Onto PHYS 2010!!
The Professor was very intimidating the first day. Professor Kumarakrishnan (Kumar for short) turned out to be one of our favorite lecturers. Although it was very clear to us that he was no normal human being. We're pretty sure the man didn't need sleep. In fact, after one very typical lecture he asked us how we thought the quality of the lecture had been. We told him it was on par with his usual delivery and he was relieved. He told us that he had not slept for over 72 hours and was worried that it might affect his teaching!
I have Professor Kumar again this semester (or I did. I finished exams 4 hours ago) and his class is one of my favorites. Don't worry. I will definitely do a post about his laser lab course.
Another name for "classical mechanics" is "analytical mechanics" and that is the name of the course textbook.
The beginning of the course focused on some simple motion and forces. These topics are covered in first year, but now we've been equipped with some better math and can approach them differently. For example, in first year we were taught that the famous equation of Newton's 2nd Law of Motion is
F = ma
Force = Mass x Acceleration
While this is true, it is only part of the picture. We learned that this is something called a "differential equation" and that there are general and particular solutions to it, and that we need to figure out what they are.
The main focus of this course was something called The Harmonic Oscillator. Now, I was not aware at the time how fundamental this is to upper-level physics. Kumar told us that almost anything can be modeled by the Harmonic Oscillator. While we of course believed him, we did not know just how true his claim was.
The model we use is simply a mass on a spring in different configurations. Sometimes there is an outside force periodically driving the motion of the mass like a kid being pushed on a swing (The Driven Harmonic Oscillator). Sometimes there is some type of drag or friction slowing its motion like a guitar string (The Damped Harmonic Oscillator). And of course we did both (actually the kid on the swing is both since the friction of the chain at the top and air drag on his body both slow him down) (The Damped Driven Harmonic Oscillator). Now, damping can take on three classes. One is underdamped: it reduces the system's energy very slowly. Another is overdamped, which reduces the system's energy very quickly. Then there's critically damped, which is tuned to damp a particular system in just the right way to kill the oscillations as fast as possible. The shocks in your vehicle are critically damped. Otherwise you would bounce for several seconds after every bump. The ugliest equation (by far) of each of these is that of the underdamped H.O. I found it online at www.hyperphysics.com. While the one we used was a little different, it encompasses all the same things, and gives a very good idea as to how nasty this thing is.
Some of the shock and awe of the equation comes from all of the unfamiliar symbols. They're just Greek letters that after some practice you get used to. It's like using an extended alphabet to have more to work with (in fact, that's exactly what it is). I see a phi, an omega, a gamma, and variations (such as phi-sub-d in the top right corner). Other than that, you're familiar with the different things in there. Cosines and Sines, "t" is for time, "A" is just an undetermined coefficient (a number whose value we don't know yet), some square-roots. Before you become all impressed, understand that the blue highlighted equation is the one you work with. The other boxes help us know what the different parts mean, but we don't have to manipulate this whole nasty beast all at the same time. We work with it in small parts. I don't think I could have managed everything at once.
Well, about two thirds into the course Kumar got a big fat grant for some of his research and was pulled out of our class. We got another professor, named Terekidi. It quickly became clear that he was another brilliant mind, but this switch really messed with us. It was around the time that we were starting to run out of steam. It was when we had become accustomed to Kumar's style of marking and teaching. And it was right when we were transitioning into the topic of the "Motion of Rigid Bodies in Three Dimensions" (even harder than the H.O.) The combination of these things made finishing the class on a high note ten times more difficult, and I didn't. I landed right on the class average and came out disappointed.
One of my favorite moments of this class was when Kumar had set up a very long and tedious derivation and was taking us through it. He went through four to five chalk boards of equation after equation building up to something when suddenly things started to fall into place and out popped a very familiar form of Newton's 2nd Law. We were all so pleased and impressed we actually applauded when he finished his lecture and we all walked out talking about how awesome that was. One student said "it was like wandering in the woods and finding a road and suddenly recognizing the neighbourhood and knowing how to get home" which I thought was a very good analogy.
Thanks for reading! My next post will be about another class. Maybe a third year class. Cheers!
Totally Awesome!! A capable engineering professor once told me that you only need to know 2 things to be a good mechanical engineer: (1) F = ma and (2) "You cannot push on a rope".
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