Airplanes That Seem to Hover

Last year I posted an article about the fundamental principles behind how a subsonic aircraft works.  In summary, an airplane takes off once a critical speed is reached: the greater the speed of the wings relative to the air being cut by them, the greater the pressure difference between the air on the top and bottom of the wings, and the greater the lift force.

Now, I would like to address a particular concern about airplanes that some of my students have had.  Have you ever looked up at an airplane, and had the impression that it was barely moving?

Helicopters, hot air balloons, and some supersonic aircrafts possess the ability to hover, but subsonic aircrafts do not.  As already mentioned, the only reason that a commercial plane can maintain a given altitude is because it is moving horizontally with respect to the air around it.

So, what is going on here?  I too have looked up at aircrafts as they descend and have remarked, on occasion, that the plane seems to be moving at a snail's pace.  Sometimes an airplane flies above me as I cruise along the highway, and my impression is that I am in fact moving faster than it relative to the ground.  Is it an optical illusion?  Let us investigate.

The Wondrous Night Sky

When my daughter recites twinkle, twinkle, little star, I am tempted to answer her question regarding what they are: "Giant collections of particles moving in all directions colliding into one another at high speeds forming larger particles in fusion reactions that give off heat and light..."  And then I remember that she turns three this summer.

I got to thinking about stars when a couple of callers rang me up the other day on my call-in show.  OK, I don't have a call-in show.  It was just a couple of friends calling me at home with questions about stars.  They were either genuinely curious about these glowing masses or were poking fun at my passion for all things science.  I am going to assume it was genuine curiosity, and answer their questions below.

Pushing the Boundaries of Science Like Pushing a Vacuum

As far as division of labour around the house goes, my wife and I each have our own respective duties, and one of mine is vacuuming the house.  I kind of enjoy mindless activities like this one, because it allows me to shut off my brain for the better part of thirty minutes.  But with the mind unfocused, it is at once free to wander; I find that I do some of my deepest thinking while under the hypnotic trance of the vacuum's purr.

Once, while seeking out lose dirt and dust-bunnies with my trusty dust-sucker, my mind began to wander even further than normal.  I began to see clear parallels between my search for dust around the house and humanity's pursuit of science in general.  Before I go any further, let me assure you that I realize that only one of these two endeavours is of great importance, and it is not the one that involves me pulling out the couch, cleaning behind it, and pushing it back.

Dust around the house tends to accumulate in the places we encounter the least.  Sections of the home in plain sight are relatively free of such particles, as these areas are well-travelled.  The dust gets displaced to a new spot due to the relative motion of air around it.  If this new spot also sees regular activity, the dust will inevitably move yet again.  It will only settle permanently in a quiet, unused spot within the room (usually behind something heavy, to the vacuumer's chagrin).  The phenomenon is much like snow on a high-traffic ski slope, which tends to build up on the two outer edges.

How then is vacuuming like scientific advancement?  Imagine that each piece of dust to be collected is like a scientific mystery to be solved.  Much like the loose dirt that we wish to suck up, the vast majority of the mysteries associated with the physical world are well-hidden - that is, unless we search for them explicitly, we will not even know that they exist.

Each room within the house may be thought of as a scientific pillar, each with its own particular sort of unsolved mysteries waiting to be uncovered.  We could have physics in the family room, chemistry in the kitchen, biology in the bathroom, and so on.

In the early going of modern science, the house was a complete mess throughout.  As almost no one was taking part in scientific research, dirt was evenly distributed.  When Isaac Newton decided to begin to clean the house, he began with what he interacted with most on a daily basis - that which was the most visible.  In the late seventeenth century, he uncovered the basic principles of mechanics (the motion of bodies) and geometric optics (the behaviour of visible light).

As the study of physics moved along, research in other fields of science began.  Before long, each room in the house was being cleaned in parallel.  The science research landscape was a busy one indeed during the twentieth century. 

As the dust settles, and the twenty-first century soldiers on, we may look at the house and conclude that it is clean.  Scientific principles may be invoked to explain just about everything we typically interact with.  That which was most obvious, that which presented itself, has been sucked up by the scientific research community.  All that remains to be discovered in the present science landscape is that which is not in plain sight.

Ender's Game, The Movie

You know that uncomfortable feeling that you get upon learning that your absolute favourite novel will be spun into a Hollywood film?  I am currently dealing with such a feeling in regard to my favourite sci-fi novel, Ender's Game, which will hit the big screens in the spring of 2013.  On the one hand, I am excited to experience this wonderful story through a new medium, but on the other, I fear that the movie will not live up to the book. 

