Dimensional Analysis as a math technique: is this ever, ever useful?

anyone?

It's useful to me in my work, for preliminary system feasibility models and to simplify some of the code I write. I can't say I rely on it for any day-to-day life stuff though.

Yeah, I'm not thinking day-to-day but for future science applications and most of all for future science classes.

You may run into problems in which the particular unit conversion in question is more involved than what you're used to, but once you've gotten the hang of it, it never gets conceptually harder, just more involved.

It's useful for pretty much any multivariate system, so yeah stoichiometry, thermodynamics, statics/dynamics, stress analysis. And anything having story problems.

Wow! Euler answered my question!

At this point it's just all these ones that cancel out in the numerator or denominator, and it's easier for me to set it up as a simpler ratio right now. Will this always be the case?

No, they're just making you take baby steps with it to start with.

I H8 BABY STEPS

even tho they are useful

says the person who writes out every teeny tiny step of her math problems

Dimensional analysis was useful every time I could only half-remember a formula in an exam, but that's not really a practical use. In the real world you look the formula up. But it totally saved my ass this afternoon. I was about to spend a week or so coding up some unit conversion stuff, which is error-prone and tedious.

I've found it can be pretty useful at certain times. I just hate having so many items where the numerator, denominator, or (especially) both is "1."

:( I forget this

At this point it's just all these ones that cancel out in the numerator or denominator, and it's easier for me to set it up as a simpler ratio right now. Will this always be the case?

-- Abbott

what does this mean? could you give an example?

I'll TRY, not sure if the formatting will come out right:

24.3 g  KCl * 1 mole KCl * 6.022x10^23 KCl atoms 

              ----------   --------------------- = 1.96x10^23 KCl atoms

              74.6 g KCl        1 mole KCl

when it COULD just be set up like:

24.3 (6.022x10^23)

-----------------

     74.6)

like I know that at the top is Avogadro's # and at the bottom is weigtht of KCl, I know those both mean MOLE, so why throw in "1 mole KCl" twice just so I can cross it out?

It's easy to invert a conversion and not realize it. So you trade more writing at every step for a guarantee that you didn't screw up. You can save a bit of writing/crossing out when you're doing these long string-of-fractions-multiplied-together conversions by just writing the common units (ex. 1 mole KCL) diagonally between where you're writing them now. That's what I used to do, but I'm a huge nerd for notation.

OK thanks abbott!

i did it once, for real, it is good for figuring out how somebody fucked up something that you can't figure out how is fucked up