# What is the Change in Acceleration Called? **URL:** \ **Category:** Factual Questions\ **Created:** [May 15, 2002, 7:53am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173 "2002-05-15T07:53:54Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Jim\_B](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jim_b/32/4338_2.png) [@Jim\_B](https://boards.straightdope.com/u/Jim_B)\ **Post date:** [May 15, 2002, 7:53am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/1 "2002-05-15T07:53:54Z")
I added my own input to a recent physics [question](http://boards.straightdope.com/sdmb/showthread.php?threadid=114565&goto=newpost) summitted by another board member. As you can see it has been a while since I’ve taken any physics course. But this question got me thinking. About Newton’s laws of motion. _Velocity_ is defined as the change in distance, or simply distance divided by time: D/T. When you look for the change in velocity in relation to time, you get _acceleration_ which is simply V/T–also variously defined as D/T/T and D/T^2. (Remember in the site I refer to, the acceleration due to gravity is given as 9.8m/sec^2.) Now, my question. _What is the change in **acceleration** in relation to time?_ What is it called–and how is it used? I recall hearing somewhere that Calculus plays a role in this all. That one equation is a derivative of another, which is itself a derivative of another and so forth. Does this have anything to do with my answer? TTFN:D ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 15, 2002, 7:57am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/2 "2002-05-15T07:57:16Z")
You could extend this again to wonder what is the name for the change of (rate of change of acceleration) and then the change of(change of (rate of change of acceleration)); it may be that nobody has ever bothered inventing a single-word term for that. ---
**Author:** ![grimpixie](https://avatars.discourse-cdn.com/v4/letter/g/ecb155/32.png) [@grimpixie](https://boards.straightdope.com/u/grimpixie)\ **Post date:** [May 15, 2002, 8:13am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/3 "2002-05-15T08:13:20Z")
> [@](#): > > \*Originally posted by Jim B. \* > **I recall hearing somewhere that Calculus plays a role in this all. That one equation is a derivative of another, which is itself a derivative of another and so forth. Does this have anything to do with my answer?** While **Mangetout** has made the point that the rate of change of acceleration is not (yet) a useful concept and therefore has not been given a name, you are correct that whatever it is called (lets call it **Eric** for the sake of sanity) it will be the derivative of Velocity with respect to time. **Eric** = [symbol]d[/symbol]v/[symbol]d[/symbol]t 🙂 ---
**Author:** ![Cabbage](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@Cabbage](https://boards.straightdope.com/u/Cabbage)\ **Post date:** [May 15, 2002, 8:22am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/4 "2002-05-15T08:22:34Z")
The third derivative of the position function is called _jerk_. That’s pretty standard. Beyond that, it’s not standard, but it’s not uncommon to see references to the following (which were created half-jokingly): 4th derivative: _snap_ 5th derivative: _crackle_ 6th derivative: _pop_. [http://math.ucr.edu/home/baez/physics/General/jerk.html](http://math.ucr.edu/home/baez/physics/General/jerk.html) ---
**Author:** ![substatique](https://avatars.discourse-cdn.com/v4/letter/s/f19dbf/32.png) [@substatique](https://boards.straightdope.com/u/substatique)\ **Post date:** [May 15, 2002, 8:24am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/5 "2002-05-15T08:24:30Z")
_change in something_ is often called _delta something_. the delta is a triangle with point upward; you know, the greek letter. i don’t know how to make one appear. perhaps grimpixie can enlighten me, since it knows how to make a lowercase delta. so _change in acceleration_ can be called _delta a_ or _^a_ (just pretend that’s a proper delta). i don’t think it’s strictly proper to say _delta acceleration_ or _delta velocity_, but all my physics profs have said _delta v_ or similar (rate of change of acceleration is less common). jim, i don’t think calculus will give you the **term** you are looking for, but it could certainly give you derivitive (and integral) **equations** with regard to _t_…as grimpixie said, i see. ---
