## Search found 23 matches

Sun Oct 25, 2009 10:32 am UTC
Forum: Science
Topic: Weiss theory of ferromagnetism
Replies: 2
Views: 2380

### Weiss theory of ferromagnetism

Okay, Weiss theory can be used to predict the heat capacity relating to ordering of electron spin, it does alright but has 2 major flaws. The first of these is that (after Curie temp) the heat capacity component should drop straight to zero, but IRL there is a decaying tail of magnetism. This is due...
Sat Oct 17, 2009 11:08 am UTC
Forum: Computer Science
Topic: Excel needs to sod off and die
Replies: 13
Views: 3684

### Re: Excel needs to sod off and die

Solved Problem: The default display of the equation (as seen in Masher's post) leads to horrible rounding errors. Need to right click equation and change the display to many sig fig and then the equation works.... eejit machine. In answer to why I'm doing this - as said in first post I need to conve...
Fri Oct 16, 2009 7:33 am UTC
Forum: Computer Science
Topic: Excel needs to sod off and die
Replies: 13
Views: 3684

### Re: Excel needs to sod off and die

Interesting, the polynomial you've got is subtly different to mine.... given the magnitude of the power terms that might make a massive difference (seriously, for x =100, looks good on the graph; but the displayed eqt gave the answer of -2000ish when pasted into the spreadsheet. Was not pleased) Che...
Thu Oct 15, 2009 11:20 pm UTC
Forum: Computer Science
Topic: Excel needs to sod off and die
Replies: 13
Views: 3684

### Excel needs to sod off and die

I needed to extrapolate intermediate values for some collected data, so I graphed it in Excel (scatter graph) and fitted a 6th order Polynomial to the data (damn good fit) I planned to nick the equation for the polynomial to predict values between my data points... Problem is that it doesn't work, t...
Fri Oct 09, 2009 11:24 am UTC
Forum: Science
Topic: Intricate conservation issues in relation to Doppler shifts
Replies: 4
Views: 1040

### Re: Intricate conservation issues in relation to Doppler shifts

CMB temp goes down because the universe expanded. Same amount of energy, just diluted now. That much is relatively clear but it doesn't offer a mechanism. The CMB is "fossil" photons - yet they have managed to change wavelength, why this has happened was the tricky part. Regarding redshif...
Tue Sep 22, 2009 5:02 pm UTC
Forum: Science
Topic: Eight billion years from now
Replies: 30
Views: 2427

### Re: Eight billion years from now

8 billion years is twice as long as the planet has been around to date, nothing will be recognizable, ..... Sources: Wikipedia This cool FAQ from NASA: http://helios.gsfc.nasa.gov/qa_earth.html 'Death From the Skies!' by Phil Plait Ph.D, AKA The Bad Astronomer This post is full of win, pretty much ...
Tue Sep 22, 2009 4:51 pm UTC
Forum: Science
Topic: Intricate conservation issues in relation to Doppler shifts
Replies: 4
Views: 1040

### Intricate conservation issues in relation to Doppler shifts

When explaining life, the universe and everything scientific to an interested but more arts minded friend I discovered my meandering explanation set up a question that I couldn't answer... So here it comes with some background. 1) Question that is fine: A star whizzing through the universe (relative...
Mon Sep 21, 2009 11:13 am UTC
Forum: Hardware
Topic: Laptop Batteries
Replies: 4
Views: 979

### Re: Laptop Batteries

In clarification, My battery failed circa the 1year mark. Hence not soon enough to come in under battery warranty, but my computer as a whole is still under warranty. Also meaning the battery has a bad lifetime but not an appalling one (well, it was appalling in terms of hours that I've used it - bu...
Mon Sep 21, 2009 12:05 am UTC
Forum: Hardware
Topic: Laptop Batteries
Replies: 4
Views: 979

### Laptop Batteries

NB: I'm in the UK My Vaio battery recently went to shit (10 min runtime from fully charged) which rather annoyed me, due to the fact that I'd barely used the damn thing [At Uni, the laptop lives plugged into the wall and the battery lives 10 feet away in a drawer]. First question: Sony are feeding m...
Fri Aug 14, 2009 12:12 am UTC
Forum: Mathematics
Topic: Help me integrate this!
Replies: 10
Views: 1466

### Re: I'm being retarded - Help!

Ack, show your work man. When you say, "Do parts and fiddle second term into recognition form," that's like five steps right there. Why must I guess what parts you are using when you integrate by parts? Ah jeez, I SO deserved that slap on the wrist. The error was in my parts selection. &q...
Thu Aug 13, 2009 4:11 pm UTC
Forum: Mathematics
Topic: Help me integrate this!
Replies: 10
Views: 1466

