Home > Success and Failure > Does This Roller Coaster Have a Loop-the-Loop?

Does This Roller Coaster Have a Loop-the-Loop?

‘Cause it’s certainly got its share of up-and-down bits.

Last time I posted I was moaning about my brain having seized up after a maternal MINI malfunction cost me most of a day’s working time on my ECE 101 homework.  I ended up turning that homework in with two out of the six problems omitted altogether and one only one-quarter done, with a rather pathetic little note attached explaining that I couldn’t see how the other three sub-questions differed from the first one.  That happened on Friday morning.

On Saturday, my father had to go into work for a while, and when he was done he swung by my house.  I repeated the moan about my homework, grumbling that I’m really not sure this electrical stuff is working for me, and he asked if I could show him what had gone wrong with that question.  So I did.  I’ll spare you the details, but it had to do with working out the relationship between various resistors in a fairly complicated resistive circuit, and changing the two reference points between which you’re evaluating same.  Doing that changes the relationships within the circuit, and though I knew that, I could not for the life of me see how.

Dad looked at it for a couple of seconds, then said, “Well.. what if you thought of it this way?”

What I ended up doing was envisioning the components in the circuit as, basically, “Doctor Nesbitt’s Electrickal Machinerie” – electronic hardware at its most cartoonish faux-Victorian absurd scale.  Resistors the size of fists attached to enormous brass bus bars by cables as fat as your thumb, insulated with the finest gutta-percha from the east end of the Empire.  And then it suddenly made sense.  Imagining the two reference points as physical bars of metal with cables clamped to them made it all fall together for me.  (Those of you who’ve been to WPI may find yourselves picturing that streetcar equipment that is, or used to be, in the lobby of Atwater Kent Labs.  That’s pretty much what I had in mind.)

Fired up by this epiphany, I spent a decent chunk of the afternoon finishing up the missing bits of last week’s homework and then, just for good measure, did this week’s.  It’s not due until Friday, but damn me if it’s not already finished.

This afternoon, figuring that I wouldn’t get any credit for it – which is fair, since I didn’t turn it in on time – I took my weekend’s work over to Andy’s office, just because I wanted to see whether I had in fact gotten it right.  He looked it over, pronounced it satisfactory (I’d done a bit of the math in question 4 wrong, but the theory was correct, and the aforementioned analysis was spot on), and, to my considerable surprise, gave me a fairly substantial percentage of base credit for it.  He liked that I hadn’t just given up after blowing the deadline (and a mental radiator hose) on Friday.  He also liked the mental-bus-bars trick, though he warned me that later on, there will be circuits that I won’t be able to do that for.

I admitted that I’m still pretty lost as to what we’ve covered over the past couple of lecture days, and he agreed that it’s liable to be pretty baffling to someone without a calculus background – but calc isn’t actually a prereq for the course, so we’ll see what happens.  We haven’t actually reached the point where we’ve got homework on RC circuits to do.  It may become clearer once there are examples to dig into.  Or not.  But we’ll burn that bridge when we get to it.  In the meantime, since we haven’t had homework on it yet, they won’t be on Friday’s exam.  Which is good.  Did I mention we have an exam in that class on Friday?

No word yet on how bad I screwed last Wednesday’s MAT 122 exam in the ear.  I’m not expecting good things.  Still, I’m willing to accept the weekend’s turnaround on ECE 101 homework #6 as a victory snatched from the jaws of defeat.  All thanks to my father prompting me to, in essence, look at an electrical engineering problem like a mechanical engineer.  That gives me something to think about vis-à-vis my choice of discipline.  That and the continuing preponderance of computer-related stuff cropping up in my ECE 100 seminar.

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