The h Bar

Sir Cumference

21:00

@KyleKanos seems kind of useless then :/

"I had a Wii"

Kyle Kanos

No way

Homebrew +infinity

I've got a SNES EMU on there, so I can play any awesome game I want

(e.g., LoZ:LttP, FF 4,5 & 6, MMX, ...)

ACuriousMind

@KyleKanos "something"?

Kyle Kanos

@ACuriousMind I think it's a piece to a board game, but not sure since it's still in there

ACuriousMind

Ah, and you can't get it out?

Kyle Kanos

Correct

Sorta

I've not really tried

I need something long and thin, and I don't have any tools that could work

ACuriousMind

21:03

No Idea how heavy this thing is, but...plastic straw?

(I also don't know how broad the Wii slit is)

Kyle Kanos

Hmm. A straw might work.

I'll have to procure one. I think the midwife gave my wife one

Unsuccessful

ACuriousMind

The procurement or the removal of the alleged board game piece?

Kyle Kanos

The removal

ACuriousMind

Is the straw too soft or not the right shape?

Obliv

@acuriousmind have you ever taken a fluid-mechanics class/know much about the navier-stokes equations?

Kyle Kanos

21:19

@ACuriousMind Too soft, it seems

Bernard Meurer

@ACuriousMind Yo

How do those anti-static "guns" work?

It seems too good to be true

ACuriousMind

@Obliv I know nothing about hydrodynamics

@BernardMeurer I have never heard of them

Bernard Meurer

amazon.co.uk/Milty-Zerostat-3-Anti-Static-Gun/dp/B0033SHDSS

@ACuriousMind Supposedly you just point them at whatever you want to decharge

and you press the trigger

and God himself, comes from the sky and takes the static with him to heaven

heather

@Secret, they are currently lower level questions, but we welcome questions of any level, and we would welcome that question, especially if they added more of their own work.

ACuriousMind

@BernardMeurer Quick googling tells me that there appears to be a piezo-electric cyrstal inside that is struck by a hammer when you press the trigger, which then releases charges that supposedly neutralize the static charge on the surface. No idea how well that works in practice

heather

21:32

@DanielSank, good news: I've made it through derivatives and integrals unscathed. I need to do a little more practice with them, and some work with limits, but otherwise I think I've got basic calculus down fairly well. I'm going to try multivariable calculus next - I found a nice series of YouTube videos on it.

Bernard Meurer

@ACuriousMind I've heard it works, but I don't trust Audiophiles

An anti-static gun seemed like crackpottery

heather

would anyone mind giving an example of a derivative/integral problem that might be used in classical mechanics so I can try my hand at it?

Bernard Meurer

@heather Can it be the mechanics of my poor grades? :P

heather

@BernardMeurer, they can't be that bad =P

Bernard Meurer

@heather They're cancer. I have 10/20 in chemistry :P

And God only knows what I'll get in Analysis

heather

21:35

@BernardMeurer, ooh, I'm sorry about the chemistry grade. You'll be fine in analysis though, I'm sure!

Obliv

@heather find the work required to pull up a 25m rope with linear mass density 1 kg/m with a 25kg sandbag attached to the bottom that leaks at a rate of 1kg/s

I remember something like that in my old single var calc txtbook

Bernard Meurer

I gotta change majors

CEng is just utter bullshit

heather

oh, boy, okay I'll give it a whirl @Obliv, thanks for the problem

Obliv

np gl

DanielSank

@heather you learned calculus in one day?

4

heather

21:38

@DanielSank, there was a really good YouTube video series I found that taught it

it explained it pretty clearly

DanielSank

@heather sure. Solve for the position versus time of a mass on a spring with initial position 0 and initial velocity $v$.

Bernard Meurer

I'm 3 months into Calc and I haven't learned a thing yet

DanielSank

@KyleKanos don't care. I might try netplay at some point.

Bernard Meurer

@heather Ryan says "Heather is basically Feynman"

heather

@BernardMeurer, 1. no way am I Feynman =P 2. sorry, who's Ryan?

