# Search results

1. ### Combining Errors

Out of interest can that be used for any means of combinational error ? I.e. f = (d2 - d1) / (d2 + d1) Can I just take derivatives and then use the chain rule, or because d2 and d1 have the same error it can be done differantly ?
2. ### Combining Errors

Oops, sorry about the lack of thanks here! I read it ages ago, use dit then must have forgotten! :S Thank you for the help :)
3. ### Combining Errors

I didn't really know on the forum to put this, it isn't really homework or coursework, but it is a very small part of a project I am doing for uni, so essentially it could be worth marks so here it is, anyway... Homework Statement Im rubbish at combining errors and was wondering if someone...
4. ### Integrating a logarithm

Hello So I have a problem, which is to use integration by parts to integrate... \int^{1}_{0}(1-x) ln (1-x) dx The way I have been working is it to separate it out into just... \int^{1}_{0}ln (1-x) dx - \int^{1}_{0}x ln (1-x) dx and then integrating by parts on each of these...
5. ### A hamiltonial question

Yeah, I was basically just being rubbish at maths/not thinking about it properly.
6. ### A hamiltonial question

Aye I did thanks! :) Great, thank you all for your help!
7. ### A hamiltonial question

Yes that's correct :) Sorry, I have difficulty explaining things I don't understand very well, but I am getting there. The point of these seems to be that if you can conjugate the example and get back to your origonal statement then your statement is Hermitian (or at least this is the point...
8. ### A hamiltonial question

oh i see, so... (\hat{O} + \hat{O}^{\dagger}) ^{\dagger} = \hat{O}^{\dagger} + \hat{O}^{\dagger}^{\dagger} = \hat{O} + \hat{O}^{\dagger} thus proving it is hermitian. Ok, so, in a similar vein... \hat{O}\hat{O}^{\dagger} = (\hat{O}\hat{O}^{\dagger}) ^{\dagger} =...
9. ### A hamiltonial question

Sorry, I think I meant Hermitian operators. Thank you for the replies but it doesn't help me very much but I think that's maybe because I am asking hthe question wrong! :S What I am asking is how I would recognise the answer as a Hermitian in particular? Is it hermitian because...
10. ### A hamiltonial question

So I am working up to some exams and have a question regarding properties of hermitians, specifically the properties of Hamiltonian operators and trying to prove that for example if.. \hat{O} is a hamiltonian operator then... \hat{O} + \hat{O}\dagger is hermitian*. Now what I think I am...
11. ### Potential Steps

ok, scratch that last post - I've been re-reading lecture notes and think I've got a greater understanding - though the "eigenfunctions" are still eluding me. I know what they ARE, just not really if I have foundthem... First I separated the equation into the regions defined (x>0 and x<0) then...
12. ### Potential Steps

if I do this in the conventional way (rearrange into an equation with a y'' a y' and a y and come up with two roots of the form... alpha(1,2) = ± m((4*h(bar)^2*[v(x) - E])/2m) / h(bar)^2 I have read some examples which seem to suggest a better way of going about this is to let phi = A*e^ikx -...
13. ### Potential Steps

First it asks a few questions about what if it were a classical particle approaching the barrier. Much of this I understand and am OK with. Then we start treating the particle as a quantum thing so its governed by the TI Schrodinger EQ. So, what it wants me to do which I am a bit unsure about...
14. ### Line Integrals - Cartesian and Parametric

Im scared how all through my life everybody knows me and I know nobody... Maybe I am the guy from the truman show *shifty eyes* Also, it seems /everybody/ who takes it will be there! :S Evil maths for the lose.
15. ### Line Integrals - Cartesian and Parametric

just a few bits I don't understand still, bear with me if you will :) the first bit you say we need to get the intergral(9t^2), but I could have done that right from the start, AFTER saying B(r) = this and r = that. You later go on to say "The integral of F on a path r is the dot product F.R" -...
16. ### Line Integrals - Cartesian and Parametric

Hello Im working on some line integral problems at the moment. The first one is really only a check - I think I've worked it out... Compute the line integral of the vector field B(r) = x^2 e(sub 1) + y^2 e(sub 2) along a straight line from the origin to the point e(sub 1) + 2 e(sub 2) + 4...
17. ### Central Forces Questions

