A long time ago, I was talking with Scott and he mentioned that the derivative of acceleration was called “jerk”.
It makes sense: the derivative of acceleration would be the rate of change of acceleration. If you change the acceleration of your car by slamming of the brakes, or by punching the accelerator, then you feel a jerk and your head snaps forward or backward.
I had a flash of inspiration. I said “Dude!” (I didn’t really say “Dude”). “I’ve totally gotta get a shirt that says ‘Don’t be a third derivative.’ (I didn’t really say “totally” either).
<nerdy (nerdier really) digression>
While jerk is a derivative of acceleration, acceleration is another derivative.
It starts with a formula like “y = f(x)” where y is time and f(x) is algebra math stuff.
This would describe the position of where an object is over time.
The first derivative of this formula would tell you the rate of change of position (velocity) of the object over time.
The derivative of velocity, or the second derivative of the position, tells you the rate of change of velocity (acceleration) over time.
This gets us to the derivative of acceleration, or the third derivative of position (jerk) of the object over time.
</nerdy (nerdier really) digression>
After the conversation, I googled “t shirt third derivative of acceleration”. The first few results were along the lines of “don’t be such a d3y/dx3“. I didn’t like that because it implies that the reader was already a jerk.
I googled some more and eventually found “don’t be a d3y/dx3“. Perfection.
The shirt has gotten a variety of reactions. Most folks have no idea what the “d3y/dx3” means – some of them ask me about it. One person looked at the shirt and asked if I was a teacher.
Outside of my family, only 2 people have recognized “d3y/dx3“. One was a former engineer who grew up to be a manager. (He seemed offended when I asked it he was an engineer). He asked me how much math I use in my work. I told him that I’ve never even taken a square root professionally.
The other was a college-aged woman who asked if my shirt meant “”don’t be a jerk”.
Stephen Squire 