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4:13 PM
@Loong Thanks. Got it!
It seems to be experimentally verified
Rather than something theoretical
 
user228700
This laptop is <3 @JohnR: Can't help but shout "Thank YOUUUU" :-)
 
@Kaumudi.H still impressed with the laptop!
 
user228700
:-) Yes, of course.
 
user228700
It is still marvellous that this laptop sits here, in my room.
 
I glad it's been worth while. My main concern was that having to learn physics with a phone as your only form of Internet access was a really hinderance.
 
user228700
4:17 PM
If you would've told me at the beginning of last year that I'd make friends from all across the globe and that one of them would send me an effing laptop, I would've asked "Are u high?"
2
 
My two new laptops arrived today. One of them is an ultraportable, a Dell E6230, and it's soooooooo cute! :-)
 
user228700
@JohnRennie At the time, it didn't seem such a hindrance but I now realise how much better this is.
 
user228700
@JohnRennie Ah, yes, I'd almost forgotten about the laptops! Cute? :-o Now I am concerned...
 
@Kaumudi.H It's so small but perfectly formed :-)
 
user228700
:-) OK. Well, I'll leave u to play with it then. BTW, the CD drive in this thing works fine. Turned out that the problem was indeed with the old drive, not the CDs themselves!
 
4:20 PM
Good. Have you watched any films on it?
 
@EmilioPisanty, you around?
 
user228700
Yes, just one oldy--bits and pieces of it.
 
I think my niece uses her laptop mostly for watching films on. I bought it for her schoolwork!!!
 
Hi, everybody.
 
o, nvm, found it.
 
4:22 PM
Hi
 
@DanielSank, hello
 
user228700
And it was great :-) The only problem is that I tilted the video on VLC but now I'm unable to get it to tilt back to 0/360 degrees. It's stuck at 1.
 
user228700
Hello :-)
 
@Kaumudi.H Your video is rotated by 1 degree?
 
user228700
Yep.
 
4:23 PM
Hello everyone

I have a question about waves in a rod:
Why is the formula based on Hook's elasticity modulus $\frac{F}{S} = -E \frac{\Delta l}{l}$
 
user228700
@JohnRennie Lol, I see :-P
 
negative on the right side?
This image proves how you can obtain the speed of a wave in a rod by using Newton's second law.
 
ah, i have the perfect idea for a community ad
=D
and thanks to bernardo and daniel I can use inkscape and not google drawings =D =D
 
Howdy
@heather Get Illustrator
 
@heather yup, what's up?
 
4:29 PM
Anybody? Sorry to disturb you @JohnRennie but I know that usually you are able to understand thing very quickly.
Any idea?
 
@EmilioPisanty sorry, i found what i was looking for...i remembered you waybacked that aerosol can question a while ago but forgot you posted it in chat.
 
user228700
@Sir: Yello :-)
 
I'll have a look ...
 
@heather hah
 
@SirCumference i'm torturing this poor chromebook enough already =/
 
4:30 PM
it's been deleted, I imagine
 
@EmilioPisanty the wayback, no, but the actual question, yes.
 
@heather Ouch, a chromebook? :/
 
user228700
Oh, @heather: Hello :-)
 
Not to sound condescending
 
@SirCumference yeah, remember, i've got linux and chromium running on it, and on the linux side texmaker, python 2 and python 3, a bunch of github repositories, etc, etc.
@Kaumudi.H hallo =)
 
user228700
4:31 PM
How's it going?
 
@Kaumudi.H good, how about for you?
 
@heather Wait, you know python? :O
I was 14 when I started learning programming languages...
 
Does anybody have an idea about my question? Which is about physics....
 
user228700
@heather Same here, sort of, thanks :-)
 
@trilolil it looks sensible to me.What's the problem?
 
4:32 PM
@SirCumference well, i don't know about "knowing" python, but i do have a small amount of experience with it, yes.
 
