# What's a change in jerk called? **URL:** \ **Category:** Factual Questions\ **Created:** [February 17, 2011, 6:04pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724 "2011-02-17T18:04:08Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![TravisFromOR](https://avatars.discourse-cdn.com/v4/letter/t/cc9497/32.png) [@TravisFromOR](https://boards.straightdope.com/u/TravisFromOR)\ **Post date:** [February 17, 2011, 6:04pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/1 "2011-02-17T18:04:08Z")
I’m not sure how to make myself clear here, but I’ll try: A change in position is velocity. A change in velocity is acceleration. A change in acceleration is jerk. What do you call a change in jerk? ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [February 17, 2011, 6:05pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/2 "2011-02-17T18:05:03Z")
An election. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [February 17, 2011, 6:06pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/3 "2011-02-17T18:06:07Z")
Actuall: jounce or snap, per wikipedia. But I don’t think it’s as accepted as jerk. Also per wikipedia the higher orders above jounce or snap are crackle and pop, which are obviously even less accepted than jounce. ---
**Author:** ![Darth\_Panda](https://avatars.discourse-cdn.com/v4/letter/d/ee7513/32.png) [@Darth\_Panda](https://boards.straightdope.com/u/Darth_Panda)\ **Post date:** [February 17, 2011, 6:31pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/4 "2011-02-17T18:31:40Z")
4th derivative. ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [February 17, 2011, 6:34pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/5 "2011-02-17T18:34:26Z")
> [@Ludovic](#): > > An election. Bravo! Bravo, Bravo! Bravo! ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [February 17, 2011, 6:42pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/6 "2011-02-17T18:42:03Z")
> [@Ludovic](#): > > An election. I read that as “An erection” and thought, yeah, that’s about right. ---
**Author:** ![spenczar](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@spenczar](https://boards.straightdope.com/u/spenczar)\ **Post date:** [February 17, 2011, 6:43pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/7 "2011-02-17T18:43:18Z")
Incidentally, there are some deep reasons for why we only generally care about stuff up to acceleration. If higher derivative motions terms are relevant in the equations of motion for something, then the things Hamiltonian can reach arbitrary energies, which will cause it to spontaneously produce huge amounts of particles and quickly become catastrophic. See here: [http://physics.stackexchange.com/questions/4102/why-are-only-derivatives-to-the-first-order-relevant](http://physics.stackexchange.com/questions/4102/why-are-only-derivatives-to-the-first-order-relevant) ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [February 17, 2011, 8:59pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/8 "2011-02-17T20:59:46Z")
> [@Ludovic](#): > > An election. I was gonna say, “An inauguration,” but yours works, too. ---
**Author:** ![flano1](https://avatars.discourse-cdn.com/v4/letter/f/f14d63/32.png) [@flano1](https://boards.straightdope.com/u/flano1)\ **Post date:** [February 17, 2011, 9:32pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/9 "2011-02-17T21:32:18Z")
Thanks very much Ludovic! Coke out of both nostrils! ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [February 17, 2011, 10:05pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/10 "2011-02-17T22:05:32Z")
> [@spenczar](#): > > Incidentally, there are some deep reasons for why we only generally care about stuff up to acceleration. If higher derivative motions terms are relevant in the equations of motion for something, then the things Hamiltonian can reach arbitrary energies, which will cause it to spontaneously produce huge amounts of particles and quickly become catastrophic. See here: [http://physics.stackexchange.com/questions/4102/why-are-only-derivatives-to-the-first-order-relevant](http://physics.stackexchange.com/questions/4102/why-are-only-derivatives-to-the-first-order-relevant) [Supposedly](http://www.phys.ncku.edu.tw/mirrors/physicsfaq/General/jerk.html), the Hubble Space Telescope engineers put limits on m/s^4. I’ve never seen an explanation why, but my personal theory is this: when considering the linear aspects of angular motion, you tend to get one more derivative. A constant angular velocity means that points on the edge experience a linear acceleration. An accelerating angular velocity means points on the edge experience jerk. Hubble rotates around to aim, so obviously they care about this kind of thing. So if the Hubble engineers clamp angular jerk–and this is a good idea, since too much jerk can cause undue stresses on a structure–then this is equivalent to saying there is a clamp on jounce/snap/etc. At least that’s my personal explanation. But I’m no physicist. ---
