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<p>I know I’m an engineer and that the way I look at things in the privacy of my own head may make liberal arts majors want to scream “NERD!” but when I would walk across campus I would often analyze the shortest distance between the library and the civil engineering building. They had diagonal walkways that cut straight through everything, but when there were hills, the walkways would follow the contour of the hill… made it a little more complicated than what a third-grader could do.</p>
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<p>This is kind of the difference between the engineering-trained mind and the non-engineering trained mind. The way I look at it is far nerdier. I could sit there and time how long it took for things to overflow in my garden tub in my apartment, or I could estimate the curve of the tub, estimate the flow of the faucet, and do a quick bit of calculus to figure out how long I can walk away for, at least, until the tub overflows. (YES, I <em>know</em> it’s insanely geeky, that’s why I don’t tell people that I’m doing it. Still, I can walk away from the tub for a good eight minutes while you’re checking back on your tub’s progress every couple of minutes.)</p>
<p>I also kick butt at those “guess how many M&Ms are in the curved glass jar” things. The only variable is knowing what the approximate density of loose-packed M&Ms is. (This is why I typically do these things in the privacy of my own head.)</p>
<p>I have a fun car. Quick, sporty. It’s fun to accelerate into curves, but I’ve had some speeding tickets, so I start off ~10mph slower and accelerate so that I hit the curves at a max of 5 mph above the speed limit. I don’t actually do calculus on this (because you shouldn’t do calculus when you’re driving) but since I have enough familiarity with how those curves look, I know I should hit 60 mph <em>here</em>, then 65 about <em>here</em>, and that should put me at 70 mph <em>here</em>, at the outer arc of the curve.</p>
<p>I have this really curved coffee cup provided by my company, and I’m kind of a snoot about my coffee, so I have a french press, and it measures things in milliliters. I’m mildly embarassed to admit that I approximated the curve of the coffee cup and integrated from the lower radius in centimeters to the upper radius in centimeters to figure out about how many milliliters of coffee I needed to make in order to not have my cup overflow when I poured the coffee into my cup from my french press. See?? Seeee why I didn’t give examples?? =P </p>
<p>It’s one of those things that can be used everywhere, but you don’t ever really want to say what you use them for, because it’s just ridiculously overkill… but it makes it just a little bit easier. Pour coffee like a pro? Maybe you’re awesome at coffee. Maybe you just do calculus in your head like the lame dweeb that you are.</p>
<p>It’s like this tool where once you’re adept at using it, you start seeing integrals and derivatives in everything, and you habitually bring out the shotgun.</p>
<p>Now, I do use this in my everyday life, as an engineer. I have to calculate the centroids of weird shapes pretty much all the time, to calculate the moments of inertia of various shapes to understand how they’ll behave when I make them out of steel and hang them on a building. So while you guys may think that it’s like using a shotgun to kill a fly, in my mind, I already know how to use the shotgun pretty well and I’m sure as heck going to nail the fly if I use it. Also, if I solve things using more than one method of calculation (I do a lot of these things using geometry <em>and</em> calculus) then I’ll end up with more confidence in my answer.</p>
<p>I just don’t tell anybody I’m doing it. If I use calculus to make my morning coffee, I know full well that it makes me a freak.</p>
<p>Still, all these mental jumping jacks are why I can look at a numerical situation and figure it out very quickly. That’s what engineering and thinking-in-calculus have trained my brain to be able to do, and it’s the very thing that my job requires. “If the computer has calculated this correctly, this should be at about <em>this</em> number… and it is; good… and this should be about <em>here</em>… Okay, excellent, this is correct.”</p>
<p>Now, I don’t make fun of <em>you</em> for <em>not</em> using calculus. Please don’t make fun of <em>me</em> for using calculus. It’s not like I’m getting out my slide rule when I do this stuff, it’s just that I’ve done it enough and I know what enough curves look like that I can approximate these things pretty quickly and with little effort… I just do it all the time, so it’s a useful solution for me. Don’t go out and learn calculus just for the mundane little details of your life, though, that’d be pretty unnecessary. You buy a miter saw if you’re going to install crown molding, you learn calculus if you’re going to be using it fairly often. Common sense and a little extra time can easily take the place of most of the things I use calculus for. Still… if you’ve got it at your disposal, it’s pretty handy.</p>