@heather yeah, figures.
The Wayback Machine has it at -6, though
 
@JohnRennie Why is it $-E \frac{...}{...}$ and not $E \frac{...}{...}$ ?
 
final score -11
 
Well still, I've only just gotten started using github. Makes my life easier.
 
github is pretty cool.
::shouts out thanks to Daniel Sank::
 
4:33 PM
Really helps me work on my userscripts
 
::and Bernardo::
 
@trilolil You start with $$F = ma = S\Delta p - S(\Delta p + \frac{\partial\Delta p}{\partial x}dx) $$ Yes?
 
@JohnRennie yes
 
And this simplifies to: $$ F = ma = - S\frac{\partial\Delta p}{\partial x}dx $$
 
yes
 
4:36 PM
@obe Quick question
 
Then substitute $$ ma = \rho S dx \frac{\partial^2D}{\partial dt^2} $$
 
@JohnRennie yes ok.
 
And you get $$ \rho S dx \frac{\partial^2D}{\partial dt^2} = - S\frac{\partial\Delta p}{\partial x}dx $$
 
yes
so actually they just transfered the minus sign to the other side of the equation?
It has nothing to do with Hookes law itself?
@JohnRennie
 
@heather :-D
 
4:41 PM
@trilolil well it starts with what is basically Hooke's Law $F \propto -dx$
 
@JohnRennie ok.
Hookes law calculates a force that is always oriented to the origin. (as far as I know)
I don't mean to be rude by any means. But I am affraid I didn't get the point you are/were trying to make.
@JohnRennie
 
@SirCumference You're doing it again: If you don't ask the question right there, then obe will find this ping in his inbox when he logs in and will have no idea how to respond, it's a notification that's completely useless.
 
^ And it's against intergalactic law.
3
 
^inter-multiversal law.
@SirCumference but...? (I have heard nothing condescending =P)
 
@EmilioPisanty It certainly looks refreshingly different from the usual layout! I feel something is off about it though, but I can't nail it down and it may just be "it's not the usual layout"...
 
4:56 PM
@heather o_O
@ACuriousMind I agree, it's a bit weird but I can't say why
 
Groan, the homework questions are piling up and I'm all out of downvotes :-(
 
@ACuriousMind It certainly beats Computer Modern.
 
obe
@SirCumference what?
 
@JohnRennie Do you really mean downvotes or rather close votes?
 
oops, yes, I did mean closevotes. Is there a limit on downvotes?
 
5:02 PM
@obe Can you send over the astronomy logo you used in your background?
 
obe
@SirCumference why?
 
I might use it for a community ad, if that's ok with you
 
@JohnRennie You have 40 up/downvotes (one counter for both) in a day, it's hard to hit that if you're not trying to
 
obe
can't I make the ad? :(
 
You want to?
 
obe
5:03 PM
yes
 
Didn't know, since you aren't on Astro
 
Can you undo in inkscape?
 
obe
@ACuriousMind do you see anything out of place in my profile image?
 
It looks blue as always ;)
 
obe
look carefully.
 
5:05 PM
There's some sort of creature in the center
 
obe
yeah it's a penguin xD
I didn't try to hide it, but you're the first person to notice it within a few seconds.
 
there's a penguin in there?
i honestly thought it was a bunch of frozen, blue machinery.
 
@obe I had to look at it separately, in the size at which it appears in your profile or here it's almost impossible to see
 
obe
yeah that's what I meant by "look carefully".
I showed it to my friend on my phone zoomed up all the way and he didn't notice it.
after like 5 minutes he saw it.
if I didn't put a shadow around it it would probably be even harder to see. lol
@ACuriousMind you changed your profile description :D
 
5:11 PM
ah, I see now.
 
It doesn't exactly stand out :-)
 
thank you, Sir Rennie.
 
@obe Slightly, yeah. I was changing the picture anyway
 
@EmilioPisanty, I'm sorry, but I hate inkscape.
=/
 
obe
@heather you should use adobe illustrator, it's really easy to use and a lot more powerful than inkscape.
it even has an option to turn a regular image into a vector you can use in a latex document.
so it doesn't pixelate.
 
