Physics: July 2005 Archives

I suck at classes in which you have to memorize a lot. This seems to be a function more of temperament than ability, as I often show signs of an almost perfect memory. It's not that I can't memorize, it's that I hate doing it. I want to see a pattern, connections between otherwise trivial data and equations. You could say my avatar hates memorization and rotes. (But only if you were a major nerd like I am.) So I have a really good memory, but I very rarely ever put it to conscious use. More often than not, my memory manifests with the untimely revelation of crap you did not want to know at exactly the wrong time. (The example that popped into my head was discussing variations in bat guano at a wedding, which is weird, because I've never done that. I suppose I don't go to very many weddings. And I don't really know much about bat guano.) This probably doesn't sound like much of a curse to you, but what you don't realize is the practical implication of this with regards to academia. That is, I have this awful tendency to recall idiot mistakes I made on tests immediately after handing them in. Today's promising specimen, realized while congratulating self on feeling good about this test in spite of missing one of the lectures:

Air in a cylinder at 15°C and 1 atm is adiabatically compressed to one tenth its original volume. What is the final temperature and pressure, given that the air is perfect and gamma = 1.4?

Not too hard. To get the temperature, I used this equation and process (the y-lookin' think, for non-math/science geeks, is gamma): Overjoyed at finding how nicely the stuff I didn't know cancelled out, I moved on to pressure: I'm sure someone's already seen the mistake I made - I used the same exponent from the temperature equation, when this one should have been one bigger, like this: So much for 100%. Of course, it's just an order of magnitude off - it's not like I got the number and the magnitude wrong. Maybe he'll only take off a point or two.