It is strange for one to have such strong feelings for a story that one takes offense to a lacklustre portrayal of it.  After all, I am not Orson Scott Card, the author of the Ender's Game series of novels, of which Ender's Game was the original publication.  But, that is what is special about a novel: the reader has the freedom to make the story their own, and in so doing, develops a much more intimate relationship with it than can be established through film.

I first read Ender's Game (I have read it twice since) in 1999, as part of a college English class.  The 1985 novel may be summarized as follows: Star Wars meets Harry Potter without the hocus pocus.  The story examines two advanced species, mankind and formics (commonly referred to as "buggers"), for whom this neighbourhood of the universe is not big enough.  The story unfolds almost entirely on a military base in space, where young boys and girls are trained in space war.  Harry Potter fans will draw comparisons between this training facility, known as Battle School, and Hogwarts, but to be fair, J. K. Rowling's fictional world was created after Card's.

The Art of Presenting

As part of my physics courses, my students are usually required to perform a powerpoint presentation about a course-related topic that they find interesting.  As harmless as it sounds, the very idea of speaking in public induces fear in many of my students.  While I do sympathize with them, these presentations remain a part of my courses because (1) oral communication is an important skill, and (2) I feel that if you cannot communicate what you have learned, you have not learned it.

Jerry Seinfeld once observed that the number one fear of most people is public speaking, while number two is death.  He went on to muse that, at a funeral, the majority of people would rather be inside the casket than giving the eulogy. 

What is it about giving a presentation that is so scary?

Engineering Firms Can be a Drag

I had the great privilege of taking in a 45 minute long keynote speech by Canadian astronaut, Dr. Robert Thirsk, at a teacher's workshop last month.  The speech was about inspiring students to pursue the sciences, and also included an inside look at the incredible career that Dr. Thirsk has enjoyed.  To be clear, the overall message was not "Inspire young students in science and math and they will all become astronauts."  While the presentation did include awe-inspiring visuals of Dr. Thirsk floating in low Earth orbit, the take home message was grounded in reality: science is interesting and can lead to a wide spectrum of promising careers.

But, let's be honest.  No engineering career stacks up against what Dr. Thirsk and his handful of colleagues do. Not more than two years ago, the man at the microphone took part in forty unique science experiments over a six month period aboard the International Space Station.  He ate space food and exercised on specialized zero-g cardiovascular machines for two hours per day (to minimize bone density loss).  For every engineer that can boast about a work experience as rich as this, there are literally thousands who spend their days deciding whether to use three bolts or four bolts to connect parts at interfacing flanges.

What, in the first place, draws engineers to pursue a career in engineering?  Usually, possessing strong math skills and having a comfortable understanding of physics can sway a young student towards the direction of engineering.  However, the desire to work on ground-breaking projects - the first lunar mission, the first nuclear reactor - this is what budding engineers envision for themselves.  Engineers want to have a hand in shaping the technological landscape of the future.  The sad reality is that only so many hands have the opportunity to take part in such shaping.

You Cannot Eat Money

When all the trees have been cut down,

when all the animals have been hunted,

when all the waters are polluted,

 when all the air is unsafe to breathe,

 only then will you discover you cannot eat money.

- Cree Prophecy

The economy is based on an imaginary entity; it is a currency called money.  While it makes sense to have a currency whereby goods and services can be easily exchanged, this modern method of trade allows us to forget that money, in and of itself, is worthless.  The quotation above illustrates this notion with absolute clarity.

Modern society is so far removed from a time when one's needs to survive and prosper were met through direct action (the collection of one's own food and shelter).  To be clear, I have no desire to turn back the technological clock to a time when societies did not enjoy the benefits of divided labour.  But it is helpful to consider the hunter gatherer way of life, if only to allow us to correctly identify what matters.

Going on a camping trip is a great way to briefly escape the economic landscape, and to accurately reflect on what we truly value.  I actually tried ice fishing for the first time this past weekend, and in my group of four, we caught three small fish collectively over the course of many hours.  Without modern agriculture, and environmental conditions in which it can thrive, we would all be screwed.

Vanier College Robotics Club Gives me Hope

I tend to keep the college at which I teach and this blog on which I write as separate entities, as there is no actual affiliation between the two.  But I am a mentor for the Vanier Robotics Club "Build Team", and today, I really want to praise them and the entire Vanier Robotics Club for their accomplishments over the past four months.  I urge adults who fear that today's youth have become lethargic to read on.

