# Search results for query: *

1. ### A How do Magnetic Gradiometers work?

I'm a bit of a layman when it comes to this sort of thing, but from the literature I've read, it looks like most gradiometers utilise two magnetometers. Much of my understanding stems from this paper: http://library.seg.org/doi/abs/10.1190/1.2164759 but from the fairly limited articles on...
2. ### A How do Magnetic Gradiometers work?

Whenever I've encountered measuring magnetic fields with magnetometers, they've typically been very large magnetic fields (up to a few T). Magnetic fields fall off rapidly with distance and so I generally figured that measuring weak fields at distances on the order of cm (let alone m) was very...
3. ### Dispersion relation for the free electron model

I'm trying to get my head around what this means exactly. I've plotted the graph to help verse me with the functions that I've derived. From the free electron model, the wavefunctions are treated as planewaves of the form \psi_\mathbf{k}(\mathbf{r}) = e^{i\mathbf{k}\cdot\mathbf{r}} Due to...
4. ### Drawing Feynman Diagrams

Yeah, okay, so I could use a photon or a Z for that interaction. So would it be accurate to say both diagrams would contribute to the probability amplitude?
5. ### Drawing Feynman Diagrams

Hey there, this isn't a homework / coursework question so I didn't think it should be posted in that section. I can't seem to find a source which explicitly tells you how to determine which bosons are used in reactions. I understand how to work out if a reaction is legal or not by using charge...
6. ### Cv as a function of temperature for ionic solid and metal

Would it be okay to bump this question? I have a similar question and I can't find these plots anywhere.
7. ### Finishing my Bsc in Physics & Computer Science, not sure what to do now.

Hello everyone. I'm a third year Physics and Computer science student (predicted a 1st class - studying in the UK) and I'd like some advice on what to do in the future. I apologise in advance if this OP turns into a wall of text but I have tried to do some research prior to this post. I feel...
8. ### Quick Braket notation question

Ah crud, I completely forgot that's how you write Expectation value. so, just to confirm I have a grip on this, \langle x \rangle = \langle \psi \vert {x} \vert \psi \rangle = \int_{-\infty}^{\infty} \psi^* x \psi dx Is that right? Assuming the limits are from infinity to minus infinity...
9. ### Quick Braket notation question

I'm a complete noob with Braket and I've only just started getting to grips with it. For completeness' sake though (from the book I'm currently reading), I can't seem to find a definition for: \langle J_z \rangle Would this just be the "magnitude" of J_z? Thanks
10. ### How do you get good at statistical physics?

Thank you for the reply. I'll give these a read over christmas and see how things go. I'll still check this thread to see if somebody else can contribute.
11. ### How do you get good at statistical physics?

Hello there, I'm a second year physics student who like most, has exams around the start of the next year and as such, have started revising for my exams. The term has introduced new physics I wasn't initially familiar with such as Quantum mechanics and advanced differential calculus. Another...
12. ### Is homework help plagiarism?

Yeah, I'll pay him a visit with the rules (which I've just printed) on Monday. Thanks for the words. I'd like to see this thread stay open just so I can see what other people have to say on this topic. Thanks.
13. ### Is homework help plagiarism?

Guess I'll have to ask him next time I see him. I suppose the rules being obeyed make sense though.
14. ### Is homework help plagiarism?

I usually find myself asking a question here if I get stuck on a question. Is this plagiarism?
15. ### Maxwell Boltzmann Distribution Question

Ok, so \bigg[{-e^{-\frac {mv^2}{kT}}\bigg]_0^t will give me \lim_{t \to \infty}({-e^{-\frac {mt^2}{kT}} + 1) yeah? Sorry if this is annoying, I've never actually done something like this which seems a bit strange considering a question requires it. I appreciate the help.
16. ### Maxwell Boltzmann Distribution Question

I thought so. This might seem stupid, but I really don't know how to evaluate the integral when one of the limits is \infty. Could you shed some light on that please?
17. ### Maxwell Boltzmann Distribution Question

ok, so you're saying N = \frac {Ckt}{2m} \bigg[{-e^{-\frac {mv^2}{kt}}\bigg]_0^\infty which yeah, makes sense. But do you want me to rearrange it to make C the subject while not evaluating the integral?
18. ### Maxwell Boltzmann Distribution Question

Hello everyone Homework Statement The equivalent of the Maxwell-Boltzman distribution for a two-dimensional gas is P(v) = Cv e^-\frac {mv^2}{kt} Determine C so that \int_0^\infty P(v)dv = N Homework Equations Not really sure The Attempt at a Solution I wasn't really sure how to tackle...
19. ### Rotational Energy Deriving