Bernard Meurer

21:40

@heather @0celo7 is Ryan

heather

@BernardMeurer, oh, I see

@0celo7, thank you =)

Obliv

I forgot some information for that problem @heather lol, you pull the bag up at 2 m/s

heather

@Obliv, okay, thanks =)

Bernard Meurer

$$||f^\epsilon||_\infty=\operatorname{ess}\sup_{x\in\Bbb R^n}|f^\epsilon( x)|=\operatorname{ess}\sup_{x\in\Bbb R^n}|\int_{\Bbb R^n}\eta^\epsilon(x-y)f(y)dy|\le \operatorname{ess}\sup_{x\in\Bbb R^n}||f||_\infty\int|\eta^\epsilon(x-y) |dy=||f||_\infty$$

Obliv

if you didn't have that information i think you could just wait until the sandbag emptied then pull it up lol

Bernard Meurer

21:41

@ACuriousMind Is that right

Obliv

@DanielSank you should try 'faster melee' it's a different type/version of dolphin netplay that apparently has less input lag than a crt.

just have to join the discord and download the latest version I think.

Sir Cumference

@obe I mustache you a question

user218912

lol

Kyle Kanos

@DanielSank Still haven't tried netplay

Sir Cumference

@obe But I'm shaving it for later

Kyle Kanos

21:44

On anything for the Wii

heather

I know I'm doing something wrong here and I haven't even gotten to the actual calculus yet...

Work = Force $\times$ Displacement

and Force = mass $\times$ acceleration

and Displacement = $v_0t+ \frac{1}{2}at^2$

Sir Cumference

@heather I don't think it's possible to learn calc in a day

user218912

I learned calc in ~3 days.

Bernard Meurer

@obe Oh shut up

heather

and I know that the initial velocity is 2 m/s

user218912

21:47

@BernardMeurer I did, basic calc.

heather

and that there is no acceleration, right, because it is moving at a constant rate

Sir Cumference

@BernardMeurer Ahaha

heather

@SirCumference, why not?

Sir Cumference

@heather Have you learned all the derivative rules?

Kyle Kanos

Woot...answered my first question in 7 months!

Bernard Meurer

21:47

@heather What is $\int_0^L sin(n\pi x/L)sin(m\pi x/L) dx$, where $n$ and $m$ are integers?

heather

so the displacement equation turns into $d = v_0t$

Bernard Meurer

From Ryan :P

Sir Cumference

@BernardMeurer God, fix that LaTeX

Kyle Kanos

@BernardMeurer 0

heather

@BernardMeurer, I'll start solving it after I figure out the other two

Sir Cumference

21:48

$\int_0^L \sin(\frac{n\pi x}{L}) \sin(\frac{m\pi x}{L}) \mathrm{d}x$

Obliv

@heather the important part is that the mass varies as you are pulling it up. Also, the acceleration that you are concerned with is that of gravity. Remember, there is no work done on an object if there is no force.

Bernard Meurer

@KyleKanos "Go back to high school"

heather

@Obliv, right, I forgot about that. So there is acceleration, duh. Okay, thanks!

Sir Cumference

@heather Did you only learn power rule?

heather

@SirCumference, I learned about the product and sum rule, or is that not what you're talking about?

Obliv

21:49

And to be honest, this problem isn't very much calculus as it is physics/general problem solving.

Kyle Kanos

@BernardMeurer No way man. High School sucked

Sir Cumference

@heather Basically subtracting from the exponent and bringing it down, for derivatives

Bernard Meurer

@KyleKanos Meh, university sucks too

user218912

everything sucks

Sir Cumference

@obe :(

heather

21:50

@SirCumference, no I didn't learn the power rule...I'll look it up.

Kyle Kanos

@BernardMeurer And I'm glad to be done with that too

Bernard Meurer

Let's be honest here guys, life's a bottomless pit of pain and suffering

Kyle Kanos

And grad school

Sir Cumference

@heather You're better off learning it in order

Kyle Kanos

And I'm very happy to be working

Sir Cumference

21:50

Don't go looking for abritrary things

heather

@SirCumference, I don't want to wait four years to learn about what I want to learn about.