5:13 PM
1. does it cost $
 
obe
I think for students it's $10 a month, idk if you can afford that.
 
Sadly yes, Illustrator is megabucks.
 
i have no megabucks.
i don't even have normal bucks.
 
obe
not even $10 every 30 days?
 
@obe Inkscape can do vector graphic too, that's no problem
 
obe
5:15 PM
@ACuriousMind can it turn say for example my profile image into a vector?
 
@obe for a single community ad!? I'm not paying $10 bucks period, let alone every 30 days.
 
@heather: what is so bad about InkScape? (I speak as one who has never used it)
 
obe
@heather oh you can get a 30 day free trial.
 
i don't create images every day, it wouldn't make sense to buy it.
 
obe
no payment information required.
 
5:15 PM
@obe hmm, might have to look into it then.
 
@obe No, it's meant to create vectorgraphics, not turn other images into them
 
obe
@ACuriousMind illustrator can do both though.
 
@JohnRennie well, I'm just frustrated because i didn't use it well (read: i was stupid) - i thought all i'd drawn was going to be in-frame and it wasn't and stuff. and it's just non-intuitive (compared to what i'm used to using).
 
obe
@ACuriousMind btw I've noticed that all latex vector graphics (diagrams or etc) look exactly the same in terms of style, is it because inkscape has presets or something?
 
I'm not sure what you mean (also, LaTeX can embed images other than vector graphics)
 
obe
5:18 PM
what I mean is that most people use inkscape to make vector graphics for their latex documents (I think), and most vector graphics people use look the same, so what's the deal?
i.e. same line thickness, same shapes, etc.
 
Yeah, that's probably because most don't fiddle with those presets unless they have a reason to
 
obe
so that's where inkscape is probably better than illustrator, since illustrator doesn't assume that you're going to be making latex graphics so it has too many customizations and not many presets.
so inkscape is probably faster for most purposes? (I think)
 
no idea, I never used illustrator and I used inkscape only when I needed to make some graphics which wasn't all that often
 
@obe The result wouldn't look nice, I'm afraid, unless your source bitmap is very high quality. With so much detail, the file would be quite large too.
 
obe
@JaimeGallego yea I tried it with low quality images and it makes the vector look like a smudged version of the original image.
and for large images it can take like 30 minutes to process even on a decent computer.
 
5:24 PM
I have a question about waves in a rod:
Why is this formula which is based on Hook's elasticity modulus negative: $\frac{F}{A} = -E \frac{\Delta l}{l}$ . In other words why is it -E and not +E ?
(cf 6th line)
 
@obe That's why designers avoid vectorizing.
They just do their work on Illustrator, then export it to bitmap if needed
 
@trilolil The force and the extension are vectors, and they point in opposite directions. If you stretch a spring, i.e. dx is positive, then the force points in the other direction so it's negative.
 
@JohnRennie Oh so it is just exaclty like Hooke's law?
Could E by any means be a negative value?
 
No the modulus is always positive.
 
Does that also apply to a fluid? $k = - \frac{1}{V} \frac{\Delta V}{\Delta p}$ i.imgur.com/15Gf5dc.png
I mean is that also just like Hookes law? @JohnRennie
 
5:38 PM
Yes. Strictly speaking it's not Hooke's law as that's for 1D systems.
 
@JohnRennie If striclty speaking it is not, what is it then?
 
Well the equivalent of the Hooke's law force constant is the bulk modulus
 
obe
@JohnRennie @BernardoMeurer I have a desktop and I want to upgrade its hard-drive to ssd, what do I do?
 
@obe Hello
@obe What's your budget?
 
Good move! An SSD will make it dramatically faster!
 
5:42 PM
It's very easy to do
 
obe
256 gb ssd I guess?
 