Wow, that was a very detailed answer, I was only looking for a pointer in the right direction but thanks :) It'll take me a while to wade through it all but I had a few questions to the previous posters first as a responce! (oh, it was all you! jeepers!)... h - I am really looking for the...
18. ### Central Forces Questions

Hello Im currently working my way back through a few past papers to ready myself for the new physics year, and was wondering if anybody could help me with a few puzzling questions that have me and my lecture notes stumped! I have created a image file with my questions and how far I have got...
19. ### Probability and Statistics

Hiya, this is second year UG Coursework (worth very little) so I don't want any "answers" to the questions (else its plagarism ;)) but hints in the right direction if you will :) Question 1 A random walker takes one step to the right with probability p times that with which she takes p...
20. ### Superstrings and the Laws of Physics!

ok, so maybe it is a bit "stupid", but if theere is indeed a place with no matter. No atoms, no neutrinos, no strings even, do the laws of physics apply there ? if there's nothing there, could laws be maintained ? i thought the point was that I am not neccessarily listening to what this guy...
21. ### Computer evolution

you say that we arent evolving, but it depends upon how you would determine, evolution. Is the discovery of new science evolution? or is it only evolution if its a physical change? Do we count as evolved if we erradicate war and feed the world, or are we only evolved when we get that vital...
22. ### Next 50 years is bleak.

tabloid, you have been watching far too much star trek. You may be correct as to the money thing, we may get some kind of card with all details on and is accepted anywhere, but books won't go. I love book, and lots of people do. Computer screens seem so much harder to read from than books do...
23. ### Superstrings and the Laws of Physics!

Im by no means an expert on any quantum phemonina, but here goes! I believe the law's of physics must be dictated by something, a physical quantity if you will. Like laws are enforced upon earth, only in a much better manner! If the smallest possible thing is one of these "superstrings"...

i had what felt like a mind control experience the other day, it really was quite strange. What happened was i woke up with a completele dead arm ( i probalbly slept on it), but i couldn't feel it atall, i felt like my arm was in another place completele! physically i couldn't move my fingers...
25. ### Feasability of an Ion Engine For Manned Missions?

hmmmmm, thanks fr the detail of the answer, but i wonder if i could extract a little more from you :P You say its physicsally impossible to use Ions to use this engine to break free from Earth's atmposphere, is this because Earth's atmosphere is full of stuff ? or because its so close to the...
26. ### Feasability of an Ion Engine For Manned Missions?

ION Drives are relatively new technologys, and have been used for small un-manned missions to comets and stuff, however, there incredibly weak (0.2N thrust from what i have read). Does this teachnology have the potential to accelerate something like a 5 tonne manned ship at 10m/s ? I have...
27. ### Mince Pie Fusion

if you dpont know an answer then just don't post! if i wanted non related answers i would have put them in the "nobody really wants an answer but uselss replys" forum. I want a theoretical solution to this problem. Maybe if you say its a car and a person doing the same journey (and wyes, the...
28. ### Palace 'ghost' caught on camera

he swings it open just after the camera has taken the shot then steps backa little bit. Or fishing line as he said, but i don't reckon they were that sophisticated. AND From the Beeb :P I am pretty surprised all the British TVs and Newspapers are actually buying into this. Its amongst the...
29. ### Palace 'ghost' caught on camera

that animated gif reveals it all for me. I mean eveidence from that... - it would like you to think the doors swung open where as there is a clear gap between when the doors are full yopen and when the doors are closed, thus easily giving time for someone to swing them open then get back...
30. ### Mince Pie Fusion

right, look. I am actually looking for serious answers now, Andthensome, i don't want sometign which would result in santa being blown up, that's just stupid. Njorl, that's a good idea (with the anti-mince pies) however, its a bit too much energy. I want it like you have a fuel tank, and you put...
31. ### Mince Pie Fusion

everythign i eat is used to power my body, the sled is the body i need to power :)
32. ### Palace 'ghost' caught on camera

I have several reservations about this! - ghost stories, generally tell of a ghost walking on the height or level that it would once have been on doing things that generally they would have done back in the day. Like walking around with a candle or whatnot. Now I am unclear of fire...
33. ### Telekinesis is it possible?

