# What is your favorite equation? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 21, 2006, 1:48pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280 "2006-11-21T13:48:49Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![xbuckeye](https://avatars.discourse-cdn.com/v4/letter/x/9e8a1a/32.png) [@xbuckeye](https://boards.straightdope.com/u/xbuckeye)\ **Post date:** [November 21, 2006, 8:26pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/21 "2006-11-21T20:26:22Z")
[QUOTE=Squink] Still, it’s hard to beat the tiny rhyme of PV = nRT. It simply _rolls_ off the tongue. [/QUOTE] You beat me to my favorite. We called it the pervert equation because once you’ve been studying long enough for you brain to start nodding off, it sort of looks like the word pervert in some fonts. ---
**Author:** ![the\_chicken\_of\_exeter](https://avatars.discourse-cdn.com/v4/letter/t/ac8455/32.png) [@the\_chicken\_of\_exeter](https://boards.straightdope.com/u/the_chicken_of_exeter)\ **Post date:** [November 21, 2006, 8:27pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/22 "2006-11-21T20:27:26Z")
I like the equation of the normal distribution. Because it looks pretty. (not a mathematician) ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [November 21, 2006, 9:47pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/23 "2006-11-21T21:47:55Z")
A really simple one: d=rt I had a mental block about motion problems so when it finally made sense it was a great feeling. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [November 21, 2006, 10:54pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/24 "2006-11-21T22:54:08Z")
[QUOTE=gigi] A really simple one: d=rt I had a mental block about motion problems so when it finally made sense it was a great feeling. [/QUOTE] I learned a pretty cool trick when learning how to solve problems like this. If you arrange them in a triangle like this: D R T Then, if you cover up (solve for) D, you get R\*T. If you cover R, you get D/T, and if want to solve for T, you get D/R. Pretty neat, huh? ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [November 21, 2006, 11:02pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/25 "2006-11-21T23:02:53Z")
A lot of simple equations work that way. Ohm’s Law comes out as ```auto E I R ``` Where E=volts, I=amps and R=ohms ---
**Author:** ![KJ](https://avatars.discourse-cdn.com/v4/letter/k/b2d939/32.png) [@KJ](https://boards.straightdope.com/u/KJ)\ **Post date:** [November 22, 2006, 1:06am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/26 "2006-11-22T01:06:10Z")
[Z[sub]n[/sub] = Z[sub]n-1[/sub][sup]2[/sup] + C](http://en.wikipedia.org/wiki/Mandelbrot_set) ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [November 22, 2006, 1:59am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/27 "2006-11-22T01:59:42Z")
My _least_ favorite is the Schrodinger equation. I dropped third semester Physics because of those third order partial differentials, only to have it again in graduate school. But I digress. Heat loss. Q=UA delta T. Wonderfull way to explain to Mrs. Plant why she should close the damn door, and turn the thermostat up or down two degrees. 🙂 ---
**Author:** ![monica](https://avatars.discourse-cdn.com/v4/letter/m/a183cd/32.png) [@monica](https://boards.straightdope.com/u/monica)\ **Post date:** [November 22, 2006, 2:37am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/28 "2006-11-22T02:37:52Z")
I am neither a math nor a science person. However, I’m a fan of the quadratic equation. I had to memorize the damn thing in seventh grade, and I still remember it. ---
**Author:** ![Beware\_of\_Doug](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@Beware\_of\_Doug](https://boards.straightdope.com/u/Beware_of_Doug)\ **Post date:** [November 22, 2006, 2:58am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/29 "2006-11-22T02:58:51Z")
The squaw on the [hippopotamus](http://varatek.com/scott/math_jokes.html) is equal to the sons of the squaws on the other two hides. ---
**Author:** ![Schuyler](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Schuyler](https://boards.straightdope.com/u/Schuyler)\ **Post date:** [November 22, 2006, 3:07am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/30 "2006-11-22T03:07:21Z")
[QUOTE=GargoyleWB] I like **F=ma**. You could derive any physical equation or concept from that starting point. At least until that meddlesome Einstein came along… [/QUOTE] Our instructor used that equation to unify a graduate dynamics course - each topic became a detailed study of one term (F, m, a, and ‘=’). 🙂 On a related note, I’ve always been partial to Kane’s Equation: **_F[sub]r[/sub] + F[sub]r[/sub][sup]_[/sup] = 0**\* ---