Well how much disk space do you need?
 
obe
idk how much they cost but a decent one I suppose.
I don't need much
 
@JohnRennie OK thank you very much for that explanation!
 
I like SanDisk SSDs because they're cheap, fast and reliable.
 
obe
5:43 PM
@JohnRennie yep :D
okay so how do I know if it's compatible?
 
A 256GB SanDisk is around £65 in the UK.
 
@obe Sandisk is a good pick for affordability
 
SSDs and ordinary SATA disks all all compatible.
 
Samsung and Intel have the best performance but are $$$
 
Any SSD will work in your PC.
 
5:44 PM
^ That, SATA3 FTW
 
obe
this is my pc dell.com/ca/business/p/optiplex-3020m-desktop/pd just for reference.
don't laugh btw, I got this for a specific reason.
 
That's a nice PC. They are tiny but fast!
 
obe
I wanted to take it around with me in my bag.
 
obe
5:45 PM
@JohnRennie well, was fast at least, 2-3 years ago
 
Amazon canada
 
obe
it's really slow now, idk if it's the hdd or what?
 
Any SSD will work fine in your PC.
 
obe
but I'm assuming ssd will make it faster?
 
5:46 PM
What version of Windows does it run?
 
The 480Gb is only 40 CAD more
 
obe
@JohnRennie ok great.
windows 10 pro
 
Probably a better investment
 
@obe If it has gotten slow, the first step is not to buy an SSD but to clean off all the crap that's accumulated over the years :P
 
obe
@BernardoMeurer ok, so do you recommend that?
ok
@ACuriousMind thing is, it hasn't accumulated any crap. I only have like 3 games on it and few important software.
and a bunch of (large) pdfs
 
5:47 PM
@obe I currently have a SanDisk 240GB SSD (Thanks John!) and It works great. I also have a 500GB HDD(Thanks John!) and the speed difference is REMARKABLE
 
@ACuriousMind experience tells me it's rare for that to help much.
 
obe
it's currently a 7200 rpm hdd.
when I first got it it was as fast as my ssd laptop but now it's slow.
weird.
 
@ACuriousMind Everyone should use an SSD, HDDs are crap for an OS to run off of
 
obe
@BernardoMeurer ok I'll buy one of those ssds, but how do I install it?
 
The amount of cycles your computer wastes waiting for a disk read is bizarre
 
obe
5:49 PM
do I just give it to a repair shop?
 
@obe Nope
 
Bung in an SSD and do a nice clean install of Windows 10. Ideally from a Microsoft DVD as that will give the cleanest install, but the Dell install DVDs are not too bad.
 
You do it yourself
Open your PC
 
obe
no idea how lmao
 
Find the current drive
It will have two cables
 
5:49 PM
What's the Dell tag number of your PC.
 
@BernardoMeurer I'm not saying "don't buy an SSD" (I have those in both my laptop and my desktop and would never go back to not having them), but if the thing is really "slow" now when it wasn't before that indicates some other problems.
 
a larger one (power) and a small one(data)
 
obe
@JohnRennie where do I find that?
 
The tag number will be written on the PC somewhere - usually on a small label.
 
obe
@BernardoMeurer I'll show you right now.
 
5:49 PM
unplug these, take the drive off, put the new one and replug them
 
obe
apparently it's reason easy to open.
 
@ACuriousMind Well, he uses Windows it's his own fault :P
 
@JohnRennie Really? I've "sped up" my friends' computers more than once by disabling all the useless stuff they had running in the background :P
 
@DanielSank, oh, how are the user awards going? Do you have winners in all the categories?
 
The Owners Manual will have step by step instructions for replacing the disk.
 
obe
5:56 PM
thanks!
 