Sir Cumference

It'll make it harder to learn

@heather No, I mean learn the calc concepts in order

Bernard Meurer

@heather That's good

user218912

no

user218912

order is bad

Sir Cumference

21:51

@obe Stop

Bernard Meurer

@obe You're a dirty anarchist

Sir Cumference

You're not helping

heather

@SirCumference, oh. I am trying too.

Sir Cumference

@heather So I'd hold off on whatever you don't know until you get to it

Obliv

@bernard what's wrong with anarchy

Bernard Meurer

21:52

@Obliv It's for kids

Obliv

false argument

Sir Cumference

@BernardMeurer Silly rabbit, anarchy is for kids

Kyle Kanos

Anarchy is for people who think they want no order but really just want to be in charge themselves

3

Bernard Meurer

@heather Try learning maths the way I learned programming, be the guinea pig :P

@heather Pick a problem, learn the tools to solve it, solve it, repeat

Sir Cumference

@heather Did you finish algebra 2 and trig yet?

heather

21:53

I taught myself trig

user218912

best way to learn anything is to jump into the deep end.

heather

and most of algebra II

Sir Cumference

@heather Learn it all first

@heather And the inverse trig functions?

Bernard Meurer

@heather What's the sine of 2$\pi$?

Sir Cumference

With the unit circle definitions?

Kyle Kanos

21:54

@BernardMeurer 0

Obliv

@kylekanos Do you think anarchy is only achievable through an external influence? I think nature just orders things by itself (at least in the context of animals, what with the DNA & biological functions)

Sir Cumference

@BernardMeurer 12

Bernard Meurer

@KyleKanos Wrong, it's 12

2

@SirCumference Perfect

heather

@BernardMeurer, 0

Bernard Meurer

@heather What's with you people, 12!

2

dmckee

21:55

@Obliv The thing that is, in all seriousness, wrong with anarchy is that no one has shown an example of a stable anarchy without being imbeded in a surrounding non-anarchic sociaety that provides a norm of peace and order.

user218912

it gets dark so early now

Obliv

@sirC if she wants to learn some calc let her. She's going to fill the holes eventually, I'd hope, with like 4 years of hs ahead of her.

Kyle Kanos

@Obliv I don't think anarchy is achievable because humans are too domesticated.

Sir Cumference

@Obliv It'll be easier if she knows algebra first

dmckee

Vernor Vinge has offered some fiction portrayals of how that might work, but no one knows for sure.

Sir Cumference

21:55

Really lots of things will be easier if she learns algebra first

heather

I'm stuck with the physics part of your problem @Obliv, I don't know how to calculate the acceleration.

Bernard Meurer

In a sine you just take one leg and the hat off the $\pi$ and then the number multiplying it goes after that. So $\sin(2\pi)=12$

3

Sir Cumference

@BernardMeurer Oh god XD

heather

@SirCumference, I'd like to think I know algebra well enough to carry on. I have most of it, if I come up against a gap, I can go back and fill it in.

Sir Cumference

@heather I'd still learn all of algebra first

user218912

21:56

most calc books will cover the algebra you need in the back.

Sir Cumference

You won't know when you come across a gap, sometimes

user218912

so just look at that

Sir Cumference

Even outside of calc, algebra can be helpful if you know its entirety

Obliv

@dmckee do you mean an example in nature? Surely it's not necessary to provide a real example of anarchy when it's just a theorized way of life (or death). Doesn't mean it can't happen, does it?

Sir Cumference

You won't know what you missed if you don't finish it

heather

21:57

if an object's mass is changing, its acceleration is changing

Sir Cumference

It'll really only help you, and a lot

heather

@SirCumference, I do have the actual class Algebra II next year

Obliv

@kylekanos Well, I think there are ways to reduce the order (global crises,natural disasters, etc) but to have no order might be impossible.

heather

which is key to the whole equation

dmckee

@Obliv We have plenty of examples, most of them either develop into tribal system or get conquered. Sometime both.