Thanks for the reply CompuChip, sorry for this late reply. I took onboard what you said, perhaps you could verify my answer. I have v = \omega r I = \int dV \rho r^{2} dm = \rho dV I = \int \dfrac {dm}{\rho} \rho r^{2} I = \int dm r^{2} I = r^{2} \int dm I = r^{2}m m = \dfrac...
20. ### Rotational Energy Deriving

Hello, I think I've got the right idea on how to perform this question but I just need a little bit of help. Homework Statement Show that for a rigid body rotating with angular velocity \omega the energy of rotation may be written as: E = \dfrac {1}{2}I\omega^{2} where the moment of...
21. ### Determining whether a matrix function is linear?

Ok, I think I understand, so if I take the first question and use the criteria f(cx) = cf(x). a) \begin{pmatrix} a & b\\ c & d\\ \end{pmatrix} \begin{pmatrix} x\\ y\\ \end{pmatrix} = \begin{pmatrix} x - y \\ x\\ \end{pmatrix} I get \begin{pmatrix} ax + by\\ cx + dy\\ \end{pmatrix}...
22. ### Determining whether a matrix function is linear?

Homework Statement Which of the following functions is linear? Give reasons if they are not linear. If they are linear, give the corresponding matrix. Homework Equations a) R \begin{pmatrix} x\\ y\\ \end{pmatrix} = \begin{pmatrix} x - y \\ x\\ \end{pmatrix} b)...
23. ### Satellite Slingshot manoeuvre question

an unfortunate bump :(
24. ### Satellite Slingshot manoeuvre question

I've already attempted to work everything out by the way but my answers seem a little off. Homework Statement A satellite performs a sling shot manoeuvre around a planet. The mass of the planet is 6.00 * 10^{24} kg and the mass of the satellite is 7.00 * 10^{2} kg. The satellite approaches...
25. ### A regular expression and a Windows permission (cacls) question

Hello, firstly, what does the regular expression "\\+" do? Would that literally match up "\+". Could I possibly get some recommendations on some software to try regular expressions with as well actually please? and secondly, I've been fiddling around with the cacls command and I've noticed...
26. ### Solving Ideal Gas Q: Temps & Press at A,B,C,D

So basically, if I can find out what K is from the Adiabatic condition, then I should be able to calculate the values of P and V for the other points? Except I don't have a point which has both P and V values.
27. ### Solving Ideal Gas Q: Temps & Press at A,B,C,D

Homework Statement 1) Consider one-mole of gas in a heat engine undergoing the Otto Cycle a) The gas absorbs heat, at constant volume between 120'C and 300'C b) The gas expands adiabatically from V1 to V2 = 5V1 c) The gas cools, at constant volume to Td at point D where the pressure is 1At d)...
28. ### Vector equation questions

Thankyou both very much for the help Yeah, I completely understand where my problem is, I'll definitely do this. Thanks again.
29. ### Vector equation questions

ah, I see the error of my ways, ok: OP(t) = OA + (t)(BA) = (1-t)OA + (t)OB (1-t)OA = (5 -5t, 0, 1-t) (t)OB = (7t, 4t, 7t) OP(t) = (5 -5t, 0, 1-t) + (7t, 4t, 7t) OP(t) = (5 + 2t, 4t, 1 + 6t) So that's the answer? I think I'll have to do more research on this regardless?
30. ### Vector equation questions

Ok, well, I'm really not sure what I'm doing but I did this: OP(t) = OA + (t)(BA) = (1-t)OA + (t)OB (1-t)(5,0,1) + (t)(7,4,7) (-6t + 6) + (7t + 4t + 7t) 12t + 6 OP(t) = 12t + 6 Surely there's more to it then that?
31. ### Vector equation questions

Thanks a lot Yeah, just got back, I'll take a stab at this now and post my result :)
32. ### Vector equation questions

I was hoping I could be linked to some resources to find the answer actually. Equation of a plane takes the form of Ax + By + Cz + D = 0 Point = (1, 0, 1) Normal point = (i + j - k) = (1, 1, -1) Point Normal Form = (1, 1, -1) x ((x, y, z) - (1, 0, 1) = 1(x -1) + 1(y-0) -1(z-1) = x...
33. ### Vector equation questions

Hello guys, I've got two questions here which I'm really unsure about on how to actually tackle. As a result, maybe it would be better if I could possibly be linked to some resources where I could read up on how to actually solve them. Homework Statement 1. Find the equation of the plane in 3...
34. ### Simple complex number question