**Author:** ![magellan01](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@magellan01](https://boards.straightdope.com/u/magellan01)\ **Post date:** [February 17, 2011, 10:18pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/11 "2011-02-17T22:18:23Z")
> [@Ludovic](#): > > An election. SUPER-bravo! ---
**Author:** ![spenczar](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@spenczar](https://boards.straightdope.com/u/spenczar)\ **Post date:** [February 17, 2011, 10:29pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/12 "2011-02-17T22:29:23Z")
> [@Dr.Strangelove](#): > > [Supposedly](http://www.phys.ncku.edu.tw/mirrors/physicsfaq/General/jerk.html), the Hubble Space Telescope engineers put limits on m/s^4. > > I’ve never seen an explanation why, but my personal theory is this: when considering the linear aspects of angular motion, you tend to get one more derivative. A constant angular velocity means that points on the edge experience a linear acceleration. An accelerating angular velocity means points on the edge experience jerk. Hubble rotates around to aim, so obviously they care about this kind of thing. > > So if the Hubble engineers clamp angular jerk–and this is a good idea, since too much jerk can cause undue stresses on a structure–then this is equivalent to saying there is a clamp on jounce/snap/etc. > > At least that’s my personal explanation. But I’m no physicist. Leave it to the engineers to ruin good physics. Bah. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [February 17, 2011, 10:46pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/13 "2011-02-17T22:46:56Z")
Rollercoaster designers also pay attention to the 3rd and 4th time derivative of position. Apparently it’s these higher order derivatives that give a rollercaster that ‘out of control’ feeling. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [February 17, 2011, 11:43pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/14 "2011-02-17T23:43:57Z")
> [@Ludovic](#): > > An election. Well done, sir. Well done, indeed. ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [February 18, 2011, 12:23am UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/15 "2011-02-18T00:23:49Z")
Back in school, we were told the 4th, 5th, and 6th derivatives were “snap, crackle, and pop”. ---
**Author:** ![Noel\_Prosequi](https://avatars.discourse-cdn.com/v4/letter/n/b19c9b/32.png) [@Noel\_Prosequi](https://boards.straightdope.com/u/Noel_Prosequi)\ **Post date:** [February 18, 2011, 3:56am UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/16 "2011-02-18T03:56:30Z")
> [@spenczar](#): > > Incidentally, there are some deep reasons for why we only generally care about stuff up to acceleration. If higher derivative motions terms are relevant in the equations of motion for something, then the things Hamiltonian can reach arbitrary energies, which will cause it to spontaneously produce huge amounts of particles and quickly become catastrophic. See here: [http://physics.stackexchange.com/questions/4102/why-are-only-derivatives-to-the-first-order-relevant](http://physics.stackexchange.com/questions/4102/why-are-only-derivatives-to-the-first-order-relevant) This sounds fascinating, but I don’t follow it, and I can’t follow the explanation in the link. “…then the things Hamiltonian can reach arbitrary energies..” doesn’t read well to me (but of course I am missing something). Any chance of a dumbed down explanation? ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [February 18, 2011, 5:47pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/17 "2011-02-18T17:47:55Z")
> [@Ludovic](#): > > An election. Dammit, I _just_ thought of that joke while looking at the index, and opened this thread just to make it. Way too late, I see – it was the very first response. Kudos! ---
**Author:** ![notfrommensa](https://avatars.discourse-cdn.com/v4/letter/n/f14d63/32.png) [@notfrommensa](https://boards.straightdope.com/u/notfrommensa)\ **Post date:** [February 18, 2011, 7:28pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/18 "2011-02-18T19:28:49Z")
somehow “Term Limits” has to be an application. ---
**Author:** ![Skammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skammer/32/143_2.png) [@Skammer](https://boards.straightdope.com/u/Skammer)\ **Post date:** [February 18, 2011, 7:42pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/19 "2011-02-18T19:42:08Z")
> [@Ludovic](#): > > An election. Aww, I was 90 minutes late. That was exactly my reaction to the OP. Kudos. ---
**Author:** ![Snickers](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Snickers](https://boards.straightdope.com/u/Snickers)\ **Post date:** [February 18, 2011, 7:54pm UTC](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724/20 "2011-02-18T19:54:07Z")
I think \*\*Ludovic \*\*deserves some sort of SDMB award or something - that was a right fine response, sir. [Next page](https://boards.straightdope.com/t/whats-a-change-in-jerk-called/571724.md?page=2)