Relationship Definition and 999 Threads

Hi, It has been a long time since I have worked with pdfs so perhaps someone can help. According to Wikipedia (http://en.wikipedia.org/w/index.php?title=Chi-squared_distribution#Additivity) the pdf of the addition of n independend Chi_squared distributed R.V.s is also Chi_squared distributed...

Hello everyone, I am currently reading the pages from a book called Thermal Physics, which was written by Daniel Schroeder; the pages to which I refer are 10-13. In these pages, he derives the relationship \bar{T} = kT. Here is one line that intrigues me, "So if this model is accurate...

It would be greatly appreciated if someone could help me solve this problem. There are two objects, let's call them object A and object B. Assume that object B is the Earth and object A is some other planet. If object A has 10 times the gravity of object B (Earth) and assuming object A and...

I don't understand why as temperature increases, the hall voltage goes down. What's going on with the electrons at increasing temperature to cause that to happen? And why at a certain temperature, the hall voltage starts to go back up? It's hard to find an answer on Google that gives me a...

HI, please help me... I am thirsty for any insights to my problem. I have a motor: Output: 60W VOLT:12V DC AMP: 7.5A RPM:1800 TORQUE: 3.5kgcm I have a motor reducer: for converting rotation movement of motor to up and down motion(for lifting heavy load) look like this...

Is there a hard and fast relationship between uncertainty and entanglement? In other words, if you have one phenomena, you have to have the other. I would think so because of the following example, but I wanted to make sure I understood the relationship. Please let me know if there are better...

I understand that generally, power and light bulb brightness are directly proportional. However, because there are so many ways to write the power formula (P=IV = I^2 * R = V^2 / R), I was a bit confused about what factors actually determine power and wanted to confirm whether the following is...

Hi all, I'm new here. I am curious to know if I could simulate high velocity on an object by applying the forces (compression) to it that it would experience at those high velocities. Also, I'm curious to know if this high velocity (Kinetic Energy) would generate heat, and if so, what's the...

Hi guys, this is my first post. I was just wondering what the exact relationship between current and voltage is. Transformers work on the basis that P = IV so by increasing the voltage, they decrease the current and less thermal energy is lost etc... We can test this out by making V the...

*to moderators: i apologize about the double post, but i didn't know how to get rid of the other post and i wanted a get an answer asap and no one was answering the other post so i reposted here in the appropriate section* enthalpy is the energy available if a system with some defined volume...

***i just realized that i posted this in the wrong section; could a moderator perhaps move this thread to the classical physics section please? Sorry for the trouble*** enthalpy is the energy available if a system with some defined volume were to be annihilated and have the atmosphere...

I has read the link http://physics.stackexchange.com/questions/75411/frequency-of-small-oscillation-of-particle-under-gravity-constrained-to-move-in and, i don't unsderstand why the integral \int^1_0 \frac{dy}{\sqrt{1+y^4}} is proportional to \Gamma (5/4) / \Gamma (3/4) . I had read the...

Why when the particles are nonlocalized, the single particle partition function is directly proportional to V, namely the volume of the system, and when the particles are localized, the single particle partition function is independent of V? (Pathria, Statistical Mechanics, chapter 4, section...

I know that magnetism can be explained as the relativistic interaction between say a current, and a moving charge. My question however is twofold, is magnetism nothing but electric forces when relativity is taken into account? If the answer is yes, does that make magnetism a sort of psuedo-force?

Hello, this question is born out of my first semester of lab coursework where for the first time, I was properly introduced to understanding error propagation. I'll get right to the question and expand upon it afterwards. What is the role of theorems in physics? I've heard people go on and...

I have been trying to find out of Boyle's Law and plate tectonics are in any way shape or form related. Are they? If they are not, is there a way I can relate their movement to physics?

Homework Statement I did an experiment investigating what effect height has on force and now i need a theoretical value to compare it to Homework Equations f=ma but i don't think acceleration is constant here The Attempt at a Solution f=ma f=0.104x9.8 f=1.01 i got 49 N with...