### Re: I'm being retarded - Help!

integrate \int x^3e^{bx^2} Do parts and fiddle second term into recognition form = -x^2e^{bx^2}/{2b} + \int(2bxe^{bx^2}){3/{4b^2}} Final Ans = - ({x^2/{2b} +{3/{4b^2}}})e^{bx^2} Just some trivial maths from my Quantum course (first step in a Heisenburg proof) but it's just not my day...
Thu Aug 13, 2009 3:37 pm UTC
Forum: Mathematics
Topic: Help me integrate this!
Replies: 10
Views: 1466

### Help me integrate this!

Very quick problem. integrate x^3e^{-bx^2} Preview is suggesting the forum imath won't show correctly, this is the sum: http://integrals.wolfram.com/index.jsp?expr=A(x^3e^({bx^2})&random=false Obviously I go for integration by parts and then rearrange my second term to get something I can do by ...
Sat Feb 14, 2009 8:27 pm UTC
Forum: Science
Topic: Dropping two balls.
Replies: 10
Views: 1527

### Re: Dropping two balls.

So a stack of 7 such balls has the top one reaching escape velocity. Seems a tad dramatic. There are 3 potential error sources extending the model to such limits. 1) Balls would stop behaving elastically in such high energy limits (in addition to air resistance and other "big KE" effects ...
Fri Feb 13, 2009 8:32 pm UTC
Forum: Science
Topic: Dropping two balls.
Replies: 10
Views: 1527

### Re: Dropping two balls.

Heya, In the blurb below I've put inverted commas "" around the technical terms that get taught in school at some point - no worries if you haven't come across them yet. 1)The answer is that the smaller ball bounces back to "9h" maximum, and it does so in the limit where the lowe...
Fri Feb 06, 2009 4:18 pm UTC
Topic: 0540: "Base System"
Replies: 220
Views: 69451

### Re: "Base System" discussion

I must confess, this comic confused me intensely... Because the base system referenced by everyone I know runs as follows 1: Kiss 2: Manual 3: Oral 4: Sex Home Run: Going straight to teh sexytime in one night. A euphemism for those who have a very successful pull at a party. 5th base: Optional termi...
Sat Dec 27, 2008 8:59 pm UTC
Topic: Human "breeding", and its implications
Replies: 95
Views: 12618

### Re: Human "breeding", and its implications

This thread looks like it might go the way of "aeroplane on the treadmill" type discussions (ie. We need to agree on facts before everyone gets angry that the other groups present have got all their basic assumptions wrong). 1) I think it's safe to say that, in an industrialised society, t...
Sun Oct 19, 2008 4:35 pm UTC
Forum: Science
Topic: Science books
Replies: 11
Views: 2041

### Re: Science books

The Feynman stuff is excellent for the broad understanding (which I'm guessing mean all is groovy for you) but in terms of their actual physics they do a fair bit of the equations in non-SI units, which a bit of a pain. The best book on Science (in the popular science style) I have ever read is &quo...
Sun Oct 19, 2008 4:15 pm UTC
Forum: Science
Topic: Potential energy of 2 dipoles
Replies: 3
Views: 2575

### Re: Potential energy of 2 dipoles

Thankyou for helping. Going through what you said 1) The potential energy comes from rotating the dipole (would apply in any field) but also translational because each dipole produces a non-uniform field [perhaps a part of the question is to approximate that the field is uniform at the dipole scale....
Sat Oct 18, 2008 6:15 pm UTC
Forum: Science
Topic: Potential energy of 2 dipoles
Replies: 3
Views: 2575

### Potential energy of 2 dipoles

Firstly, yes, this is a problem from my Uni degree that is giving me a bit of a brainfuck . However, answering the thing is in no way connected to my grades. I hope asking this question is not prize twatish http://forums.xkcd.com/viewtopic.php?f=18&t=4734 Problem: 2 dipoles of equal dipole momen...
Mon Sep 08, 2008 8:28 pm UTC
Topic: 0473: "Still Raw"
Replies: 238
Views: 40982

### Re: "Still Raw" Discussion

I'm convinced this is a private joke by Randall to induce nuclear war in the forum thread... Talking of which, I think post 13# is one of the subtlest pieces of "baiting" trolling I've ever seen I'm convinced that everyone (fine, 99%, I'm sure some that have no idea what's going on say it ...
Tue Aug 26, 2008 4:59 pm UTC
Topic: 0467: "X Girls Y Cups"
Replies: 217
Views: 62755

### Re: X Girls Y Cups Discussion

What REALLY confuses me about this comic is the following: (Search using google.co.uk, Web mode because images.... well you can figure it out yourselves - or look if you're particularly curious/brave) 2 girls 1 cup = 1,900,000 2 girls 1 cups = 2,200,000 7 girls 3 cups = 430,000 7 girls 3 cup = 8,500...
Thu Aug 07, 2008 10:12 am UTC
Topic: Creationism
Replies: 914
Views: 91314

### Re: Creationism

A very important point for those who want to talk about "Gaps in evolution". We look at long-term evolution by investigating the fossil record. Now, fossilising ANYTHING is really fucking hard work - the vast majority of animals are not fossilised when they die, being fossilised is in fact...
Wed Aug 06, 2008 9:15 pm UTC