Actually I've been toying with the idea of buying a 3020M just on the grounds that they're cute :-)
 
obe
well now there's the 3040M.
it looks cooler, I think.
@JohnRennie OH
does this mean that I can change the processor and the memory too?
didn't know
 
@obe you can change the memory, though there will be an upper limit that the PC supports. However going above 8GB probably isn't worth it unless you run big apps. My own PC has just 4GB and that's fine.
 
obe
also I'm dumb in regards to this but, where is the OS running from?
if I replace the hhd will I lose windows 10?
 
However changing the processor is more restricted. You can only use processors that the BIOS supports. Generally speaking it isn't worth trying to change the processor.
 
obe
6:00 PM
I bought windows 10 from the microsoft store as a download and I have it on my usb.
do I have to reinstall?
 
@obe Yes. Once you swap the disk you will need to install Windows from scratch.
 
obe
oh ok.
 
Obviously you will lose all the data so back it up first. Though the data is of course still on the old disk.
 
obe
I'll just leave it on the old disk.
Idc about it lol
@BernardoMeurer should I buy the sandisk one or this?
it has a lot of good reviews it seems.
 
@obe If you do have space for an HDD and an SSD, then go for it.
 
6:05 PM
@obe that's a good disk as well.
 
@obe Samsung makes extremely fast and reliable SSDs at a premium
@obe I'd go for the 480GB Sandisk though
 
@ACuriousMind fair enough. If you do manage to pin it down, give a shout.
 
obe
@BernardoMeurer I never exceeded 250gb on any computer before.
@JaimeGallego I don't but I don't really need the old disk except for memories and stuff. xD
 
@obe I only had 100GB in cross compilers alone :P
 
::Looks at full 1TB disk::
 
6:06 PM
@heather why do you feel you need to apologize?
 
Interestingly enough, I was also planning to upgrade my HDD for the first time.
 
@heather All graphics software packages have learning curves, and they're usually pretty steep.
 
@EmilioPisanty because I learned about inkscape through you.
 
Inkscape is, I think, the best compromise between power, usability, and open-sourcedness
 
obe
6:07 PM
@JaimeGallego is it because of performance issues?
 
Inkscape is a work of art
OPEN SOURCE SOFTWARE
 
@obe It is a bottleneck, yes.
 
@BernardoMeurer ... is not as nice and limitless as you'd hope.
 
@EmilioPisanty Yeah, well, FOSS can only go so far when competing with proprietary solutions
 
↑ that's the latest libreoffice running on the latest windows
 
6:09 PM
I have a love hate relationship with libre office
 
@EmilioPisanty LibreOffice is terrible.
 
@JaimeGallego I'm driving all the way to Spain and bitch slapping you
 
The last time I looked at LibreOffice I though it seemed very cluttered. Far from the simple plain UI I expected.
 
@JaimeGallego LibreOffice is a key bit of central infrastructure if people want to pretend that it is possible to build a FOSS system in full.
the UI above is bad by 2001 standards
it is indefensible post 2011
 
Libre Office is a piece of software no one wants to maintain, but that we all need. The UI is horrible, but it is usable, and the software does work well
The only proprietary thing on this machine are the Nvidia drivers
 
6:11 PM
@BernardoMeurer Don't worry, Stallman is already on the way with his katana.
 
obe
@JohnRennie my desktop keeps dropping wifi recently and the internet is really slow.
does that mean I should also replace the wifi card?
or will the ssd fix that too?
 
My favourite Office suite is Office 2003. It still runs and indeed I'm still using it every day. Every version of Office since has been slower and more cluttered with things I never use.
 
@JaimeGallego I met him a couple months ago :)
@obe Hm, I'd say try a fresh Windows install with your new drive and see if that helps
sounds like a driver issue
 
obe
uh oh, I forgot to ground myself before opening my computer.
is it dead now?
 
If not investing on a better wireless card could be a good idea
 
6:13 PM
@obe it's hard to say, but i'd be surprised if the wifi card was to blame as wifi cards are all pretty similar these days.
 
@obe I never ground myself, but I'm in humid weather
 
@obe no :-)
 
obe
I didn't touch the motherboard, just the plastic on the hdd.
 