In which situation is Work done (F.d) equal to Kinetic energy, Potential energy and both kinetic & potential energy at the same time?

Homework Statement It turns out there is a relation between angle a and angle b. I can't figure it out, could someone give me a hint? There's a lightray that is bouncing from two mirrors (m1 and m2). The angle between those two mirrors is called a. The angle between the incoming lightray l1...

Hello, I was wondering is there a relation between the refractive index of the material and the amount of light the material absorbs (e.g. the higher n means higher absorption)? If so what is then a relation between the intensity of the light and the refractive index? p.s. I am trying to...

I am asked to show that when \(\hat{e_r}\), \(\hat{e_\theta}\), and \(\hat{e_\phi}\) are unit vectors in spherical coordinates, that the cartesian unit vectors $$\hat{i} = \sin{\phi}\cos{\theta}\hat{e_r} + \cos{\phi}\cos{\theta}\hat{e_\phi} - \sin{\theta}\hat{e_\theta}$$ $$\hat{j} =...

Hi guys need help. We've been encountering compressed dry-air related problems here in our plant. Most machines pressures were fluctuating when their equipments are running. As I've checked, the problem is not regarding the pressure since the line pressure is 10psi higher than machine...

If the radiation flux is calculated as: F = \frac{L}{2*pi*r^{2}} where L is the luminosity of the source and r is the distance from the source and the count rate of a scintillator \frac{number-of-scintillations}{time} What is the relationship between them? There obviously should be one, as...

Is there a profound relationship between Principle of Least Action and Continuity Equation? Can we derive one from another?

If I 8000 gpm flowing in a pipe, and know that pressure of the water is 55psig, will the pressure be 27.5psig if the flow rate through the same pipe drops to 4000gpm.

Hello, I have started reading a beginners book (from the "stop faking it" series) on electricity and magnetism. Its supplied with funny little experiments to help me understand the topic. But I have trouble understanding the intimate relationship between electricity and magnetism. I believe I...

Hi all, I need to model an hydraulic cylinder with simulink and to control it according to some rules. What I don't understand is to find a relationship between the flow rate and pressure inside it. Any suggestion is appreciated. Thanks

From a biochemical context, considering the following two dissociation reactions and their respective dissociation constants for a protein-ligand complex: P*A + B ⇔ P + A + B, this contains the a dissociation constant called Ka = 4 x 10^-3 M P*B + A ⇔ P + A + B, this contains the a...

I am doing a project of an entity relationship model and a doubt came: Should repeated attributes of the entities be shared? Or I must reproduce these to every entity? In another words, if two of my entities are books and magazines, shall I have a single publisher attribute, or one for each?

I am trying to conceptually understand this relationship. One thing that's not helping is I keep hearing the phrase "the resting length" of muscle. It's using the word "THE" as if there is one resting length. This phrase implies that the length stays the same no matter how bent my elbow is at...

I might as well start from the beginning here. My girlfriend and I have been seeing each other for a little over 6 months now. We had some problems in the beginning, but we worked them out. For 5 months, we not only had the epitome of perfect relationships, but we were best friends. Every...

Homework Statement A ball rolls around a horizontal circle at height y inside the cone shown below. Find an expression for the ball’s speed in terms of r(radius of cone),x(height of cone),p and g(9.81ms^-2). Homework Statement r(radius of cone),x(height of cone),p and...

Exercise 22 on p108 of Schutz's 'A first course in General Relativity' is to prove that, for an isotropic, monochromatic, photon gas, p=ρ/3, where p is pressure and ρ is mass-energy density. When I try to do it I get p=ρ/6. I was hoping somebody could tell me where I'm going wrong. Here is...

Second moment of area "I" and deflecton relationship Homework Statement What I value will halve the beam deflection Homework Equations I = bd^3 / 12 and y max = - 5wL^4 / 384EI The Attempt at a Solution Transpose y max = - 5wL^4 / 384EI to: I = - 5wL^4 / 384Ey max...

Hi all, just a quick problem that I really cannot get my head around, any help would be appreciated. Homework Statement State, in detail, how the frequency affects the number of antinodes produced on string with a fixed tension, density and length. Homework Equations The frequency of a...