Sir Cumference

21:58

Obliv

@heather The acceleration is not changing. it's always 9.8 m/s

Sir Cumference

In case anyone missed out on this gem

Kyle Kanos

@Obliv As soon as you have 2 people, one will naturally become the de-facto leader

user218912

@heather that doesn't mean anything

Obliv

the force is changing, though.

dmckee

21:58

The basic problem is that organized humanity is more powerful than unorganized humanity.

heather

@Obliv, oh, wait, I know what I did wrong

dmckee

So unless all the organized types are willing to let you mremain unorganized you're in trouble.

heather

okay, rewinding =)

Sir Cumference

@Obliv Didn't realize she meant gravitational acceleration

Somehow...

dmckee

There are a few counterexamples, but all of them recieve the benifit of protection from a surounding organized society.

So, the fun part is trying to figure out how to get a resistance to organized attack that will work in a reasonably anarchic society.

And that's non-trivial.

Obliv

22:00

@kyleK @dmckee so basically you're saying it's an incompatible way of life for people

Kyle Kanos

@Obliv Correct

dmckee

More like the few #@()*&%#*s among us ruin it for everybody else.

Obliv

has the fundamental reason to do with a well-ordering of desires within the genetic makeup of people?

dmckee

"This is why we can't have nice things..."

Sir Cumference

@heather Btw we were kidding about the whole $\sin(2π) = 12$ thing...

Kyle Kanos

22:02

@Obliv Honestly couldn't say. I just think people are more comfortable with rules being in place

heather

@SirCumference, I thought so, judging by the number of stars by the statement =P

Obliv

@kyleK is anarchy a system with no government, or one without order? I thought it was the latter, which is why i asked that.

user218912

why are we even talking about anarchy?

user218912

i meant no order as in don't learn stuff in order.

Obliv

i.e something like the lifestyle of lions would still be non-anarchy.

user218912

22:04

and i was joking

Obliv

@obe well I asked the question because it was brought up. it's nice to hear opinions from people sometimes.

Kyle Kanos

@Obliv I think it colloquially is used to mean no "big" government, but it's supposed to mean no government at all

dmckee

@Obliv Self organization that you can opt out of without any cost beyond not being part of the ordered activity is generally included under the notion of "anarchy".

Sir Cumference

@dmckee Woah

Serious question

How long have you been a mod?

I never noticed your blue text before...

user218912

do you ever notice anything?

Obliv

22:09

Hmm okay I see then. I might be wrong, but, I think somalia was under an anarchy at some point in the near past. Never really confirmed this but this isn't a counter-example to your argument because it existed inside of a non-anarchy system, right? @dmckee

Sir Cumference

@obe no but seriously how long has he been a mod?

Kyle Kanos

@SirCumference since the beginning of Physics...

Sir Cumference

@KyleKanos whoa....

heather

@Obliv, so here's the equation I've got so far (I simplified a bit from the original):
$W = (245 \text{kg m/s} + 9.8(-t)\text{m})(\frac{11.8t\text{m}}{2})$

Kyle Kanos

At least I think so

heather

22:10

where $t$ is of course time, $W$ is work, and the text is the units

Obliv

what is $m$ @heather

heather

@Obliv, meters

and kg m/s is kilogram meters per second

dmckee

@Obliv It didn't have a internationally recognized governement, but it did have half a dozen clans and strongmen. Most people had someone who could tell them what to do most of the time.

That's called "anarchy" by people who think recognized governments are special, but not by people who take the concept seriously.

And the fact that those clan leaders and strongmen appeared and took power is exactly the problem.

You need to figure out a way to not have a centralized government and still keep those people from popping up.

And that's hard.

Sir Cumference

@dmckee Question, our astro prof said that everyday matter is nearly degenerate

Is that true?

As in, almost all the fermions are near their lowest energy states

dmckee

@SirCumference Well, the atoms are mostly not excited, so that's an defensible position to a certain way of thinking.

