# What's the function 2nd derivative

Discussion in 'Personal' started by shakes1616, Jul 13, 2020.

1. ### shakes1616Established commenter

Any maths teachers who can say in simple terms what the function of the second derivative is. Is it rather banal? And why not just stop at the first one?

2. ### colacao17Senior commenter

I don't quite understand the question. You mean the derivative of a specific funtion?
Or do you mean in general what purpose does the 2nd derivative serve?

If the second, here's an example. The first deriviative of displacement with respect to time is velocity. The 2nd derivative is acceleration.

In general terms, the first derivative gives you the rate of change of one quantity with respect to another, the 2nd gives you the rate of change of rate of change which, even if it does not represent a specific quantity such as acceleration, is necessary if we want to predict how the original quantity will continue to change - we can't assume that its rate of change will remain constant.

knitone, Rott Weiler, nomad and 2 others like this.
3. ### shakes1616Established commenter

Thanks. I see but still a bit puzzled.
If a barman goes down to the cellar to change the barrel, can you use the 1st or 2nd derivative to calculate how long the beer will take to pour out of the tap in the city bar? And how do you do it

To choose a topical example, suppose you have a function that models the number of people who have been infected with coronavirus. The first derivative will tell you how many people are being infected at a given time, the second derivative will tell you how rapidly that number is increasing or decreasing (giving you the basis to determine R).

5. ### shakes1616Established commenter

Would Sigma 3.1U be such a model for no if infections where U is the current number of infected people and 3.1 is the number of people any person infected will infect

6. ### shakes1616Established commenter

What about derived words? From derivative, you can get derive. And from derive, you can get drive by adding an R. But how do such derivations pan out in the real world?

7. ### DodrosStar commenter

"Drive" doesn't derive from "derive". The former is Germanic in origin, the latter Latin.

8. ### shakes1616Established commenter

Oops lol. yeh but baddest derives from bad as in what's the baddest school you've ever been in ?lol

9. ### sbkrobsonStar commenter

I was perfectly fine with every single word in this thread until that!

10. ### oldsomemanStar commenter

Does this help..not that i understand it

11. ### Aquamarina1234Star commenter

Oh god it's all coming back to me. How much I hated physics.

Trekkie likes this.
12. ### shakes1616Established commenter

I meant take out the e sorree.

But what can you do with derived words seeing as they are not numbers? EG Drive---Dive-Div

So theoretically a second derivitive of Drive can be Div. LOL But what can one do with this?

13. ### S1a3t5u7r9nEstablished commenter

Calculus is a whole different world

14. ### racroesusStar commenter

Handle electromagnetism better.

gainly likes this.

16. ### gainlyStar commenter

Really? I teach maths and I haven't a clue what the OP is asking about.

Didn't we have a thread recently about someone claiming to be a maths teacher (A-Level Further Maths in fact)? It should have turned up in a search I did just now, but it didn't, leading me to believe it's been deleted.

That’s me

19. ### gainlyStar commenter

I think your comment was wasted on most people, but I appreciated it.

20. ### racroesusStar commenter

Thank you, kind sir!