**Author:** ![Skip](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@Skip](https://boards.straightdope.com/u/Skip)\ **Post date:** [May 15, 2002, 10:23am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/6 "2002-05-15T10:23:46Z")
In my high school physics lecture I was told that the common word for the change of acceleration is **Impulse**. Don’t know if it’s scientifucally correct but we used it in class… ---
**Author:** ![CzechHistory411](https://avatars.discourse-cdn.com/v4/letter/c/94ad74/32.png) [@CzechHistory411](https://boards.straightdope.com/u/CzechHistory411)\ **Post date:** [May 15, 2002, 10:32am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/7 "2002-05-15T10:32:13Z")
> [@](#): > > \*Originally posted by Skip \* > \*\*In my high school physics lecture I was told that the common word for the change of acceleration is **Impulse**. Don’t know if it’s scientifucally correct but we used it in class… \*\* Impulse is (according to my notes) defined at force multiplied by time. Also, delta acceleration would be change in acceleration over time, while the derivative in question would be the instantaneous rate of change. – CH ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [May 15, 2002, 11:53am UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/8 "2002-05-15T11:53:31Z")
I agree with jerk ---
**Author:** ![Undead\_Dude](https://avatars.discourse-cdn.com/v4/letter/u/e19adc/32.png) [@Undead\_Dude](https://boards.straightdope.com/u/Undead_Dude)\ **Post date:** [May 15, 2002, 12:15pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/9 "2002-05-15T12:15:24Z")
It is definitely **jerk**. I was taught that by at least 3 physics teachers. 🙂 IIRC correctly, impulse is a delta of _momentum_. ---
**Author:** ![Wikkit](https://avatars.discourse-cdn.com/v4/letter/w/c0e974/32.png) [@Wikkit](https://boards.straightdope.com/u/Wikkit)\ **Post date:** [May 15, 2002, 1:22pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/10 "2002-05-15T13:22:34Z")
> [@](#): > > \*Originally posted by grimpixie \* > **While Mangetout has made the point that the rate of change of acceleration is not (yet) a useful concept and therefore has not been given a name,** It is a useful concept when dealing with rockets and jet engines. The Argus engine on the V-1, for example, had increased thrust with increased velocity, so the accel of accel is useful. It’s also good for diagnostics in amateur rocketry; you can get an idea of how the grain is burning by how the acceleration changes. I’ve never heard it before, but jerk sounds good to me. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [May 15, 2002, 2:34pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/11 "2002-05-15T14:34:25Z")
A calculus teacher told us it was called **warp** , but maybe he was just a Star Trek geek… ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [May 15, 2002, 3:10pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/12 "2002-05-15T15:10:26Z")
jerk: a unit of change in acceleration sometimes used by engineers. This is not as silly as it sounds, because when we’re in a vehicle and feel a jerk, we are in fact experiencing a change in the acceleration of the vehicle. One jerk is equal to a change in acceleration of one foot per second per second in one second, that is, 1 ft/sec3. One jerk equals 0.3048 m/s3 or about 0.03108g /sec. [http://www.unc.edu/~rowlett/units/dictJ.html](http://www.unc.edu/~rowlett/units/dictJ.html) ---
**Author:** ![Undead\_Dude](https://avatars.discourse-cdn.com/v4/letter/u/e19adc/32.png) [@Undead\_Dude](https://boards.straightdope.com/u/Undead_Dude)\ **Post date:** [May 15, 2002, 6:34pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/13 "2002-05-15T18:34:33Z")
Strange to hear it described as a unit. I have heard it described not as a unit but as a general concept, as described here: [What is the term used for the third derivative of position?](http://math.ucr.edu/home/baez/physics/General/jerk.html) > [@](#): > > It is well known that the first derivative of position (symbol x) with respect to time is velocity (symbol v) and the second is acceleration (symbol a). It is a little less well known that the third derivative, i.e. the rate of change of acceleration, is technically known as jerk (symbol j). I guess there isn’t wrong with it being a unit also, esp since as an english system unit it is pretty worthless anyway. 🙂 ---