And exclusion plays a role in the structure and behavior of solids.

Sir Cumference

22:15

@dmckee Cool, because he took out a coin and said "this is degenerate"

dmckee

But I wouldn't use of condone the phrase myself.

heather

@Obliv, am I doing this really wrong, or is it alright?

Obliv

@heather working through it now, but I don't think that's right (or it's in a form I can't quite recognize)

heather

@Obliv, okay, should I post the work I did?

Obliv

that would be helpful, yes.

dmckee

22:16

Simply because I like to ephasize that "degenerate matter" has a different set of properties from ordinary solids.

Sir Cumference

@dmckee Simply because all the energy states from the ZPE to the Fermi energy are occupied?

Obliv

I got $M_{total} = M_{sandbag} + M_{rope}$ where $M_{sandbag} = 25 - t$ and $M_{rope} = 25 - 2t$ so we have $M = 50 - 3t$ , is this what you had @heather

Sir Cumference

That leads to such a huge difference in properties, from ordinary matter?

I mean, you just said that the atoms are mostly not excited

heather

@Obliv, oh, I didn't add in the rope's weight, darn, okay, I'll do it again

dmckee

@SirCumference Because there are few accessible modes for a lot of constituent particles.

But I have to go. Take care.

Sir Cumference

22:17

@dmckee Ah, makes sense

@dmckee Bye

@obe Question

Obliv

.

@heather okay let me know when you want the solution

Sir Cumference

@Obliv Please use \mathrm{d}x

It looks prettier

heather

@Obliv, okay, thanks

Obliv

@dmckee but not impossible ;) But for all practical purposes and being relevant to reality, I agree.

Kyle Kanos

{\rm d}x also works

Sir Cumference

22:19

@KyleKanos Lame...

Obliv

$\text{d}x , dx, \mathrm{d}x$

Sir Cumference

\mathrm is the way to go

Obliv

you could just use \text{}?

Sir Cumference

@Obliv No, mathrm is for symbols

Or units

Text is for words

Obliv

it's the same exact thing.

user218912

22:20

what

Sir Cumference

@Obliv No, mathrm is more mathy, can't you read it?

Kyle Kanos

@SirCumference Only because it's more "standard" or something

Obliv

$\text{d}x$ <--- text $\mathrm{d}x$ <----- mathrm

literally no difference.

Sir Cumference

@KyleKanos I just proved mathrm is specifically made for math

Proof: it has math in it

Kyle Kanos

They do different things really. \mathrm takes arguments, \rm modifies the equation environment

heather

22:21

@Obliv, okay, now I've got $W = (490 \text{kg m/s} - 29.4t\text{m})(\frac{11.8t\text{m}}{2})$

Sir Cumference

82

Q: Is there a preference of when to use \text and \mathrm?

I'm unsure of when it is preferable to use \text versus \mathrm, is there some unwritten rule about the use of these? For example, I saw the following code in a math post: \frac{\mathrm{lcm}(m,n)}{\mathrm{gcd}(m,n)}\quad\text{divides}\quad \frac{\mathrm{lcm}(m,n)}{|\langle x\rangle\cap\langle ...

Better detail than I can

Kyle Kanos

3

Q: How to write maths symbols

I have written in my work $X^{+},\,\rm{e}^{X},\,|X|^{p}$. Why is the second and third term not in italics?

math-mode symbols

heather

I realized something else I did that may be kind of funky: I reduced it such that for all $t$ you ignore the units (I assumed $t$ was in seconds and simplified in that manner, which I probably shouldn't have done).

I keep making all these stupid mistakes. I'll rework it without the $t$ weirdness.

Obliv

what is that 11.8/2 term on the right @heather

can you show me the integral?

Sir Cumference

$$\Huge \color{purple}{\LaTeX}$$

heather

22:24

@Obliv, okay, now I know I'm doing this really wrong.