Homework Statement 3. Write down the (x+iy) form for the complex numbers with the following modulus and argument (in radians): (a) Modulus 1, argument pi (b) Modulus 3, argument -pi/3 (c)Modulus 7, argument -4 Homework Equations Modulus = ((a)^2 + (b)^2)^1/2 Arg = the angle...
35. ### Gravitational Fields question

ah cool, ok, thanks for the help everyone.
36. ### Gravitational Fields question

god damn it. Ok. Weight at sea level = 980N weight at summit = mg g = 6.67*10^-11 * 6.0 * 10^24 / 6410,000² g = 9.74 100 * 9.74 = 974 980 - 974 = 6N so the difference in weight is 6N? Is that correct? Can't believe my entire mistake was using the wrong mass.
37. ### Gravitational Fields question

g = GM/r² gr²/M = G 9.8 * 6400,000² / 100 = G G = 4.01408*10^12 gr² / G = M 9.8 * (6400,000 + 10,000)² / 4.01408*10^12 = M M = 100.313 Weight = Mg 983.06 - 980 = 3.06N So the difference in weight is 3.06N? The only problem is that she gained weight at the summit, she didn't lose it. So...
38. ### Gravitational Fields question

Ok, so at sea level, the lady weighs 100*9.8 = 980N so I need to find the value for g at the summit of the mountain. I'm still confused with this constant business though, on wikipedia, it says the units of G are N(m/kg)². So do i need to square the mass? g = GM/r² g = 6.67*10^-11 * 100² /...
39. ### Gravitational Fields question

thanks for the reply. But actually, I think you've lost me even more :)
40. ### Gravitational Fields question

[SOLVED] Gravitational Fields question Homework Statement 1. Mount Everest is approximately 10 km high. how much less would a mountaineer of mass 100kg (including backpack) weigh at its summit, compared to her weight at sea level? Would this difference be measureable with bathroom scales...
41. ### Circle equation question

Thanks for the replies, I managed to reach sqr29 using a different method though. x² + y² - 8x - 4y = 9 so x² + y² - 8x - 4y - 9 = 0 and the equation of a circle is (x - a)² + (x - b)² = r² expand out x² + y² - 2ax - 2by + a² + b² - r² equating coeficients -2a = -8 a = 4 -2b = -4 b =...
42. ### Circle equation question

oops, fix'd (i hope :) )
43. ### Circle equation question

Homework Statement A circle has equation x² + y² - 8x - 4y = 9 (i) Show that the centre of this circle is (4,2) and find the radius of the circle. Homework Equations Circle equation = (x-a)² + (x-b)² = r² The Attempt at a Solution Well, if the centre of the circle is (4,2). Then the...
44. ### Solving Fish Refraction Problem Using Law of Refraction

Think about it, what is a perfectly flat surface of water with no waves a metaphoric equivalent to?
45. ### Momentum of a snooker ball

argh! you're kidding me? I've been stuck on this question for almost 30 minutes and it's that simple!? I thought it deflects off the side at a right angle :P I get the right answer now, thankyou!
46. ### Momentum of a snooker ball

Homework Statement A snooker ball of mass 0.350kg hits the side of a snooker table at right angles, and bounces off also at right angles. If its speed before collision is 2.8ms^-1 and its speed after is 2.5ms^-1, calculate the change in its momentum. (The answer to the question is not 0.105kg...
47. ### Expansion of exponentials (very easy)

aha, thanks for the help. Just got a bit confused with the powers for a moment it seems.
48. ### Expansion of exponentials (very easy)

Yeah, i tried using foil. Foil if I'm not mistaken would grant me. (e^x + e^-x) (e^x + e^-x) (e^x * e^x) + (e^x * e^-x) + (e^-x * e^x) + (e^-x * e^-x) (e^2x) + (1) + (1) + (e^-2x) (e^2x) + (2) + (e^-2x) Is that right?
49. ### Expansion of exponentials (very easy)

Sorry, the +2. I can reach the e^2x + e^-2x but I can't reach the "+2" which means the method I'm using is incorrect. I haven't touched this stuff in a while so I'm just trying to re-remember it.
50. ### Expansion of exponentials (very easy)

Sorry, I'm having a severe mental block here, sorry if this is laughable. Question Expand (e^x + e^-x)^2 I've got the answer but I'm just stumped at how to reach it, I don't know where the 2 comes from: Answer e^2x + 2 + e^-2x Thanks (and sorry again)