I hate libre office. google drive and LaTeX serve all my document needs.
 
obe
should be safe right? the humidity here is like 50-70% i think.
 
6:14 PM
@heather This is why I love you
PREACH
 
I have never broken a PC due to static and I never use a grounding cable. I'm not saying it can't be done, but it isn't easy.
 
@BernardoMeurer i thought you just threatened to slap someone who disliked libre office...
 
obe
ok.
 
@heather Yes but you provided an awesome, also mostly FOSS solution to the problem :)
 
obe
I'm going to go buy the ssd from a computer store because I don't want to wait for shipping.
bye guys and thanks for the help! :D
 
6:15 PM
@JohnRennie Same
 
@obe have a good day obe
 
@obe Bye!
 
@BernardoMeurer fair enough. =)
 
@ChrisJohn Could you change your last name to "White" please?
5
@SirCumference :P
 
Dude I can answer all¹ your GR questions. You don't need Chris White!
------------------------------------
¹ this may not be strictly true
 
6:19 PM
i kind've want to meet this chris white guy...
if only i'd started talking in chat a few months earlier i would've met him.
 
@JohnRennie I don't care for GR! I want someone to talk about arbitrary precision arithmetic with! I want someone to shit on Boost with! I want someone to praise C and GMP!
 
@BernardoMeurer ::glares:: Python. Only Python.
 
I can code in C(++) ...
 
@heather Hm?
 
2 days until 0celo's back
 
6:20 PM
@JohnRennie C++ is nice, I use it more than C because I'm a lazy peasant
 
@BernardoMeurer joking response to "I want someone to praise C and GMP"
 
@heather Ah, lol
 
What's GMP
 
You're not old enough for C yet.
C comes with alcoholism and unprotected sex
 
Google tells me it's the Greater Manchester Police :-)
 
6:21 PM
@JohnRennie It's the dopest!
 
The GNU Multiple Precision Arithmetic Library (GMP) is a free library for arbitrary-precision arithmetic, operating on signed integers, rational numbers, and floating point numbers. There are no practical limits to the precision except the ones implied by the available memory in the machine GMP runs on (operand dimension limit is 232-1 bits on 32-bit machines and 237 bits on 64-bit machines). GMP has a rich set of functions, and the functions have a regular interface. The basic interface is for C but wrappers exist for other languages including Ada, C++, C#, Julia, OCaml, Perl, PHP, Python, R,...
^I think
 
@BernardoMeurer wat
 
It's what I used for my super ackermann implementation
 
very nice
 
6:22 PM
@BernardoMeurer look at all this C(++) code dude - all my own work
 
@JohnRennie Damn, sweet!
I never even touched anything with Win32API
 
@BernardoMeurer part timer!
 
the answer here is just that the space between the galaxies, not the galaxies themselves moved right?
 
@BernardoMeurer Tried to make a Visual C++ app once. Got to draw an ellipse before desisting.
MSDN is a nightmare.
 
@JaimeGallego The only visual thing I engage in is reading
 
6:28 PM
@JaimeGallego VC++ separates the men from the boys! :-)
 
I hate the MSVCC
That's one shit compiler
with a good dbg though
 
If the universe is currently infinite (which is possible) then it was always infinite.
Choose any distance you want, greater or less than the Hubble sphere, and there will be galaxies there.
 
I have programming next semester
I wonder how that class will go
 
@BernardoMeurer Just checked your GitHub. Impressive. I never seem to find time to do some programming.
I consider my time management to be... dubious
 
@JaimeGallego Thanks man :) Now at uni it's kind of hard to find time too, my kernel project has spider webs on it, but I'm going to do some work this week
@DanielSank Check hangouts
ATTENTION EVERYONE
I HAVE PASSED REAL ANALYSIS
6
 
6:49 PM
Congrats
 
@ACuriousMind @anonymous @DHMO @AnyoneIForgot Thanks for the help!
:)
 

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