Here's what I did:

$F = ma$
$d = v_0t+\frac{1}{2}at^2$
$W = F\times d$
$m = 25 - t+25-2t$
$m = 50\text{kg} -3t$
$F = 9.8 \text{m/s}(50\text{kg}-3t)$
$d = 2 \frac{m/s}t+\frac{1}{2}9.8\text{m/s}t^2$
$W = (9.8\text{m/s}(50\text{kg} - 3t))(2\text{m/s}* t+\frac{1}{2}((9.8\text{m/s}) (t^2)))$

Obliv

@heather oh my. yes, that is wrong. But, you had the right idea with W = f*d

Sir Cumference

@heather Be sure to use \times instead of *, in LaTeX

heather

@Obliv, where did I go so wrong?

Obliv

You dont' need to invoke any kinematic equations. We know the distance that you're pulling the rope. It's going up 25 meters, the rope length. That's how you have the mass of the rope as 25 - 2t (the mass during the whole trip)

heather

right

and you're pulling it at 2 m/s

Obliv

22:30

The force of gravity acts during the whole trip up, right?

heather

sright

right

so if $W = F\times d$

Bernard Meurer

(Assuming gravity is real)

heather

and the displacement is 25 meters?

Obliv

The speed at which you pull it up is irrelevant, except to determine the variable mass of the sandbag. You could pull it up at 100 m/s or 1 m/s, the work will be the same. You are familiar with this concept? @heather

heather

@Obliv, I don't really know much of any classical physics, sorry. I didn't know that.

Obliv

22:32

Well, we know the mass varies during the trip with the given relation M = 50 - 3t and at each moment in time we have a different mass and thus a varying force. If the force varies, the work will vary, in this situation. That's where the integral comes in.

heather

so F = ma, then we know that it'd be F = (50kg - 3t)(9.8 m/s) and then it'd be that times 25m?

Obliv

@heather well, that's very important to know lol. It's $W = \int F~\mathrm{d}x$ which say nothing about time, assuming a is constant.

heather

@Obliv, I'm confused now, how did we get the integral?

Obliv

Not quite, we have a varying force at each time interval that we pull it up. It gets easier to pull up as we get closer to the top. So, we must take the limit to infinity of a riemann sum of the forces at each interval. Can you picture this?

Oh you didn't know the integral definition of work D: that's very important for this problem!

heather

@Obliv, yeah...sorry!

Obliv

22:36

It's fine. Did you go over the definition of an integral by taking the limit of riemann sums when you learned calc, btw? @heather

2physics

Hello everybody

heather

@Obliv, well, I know that the Riemann sum has to do with using rectangles of a specified width just under and just over the curve you are trying to find the area of, but beyond that, not really.

And then as the width of the rectangles approaches zero, the more and more accurate your area calculation gets.

Obliv

Okay. So, let's say we had a graph of the force w.r.t time during the trip. You agree it would look like a line with y-intercept y = 50 and a slope of -3?

Yes, exactly.

heather

I suppose so, yes

yes it would

Obliv

If you took a finite amount of rectangles to sum the forces during the whole trip and multiply that by the acceleration, you agree it would lead to a close-but not completely accurate result?

heather

22:40

yes

2physics

I have a simple question, please help: what does it mean when angular frequency is expressed in electron volts? and why is it for?

Obliv

Well, that's why there is an integral. If the force was constant the whole time (suppose the bag wasn't leaking and the rope was massless), you wouldn't need an integral, but for the times when it isn't constant, it's necessary.

So now, we know the precise equation for the force, that is $F = (50-3t)(9.8)$. We just need to integrate this over some interval. Can you think of some interval?

heather

a time interval? a second, maybe?

or, well, actually, no

we'd do it over the time it takes to pull the rope up, right?

Obliv

Exactly. That equation yields the exact force at each time $t$ during the interval. We need to sum these forces during the trip to get the work done.

heather

12.5 seconds, right? because 25m of rope, and 2m/s is the speed you are pulling at

Obliv

22:43

we'd need an infinite amount of slices of time so we have something of the form $\int_a^b F~\mathrm{d}t$ where $a,b$ is the beginning and end of the trip in terms of time.

yep. you got it.

heather

oh, so $\int^{12.5}_0 (50 - 3t)(9.8) dt$?