**Author:** ![Thalion](https://avatars.discourse-cdn.com/v4/letter/t/f475e1/32.png) [@Thalion](https://boards.straightdope.com/u/Thalion)\ **Post date:** [November 22, 2006, 3:38am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/31 "2006-11-22T03:38:53Z")
Damn, I love this place!! Only on the SDMB can you have this thread and [a thread about the witches on _Charmed_](http://boards.straightdope.com/sdmb/showthread.php?t=396304) on the same day. ---
**Author:** ![Clothahump](https://avatars.discourse-cdn.com/v4/letter/c/51bf81/32.png) [@Clothahump](https://boards.straightdope.com/u/Clothahump)\ **Post date:** [November 22, 2006, 4:13am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/32 "2006-11-22T04:13:48Z")
[QUOTE=TwoTrouts] The angle of the dangle is proportional to the heat of the meat. 😛 [/QUOTE] Actually, the angle of the dangle times the heat of the meat equals the square of the hair plus the cube of the tube. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [November 22, 2006, 4:18am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/33 "2006-11-22T04:18:27Z")
I like pi\*r^2 Cuz it’s funny. Like, you know…pie aren’t square, pie are round. _giggle_ ---
**Author:** ![Clothahump](https://avatars.discourse-cdn.com/v4/letter/c/51bf81/32.png) [@Clothahump](https://boards.straightdope.com/u/Clothahump)\ **Post date:** [November 22, 2006, 4:20am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/34 "2006-11-22T04:20:15Z")
And I like Boyle’s Law: (V1P1)/T1 = (V2P2)/T2 ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [November 22, 2006, 4:32am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/35 "2006-11-22T04:32:41Z")
i[sup]2[/sup] = j[sup]2[/sup] = k[sup]2[/sup] = ijk = -1. That and 2 + 2 = 2\*2. ---
**Author:** ![Larry\_Griffin-Kentzel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/larry_griffin-kentzel/32/14787_2.png) [@Larry\_Griffin-Kentzel](https://boards.straightdope.com/u/Larry_Griffin-Kentzel)\ **Post date:** [November 22, 2006, 4:40am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/36 "2006-11-22T04:40:10Z")
“What’s your favorite …?” threads belong in **IMHO**. I’ll move this for you. **Cajun Man** for the SDMB ---
**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\ **Post date:** [November 22, 2006, 5:21am UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/37 "2006-11-22T05:21:20Z")
After all of my actuarial exams I became rather fond of the annuity equation: a[sub]n[/sub]=(1-v[sup]n[/sup])/i ---
**Author:** ![SpectBrain](https://avatars.discourse-cdn.com/v4/letter/s/a87d85/32.png) [@SpectBrain](https://boards.straightdope.com/u/SpectBrain)\ **Post date:** [November 22, 2006, 9:31pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/38 "2006-11-22T21:31:23Z")
[QUOTE=Clothahump] Actually, the angle of the dangle times the heat of the meat equals the square of the hair plus the cube of the tube. [/QUOTE] Provided that the mass of the ass stays constant. ---
**Author:** ![SpectBrain](https://avatars.discourse-cdn.com/v4/letter/s/a87d85/32.png) [@SpectBrain](https://boards.straightdope.com/u/SpectBrain)\ **Post date:** [November 22, 2006, 9:35pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/39 "2006-11-22T21:35:07Z")
and to be serious y=mx+b to describe the slope of a line. Because that’s when the lights came on and I first started to understand math. ---
**Author:** ![Subway\_Prophet](https://avatars.discourse-cdn.com/v4/letter/s/ecb155/32.png) [@Subway\_Prophet](https://boards.straightdope.com/u/Subway_Prophet)\ **Post date:** [November 22, 2006, 9:49pm UTC](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280/40 "2006-11-22T21:49:01Z")
Dammit, both **KJ** and **SpectBrain** beat me to it. My #3 fave is y = y[sub]0[/sub] + (x-x[sub]0[/sub]) (y[sub]1[/sub]-y[sub]0[/sub]) /(x[sub]1[/sub]-x[sub]0[/sub]) …a.k.a. [linear interpolation](http://en.wikipedia.org/wiki/Linear_interpolation). [Previous page](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280.md?page=1) [Next page](https://boards.straightdope.com/t/what-is-your-favorite-equation/381280.md?page=3)