maybe telekenesis is just a subject which has not yet been uncovered due to the evolution of the human body not being able to "refine it" yet. Technically its possible surely. Sound is a force, it travels as waves, and can be heard from all drirections by your ears, because they are rigged to...
34. ### Mince Pie Fusion

Could anybody give me any suggestions, as to how i could convert 1 mince pie into around about 70 000J of energy, which could be used to power an engine of some sort ? I ask this, as I am creating a santa statistic :P not very origonal anymore i grant you, however, i was hoping to create a...
35. ### Future Small Arms

You can't make anything recoiless, you can only damp the recoil so it feels like its recoiless. [thinking out loud] As for the amount of rails. You could use nanotubes, there conductivity is amazing, there incredibly strong AND teher very very small. I don't know much about railgun physics...
36. ### Compressing Air.

Im currently drawing up plans for an air propelled chair (which ill probly never make :P). I was intending to pureply use air from the atmosphere, use some sort of compressor, to compress it, then send it flying out the back in order to displace the chair. However. I don't know if there are such...
37. ### Centripetal force and Acceleration

while in a centrefuge i believe the circle is not great enough to become a significant sickness worry. Like you psin on the Earth but don't get sick :) o(only obviously on a much smaller scale). And besides if your traveling at 5-6G, you aint ognna have enough force to project anything :P
38. ### Warping space

ohh i see, like the sun and planets on a net model. The heavier the object the more the net (or spacetime) bends (or warps!)! :) Thanks a lot :)
39. ### Carbon Nanotubes

oh i see, so when they say they use it in practical applications, they actually mean a whole load of carbon nanotubes all wrapped around one another! thanks :)
40. ### Warping space

it is saidf that if you have a mass large enough, the gravity created by that mass is enough to warp space. Now people are saying that due to quantum mechanics the warping of space is viable, within a spacecraft for example. Does this require the spaceship to have some sorty of gravity...
41. ### Nanotechnology? what gives?

the amount of reserach put into nanotechnology is increasing. Is it set to be the biggest scientific industry by about the yr 2010 with a whopping 1 trillian dollar research budget worldwide. The implementations are such... carbon nanotubes are "meant" to be extremele strong (see my thread in...
42. ### Carbon Nanotubes

I don't know if this is in the right forum but it seemed to fit quite nicely in here :P I was wondering about cxarbon nanotubes. There said to be really very strong, but what i don't underdtand is why? There so very thin! Doesd nanotechnology behave differasntly to microtechnology due to the...
43. ### Standerising NaOH

I am doing my chemistry practicle and my tecaher has told me that I need to standerise my 0.1moldm-3 solution of NaOH with HCl acid. But I don't know why or how, or what concentration of HCl. Does anyone have any ideas pls?
44. ### Walking through walls?

the timing needed to perform such a stuntwou dhave to be incredibly precise if my hypothesis is correct :)
45. ### To Beam Or Not To Beam?

t doesn't alwAYS mean the origonal will be destroyed, just changed and putback together :) just think of it as a more economical way of putting somebody in a car and driving them somewhere, only the car is (insert what the car is here) and you are energy. the cars speed limit is C, and powers...
46. ### Walking through walls?

A few months ago my physics teacher was talkign about "wave variance", and how everything has it, including walls and the human body. And that technically if the phasing was exactly the same (the wall and the human) then technically you could walk through the wall. I waswondering if there...
47. ### Represent the concept of Time best?

i have no physics real background to suggest this but ideas i hear, but i agree with neither :) i tihnk time is a straight track which you can turn around on and go back. like stephen hawking suggested in a brief history of time (?). Being an optomist i want to believe that's possible, and i...
48. ### To Beam Or Not To Beam?

hmmmm, i don't quite understand how them light years pertain to data! elaborate a bit! if you will :) as for making a clone of yourself i don't think its a great idea, in fact its just bad, because in the end someonehas to die or there's 2 of you! which isn't good! "beaming" people also seems...
49. ### DNA computer unbeaten at tic tac toe: Nature.com

thats not the point, the point is that its a computer made from DNA which has shown obvious intelligence, its the potential shown that matters :) This must be a great sort of breakthrough, because (from what i know of DNA computers), although DNAis slow at doing things, it can work out huge...
50. ### Going to Alpha Centauri

and the simple wondering of how they would get back :) maybe if the laser was rigged to the starship itself it may work. and does the laser have to stay on ?