Vanier College hosted Profuga 2012, the 11th edition of the CRC Robotics competition, inside its Sports Complex over the past three days (Thursday, Feb 16 to Saturday, Feb 18).  The annual provincial competition is run by a company called CRC Robotics.  On their website, they describe themselves and the competition as follows:

"CRC Robotics is a non-profit organization offering high-school and CÉGEP students a quality multidisciplinary competition in an entertaining, high-intensity environment to counter school dropout rates by inspiring tomorrow's leaders. Students are challenged to build a robot and to produce a video, web site, and kiosk presentation, where all tasks are entirely student-run."

This year's robotics challenge was ultimately a series of two-on-two capture the flag heats, where schools alternate who they compete against as well as alongside.  The terrain on which the robots did battle had ramped surfaces.  Designing a robot that can not only manipulate objects, but do so while translating up or down a 20 degree incline is no easy task.  However, the tech-savvy students composing the Vanier Build Team and those of tens of other schools were up to it.

It may surprise you to learn that the goal in this competition was not to chop other robots to bits with buzz saws or axes (I must admit that this was the particular image I used to associate with robotics competitions). But there are a couple of reasons why, in my view, a relay-race or capture the flag is a much better choice than a battle to the death for this particular competition:

(1) The event is longer when robots don't get sawed in half.
(2) Canada in general (and the province of Quebec in particular) has a fairly pacifist mindset.  

"Speed", Featuring Keanu Reeves and Mechanics

The 1994 action thriller Speed introduced America to two soon-to-be movie stars in Keanu Reeves and Sandra Bullock.  The film contained all of the escapist elements that a summer outing to the theatre is supposed to: adrenalin-fuelled intimacy between the two leads, a smart yet mentally deranged villain, and lots of things that can and eventually do go boom. 

Yet, after the credits role, and the movie goers make their way home, the images that stick with them are not those of kissing, lunacy, or explosions, but rather the exciting set-pieces involving mechanics that are continuously on display.  From the elevator on which the film opens, to the bus, where the majority of it takes place, to the subway on which it concludes, it feels like a 116-minute mechanics course, albeit an entertaining one.  I don't know this for a fact, but I would suspect that director Jan de Bont took a physics class as a kid and enjoyed it immensely.

I suppose it is not surprising that the movie features mechanics, as its title is a key term of kinematics - speed is defined as the magnitude of velocity.  And, when an ex-cop turned psycho attaches a bomb to a city bus, he programs it with this kinematic parameter in mind: the bomb is armed once the bus surpasses a speed of 50 mph, and is set to blow should it ever fall below this value again.

If there were more class time in the Mechanics course that I teach, I would actually show Speed in class.  And, after each action sequence, I would pause the film to discuss the key concepts of mechanics on display, and even solve explicitly for some of the unknown parameters.  As this exercise is quite time-consuming, I simply encourage my students to try this activity on their own.

In the first scene alone, many aspects of mechanics are highlighted when an elevator filled with innocent people threatens to plummet to the ground.  The periods of free fall experienced by both the elevator and those inside begs several questions, like "Should the passengers float upwards?" and "Would they increase their likelihood of survival if they jumped just before the cabin hits the ground?"  I'll leave readers to consider these on their own.

When the cabin and its contents are supported by a single rope, how much tension manifests inside it?  Does the rope extend, and if so, by how much?  Why does the supporting crane above break?  I'll answer this last one: the tension in the cord creates a large moment (or torque) about the support structure.  The bending moment leads to a local stress that is larger than the ultimate stress value of the material making up the structure.

We could go on and dissect the mechanics of the entire film in this fashion, but instead, I would like to focus on two particular action sequences in some detail.  These two sequences occur on the fast-moving bus, and I always discuss them with my mechanics classes.

Guinness Book of World Records a Useful Resource

One of the first books I ever bought, The Guinness Book of World Records - 1992 edition, is still, in my mind, the most informative and entertaining among those that sit on my book shelves.  Where else can one turn to when they want to know the height of the tallest person (8' 11", Robert Waldo), the maximum combined length of finger nails on one hand (181 inches, Shridhar Chillal), and the maximum g-force experienced by any bird (10g's, when the red-headed woodpecker strikes a tree)?

Well, I suppose one could turn to Google, but performing such searches would be much more arduous.  Also, no one would even think to search for most of the endeavours described in the Guinness Book.  In fact, much of the fun in flipping through this record book is had by marveling at some of the most bizarre records it contains, such as the longest leapfrogged distance (888.1 miles by 14 members of a high school class during a 189-hour and 49-minute span).   

From business to the arts, science to sports, anything that has a maximum or minimum is likely captured within those 833 pages.  And, I would go so far as to say that The Guinness Book of World Records is a vital tool for all engineers.  Let me explain...