Ok, so I'm not really too good at group theory and that kind of math, so I hope I can explain my question: I tried to evaluate \frac{d}{dx}e^{x}: \frac{d}{dx}e^{x} = \frac{e^{x+h}-e^{x}}{h}, h -> 0 = \frac{e^{x}e^{h}-e^{x}}{h}, h-> 0 = e^{x}(\frac{e^{h}-1}{h}), h-> 0 So I figured...

Homework Statement Use the approximate relationship to prove: Δf~\frac{df}{dx}Δx a) \frac{dx^{n}}{dx}= nxn-1 b)\frac{dcos(θ)}{dθ}=-sin(θ) Homework Equations a)N/a?? I'm not sure if I need any other equations than the one given. b) sin(ε)~ε and cos(ε)~1 when ε<<1. The Attempt at...

Hi! I am extremely confused on what seems to be quite a simple question. The question contains a graph of root mean square radius <r^{2}> plotted against A^{1/3} where A is the nucleon number. In the lecture notes he specifies that <r^{2}> is not the same as R but does not really say...

Hey everybody, My friend is in graduate school and has been having problems with his adviser. Let me back up a bit here, they used to be on good terms, but more recently his progress has stagnated because his adviser won't meet with him. Also, his adviser has been losing patience due to his...

[FONT="Arial"]Is there a formula that shows the relationship between AC power and DC power? Something on the lines of, for example: Power of AC ... = Power of DC ... ? Thank you.

I'm studying engineering dynamics. The first chapter is discussing the velocity and acceleration equations; v = ds/dt and a = dv/dt. It then goes on to show a third equation that is stated as "a ds = v dv". They say they derived this equation by combining the two previous and 'eliminating dt'. I...

Homework Statement Given tthe following voltage and current i(t) = 5sin(377t - 20°)A v(t) = 10cost(377t + 30°)V Determine phase relationship between i(t) and v(t) Homework Equations wave functions wave properties The Attempt at a Solution Would the phase relationship simply be 50°...

I have a question/assumption that I'm not sure whether or not it is correct. Imagine I have an electric motor, if I have this motor spinning a load at a certain speed, can I assume that there is constant torque? That is, as long as the load isn't changing. However, if the load changes and...

I'm looking for an equation similar to the change in forward momentum equation: Δmv=f*Δt But for angular momentum. I think it will be (change in angular momentum) = (torque) * (change in time) Here is how I derived it: Is this all correct? I cannot find this equation anywhere on the...

Well, I didn't know where to post this rather philosophical stuff, so decided to put it here. But I promise it is related to all sciences mentioned above. Here is the setting. Whenever we prove something mathematically, we always think that the proof is "eternal", often contrasted with the...

So I've been simulating a really simple geometry using ANSYS Maxwell. It is a cylinder only and I am looking at the \overrightarrow{B} and \overrightarrow{H} fields in order to see their relationship between them when the material is magnetized in the circumferential direction. I used a...

From the Greiner (Thermodynamics and statistical mechanics) on the relationship between the number of microstates of two systems and the total entropy: ...for two statistically independent systems the total number of compatible microstates \Omega_{tot} is obviously the product of the...

Is there a proof or obvious reason why the vertex function is related to the current via: S(p')\Gamma^\mu(p',p)S(p)=-\int \int dxdy e^{ipx}e^{-ipy} \langle T \psi(x) j^\mu(0) \bar{\psi}(y)\rangle In the free-field case one can see it's true. But the interacting case?

Why is V=fl a "dispersion relationship"? I've heard of V=fλ being referred to as "the simplest dispersion relationship", however it seems to be used to describe non dispersive traveling and standing waves, where the wave velocity is determined by the medium (fixed) and either f is a dependent...

Hi everyone, I am curious as to whether it is possible to calculate the difference in density due to applied (mechanical) stress on an object. E.g.: apply a controlled force of, say, 50 N on a structure, calculate the mechanical stress in the object with sigma = M/I * z and then go on from...