Obliv

yes

heather

=D okay, I'll solve that

one moment

ACuriousMind

0

Q: Would it have been possible to send a manned mission to Mars using Apollo technology?

To clarify, I am writing a science fiction story in which a manned Mars mission in 2025 discovers a previous manned mission to Mars sent in the 1990's using modified Apollo lunar technology. Even though it is science fiction I want my story to be as scientifically accurate as possible. For exampl...

space-mission

^engineering?

Sir Cumference

@ACuriousMind Is engineering not a part of physics?

ACuriousMind

22:53

@SirCumference No. One of our close reason is explicitly about a question being about constructing a solution to a particular problem using science (which is engineering) instead of about the natural science of how the world works (which is physics).

Sir Cumference

@ACuriousMind So applied physics isn't physics?

Only theoretical physics counts?

ACuriousMind

No. Experimental physics also counts. But applied physics is engineering.

Sir Cumference

@ACuriousMind Never heard someone say "Applied physics isn't physics"

ACuriousMind

Now you have.

Sir Cumference

@ACuriousMind Now I know.

Obliv

22:55

It isn't though @sirc is it the case that sports (an application of setting up rules for a game) are the same thing as theorizing games?

Sir Cumference

@Obliv You gotta be more specific when you say "games"

Sports are specifically meant for exercise

Obliv

Sports are physical games basically

Sir Cumference

@Obliv Nah, chess is a sport

That's mental exercise

Obliv

Eh I'm not getting into this lol I do not think chess is a sport in the usual definition of the word. A mental sport, competitive game, game, sure.

DanielSank

@heather do your calculations with symbols instead of numbers.

heather

23:00

@DanielSank, for your problem or Obliv's problem?

DanielSank

@heather any problem.

This is one of those really important habits that makes science/math a lot easier.

heather

@DanielSank, use symbols instead of numbers...okay, I'll try it.

2physics

nobody can help????

Obliv

I agree with Daniel even though I hardly ever do it myself lol

heather

I'm doing something really wrong, I'm getting a negative number (::sighs::) I'm thinking I need more practice =)

work is not negative =P

oh, wait, I see what I did wrong

doing it again

Obliv

23:17

I think the answer is around 4000 joules. Make sure you're separating the integral and performing the power rule correctly. Have to do a lab now so I leave u in the good hands of hbar @heather gl

heather

@Obliv, thank you for the problem and help!

have a good day

okay, so given the integral $\int^{12.5}_0 (50-3t)(9.8) dt$

you can then have $\int (50 - 3(12.5))(9.8) dt - \int (50 - 3(0))(9.8)$, right?

then I need to use the product rule...

Obliv

Noon Heather use the fundamental theorem of calculus pt 2

Noo** argh phone corrections.. $\int_a^b f (x) dx = F (b) - F (a)$ where F is the antiderivative of f

@heather And now I am off. Np

heather

@Obliv, okay, thank you for all your help!

Kyle Kanos

Wonder if I can hit 20k before I go back to work

That's only like 1k rep in about 10 days

Bernard Meurer

@KyleKanos If I ever drop by SC will you buy me ice cream?

heather

23:32

so confused by integration. I clearly have not got it. =/

Kyle Kanos

@BernardMeurer Probably not, I'm not in SC anymore

Bernard Meurer

@KyleKanos :(

heather

I wonder if I understand differentiating as much as I thought I did...

Bernard Meurer

23:51

@heather "Remember your Banach space rules"

heather

what, we never did banach spaces =P

though there was many a mention of them =D

Kyle Kanos

@heather Probably because they're fake

heather

banach spaces aren't real?

=(

rob

@heather No, but you can anagram the letters in "Banach-Tarski" to make "Banach-Tarski Banach-Tarski"

3

Bernard Meurer

@KyleKanos $L^p(\Omega, \mu)$

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