**Author:** ![SCSimmons](https://avatars.discourse-cdn.com/v4/letter/s/e495f1/32.png) [@SCSimmons](https://boards.straightdope.com/u/SCSimmons)\ **Post date:** [May 15, 2002, 7:03pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/14 "2002-05-15T19:03:47Z")
This could make a good Abbott and Costello routine. “What is change in acceleration called?” “Jerk.” “No need to call me names, I was just asking!” 😃 That said, I don’t remember any ballistics textbooks/problems I’ve seen giving this a name. It’s usually just referred to as da/dt. (And it really does come up a lot-even with a constant force behind it, the acceleration of a rocket increases over time as the fuel is spend and the total mass decreases …) ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [May 15, 2002, 7:07pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/15 "2002-05-15T19:07:43Z")
If you can’t see this post, I’ve given up after three tries. We were told that the jerk is what the human body is most sensitive to – perhaps the only motion that can be felt internally. Steady acceleration (cf. Einstein’s elevator) is difficult to feel without aural or visual clues, but when you’re getting jerked around, you know it. It also has application in looking at sports injuries. If I’d been the first to respond to this question, I would have had a strong temptation to just leave the response, “jerk”. ---
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [May 15, 2002, 7:30pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/16 "2002-05-15T19:30:33Z")
So the cardinal rule of the SDMB is “Don’t be a d[sup]3[/sup] **s** /dt[sup]3[/sup].” Interesting stuff. I was a physics major in college, and I have often wondered if there was a word for that. I even asked a prof once, and he didn’t know. The same professor said that “pickup” is the scalar equivalent of vector acceleration. Was he full of it?2 ---
**Author:** ![rsa](https://avatars.discourse-cdn.com/v4/letter/r/839c29/32.png) [@rsa](https://boards.straightdope.com/u/rsa)\ **Post date:** [May 15, 2002, 8:14pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/17 "2002-05-15T20:14:13Z")
Hey, **bibliophage** you may want to get one of these (from **Cabbage’s** link): > [@](#): > > In the aerospace industry they even have such a thing as a jerkmeter… Might make your job easier. 🙂 ---
**Author:** ![breaknrun](https://avatars.discourse-cdn.com/v4/letter/b/bbce88/32.png) [@breaknrun](https://boards.straightdope.com/u/breaknrun)\ **Post date:** [May 15, 2002, 9:49pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/18 "2002-05-15T21:49:44Z")
> [@](#): > > \*Originally posted by bibliophage \* > \*\*So the cardinal rule of the SDMB is “Don’t be a d[sup]3[/sup] **s** /dt[sup]3[/sup].” > \*\* Oh that just screams sig line to me. 🆒, **bibliophage** ---
**Author:** ![Undead\_Dude](https://avatars.discourse-cdn.com/v4/letter/u/e19adc/32.png) [@Undead\_Dude](https://boards.straightdope.com/u/Undead_Dude)\ **Post date:** [May 15, 2002, 10:32pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/19 "2002-05-15T22:32:41Z")
**bibliophage** , that is so beautifully geeky! 😃 ---
**Author:** ![bugg](https://avatars.discourse-cdn.com/v4/letter/b/ecae2f/32.png) [@bugg](https://boards.straightdope.com/u/bugg)\ **Post date:** [May 15, 2002, 11:32pm UTC](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173/20 "2002-05-15T23:32:16Z")
> [@](#): > > \*Originally posted by grimpixie \* > \*\* > > While **Mangetout** has made the point that the rate of change of acceleration is not (yet) a useful concept and therefore has not been given a name, you are correct that whatever it is called (lets call it **Eric** for the sake of sanity) it will be the derivative of Velocity with respect to time. > > **Eric** = [symbol]d[/symbol]v/[symbol]d[/symbol]t > > 🙂 \*\* For the sake of correctness, the value we’re talking about is the second derivative of velocity with respect to time, not the first. It is the first derivative of acceleration, however. Jerk! That’s actually a new one for me, but it sure is neat. As for the impulse issue, you guys are both right- it’s force times change in time and change in momentum. Is there a way to insert a delta on this group? Hmm? Well, can’t find one, so let d(x) read ‘delta x.’ Quick proof: F = ma F = md(v)/d(t) Fd(t) = md(v) Change in momentum equals force times the time over which the force acts. Cheers! (In the past two weeks I’ve taken a physics final and a calc final. Now begone!) F = d(p)/d(t) [Next page](https://boards.straightdope.com/t/what-is-the-change-in-acceleration-called/109173.md?page=2)