remember learning about the Articles of Confederation and Perpetual Union?  It states "Each state retains its sovereignty, freedom, and independence, and every power, jurisdiction, and right, which is not by this Confederation expressly delegated." The US's first government was so weak, the founders knew they had to replace it with a much stronger, more centralized, federal one.  I would ask her if she would prefer going back to the confederation, but her history courses were probably a waste of her time, too.

Then we get her philosophy of education.  "I favor how we used to learn trade.  Apprenticeships, that sort of thing.  How you actually learn a trade.  Not sitting in a class hearing about how Karl Marx is Jesus."

She means neither apprenticeships nor trades.  Usually a trade refers to a job requiring expert manual skills.  Examples of trades include electrician, plumbing, and carpentry.  In many trades, aspects of the apprentice program has been replaced by on-the-job training and vocational programs at community colleges or for-profit institutions like DeVry.  Theatre has never been considered a trade; it is an art.

She may be referring to mentoring.  The mentor relationship, an experienced person counseling and training someone new, is important in academia, the arts, and business.   Unfortunately, ABillyRock probably never tried to develop a relationship with one of her professors and so deprived herself of the very thing she desired, a mentor.

"Karl Marx is Jesus." I'll give her the benefit of the doubt here.  I assume somewhere, sometime in her 16 years of public education a teacher explained hyperbole. 

Thursday, May 24, 2012

Student Barometers

I'm not writing about pieces of lab equipment; rather about "something that reflects changes in circumstances or opinions."  So what's a student barometer?

Do you have them? They don’t show up every semester, so consider yourself fortunate if you get one, and powerball-level lucky to get two or more in a class. These are the students whose faces are an honest reflection of how well you have explained something. If you are less than clear, an eyebrow might go up, or a head might tilt just a bit. Another student might be nodding in agreement, but frankly, always nods in agreement, even if you are presenting the old, wrong, out-of-date view you are about to demolish. 
But the barometer student is skeptical. Listens. Processes. Understands. And (most helpful to you) it’s written on her or his face. Just spoke with one of three such students this semester (lucky me!), who I would have sworn was lukewarm about this class. I could not have been more wrong (I blame cultural differences; this student was from overseas). Once again, I am a happy Cuttlefish. And a sad Cuttlefish, because this particular barometer (indeed, two out of three of this semester’s barometers) is graduating, and the odds are we will never meet again. 
I suppose by this time in my career I should be accustomed to never seeing people again after becoming invested in their lives. Maybe I am, and the sadness is not strange, but simply an appropriate reaction to the situation. “Accustomed” does not mean “immune”.

Sunday, May 20, 2012

Gorgeous Shot of Today's Eclipse

This photo was taken by Sara Chuaycharoensuk, a student of mine, and it's my favorite of the ones I've seen today.  What you are seeing are images of the eclipse formed by pinhole cameras.  Where are the pinholes, you may be asking.  The spaces between the leaves of a nearby tree!


Thank you Sara for the photo.

Sunday, May 6, 2012

Wine Prevents Aging?

"Resveratrol: Study Resolves Controversy On Life-Extending Red Wine Ingredient, Restores Hope for Anti-Aging Pill
A study in the May issue of the Cell Press journal Cell Metabolism appears to offer vindication for an approach to anti-aging drugs that has been at the center of heated scientific debate in recent years. The new findings show for the first time that the metabolic benefits of the red wine ingredient known as resveratrol evaporate in mice that lack the famed longevity gene SIRT1."

I think this calls for a really nice Oregon Pinot Noir.

Teens These Days

Have you seen the news reports about teens playing the "Salt & Ice" game?  It involves sprinkling table salt on your skin, and then putting an ice cube on top of the salt.  You then are supposed to press down on the cube until the pain is too much to bear.

What's scary about this is that serious tissue damage can result.  Frostbite is a real possibility.  With frostbite, "ice crystals form in the space outside of the cells. Water is lost from the cell's interior, and dehydration promotes the destruction of the cell."*

Furthermore, "as blood flow returns to the extremities upon rewarming, it finds that the blood vessels themselves are injured, also by the cold. Holes appear in vessel walls and blood leaks out into the tissues. Flow is impeded and turbulent and small clots form in the smallest vessels of the extremities. Because of these blood flow problems, complicated interactions occur, and inflammation causes further tissue damage. This injury is the primary determinant of the amount of tissue damage that occurs in the end."*

Now that I've dealt with the biology, let's discuss the physics.

You learn in your science class that water freezes at 32ºF (0ºC).  Now that's really only true for pure water.  Dissolving any substance (salt, sugar, alcohol, antifreeze) in water will lower the temperature at which the solution freezes.  A solution that is 23.3% salt by weight will freeze at -6ºF (-21ºC).

Here's what happens in the "Salt & Ice" challenge.  The ice cube coming from a typical freezer may be at a temperature of 0ºF (-18ºC).  Since it's in contact with your skin, some ice melts.  The water that results is at 32ºF (0ºC), but it mixes with the salt.  Since the salt-water is in contact with the ice cube, the water cools down to the temperature of the cube.  

Let me repeat that last point.  The salt-water is at a temperature as low as 0ºF (-18ºC).  

It's the cold water that poses the danger here.  It takes a relatively large amount of energy to change water's temperature.  Scientist call this thermal property the specific heat.  So energy is being transferred from your skin to the salt-water, your skin cools drastically, and the salt water barely changes temperature.  In fact, the salt-water really doesn't change temperature at all, since it's still in contact with the ice cube.

We can use this physics we have have friends over for grilled meat.  If you happen to forget to cool off the beer, add the drinks and ice to the cooler.  Then pour in some water and some salt.  You'll have cold beer in no time.  The only way to get it colder and faster is with liquid nitrogen, but that can be a little hard to come by.


Saturday, May 5, 2012

Keep Your Hands Inside The Ride at All Times

Not just a good idea; it's the law!
The Large Hadron Collider at the European Organization for Nuclear Reseach (CERN) uses a beam of protons to investigate the most basic nature of the universe.  It does this by accelerating the protons to a speed of 0.999999991c; that is 99.9999991% of the speed of light.
Courtesy of CERN

So the people at Sixty Symbols [I highly encourage visits to this site!] asked scientists what would happen if one were to stick a hand into the proton beam.

Here's the video: