Change Definition and 1000 Threads

Sorry if this question has been asked before or is common knowledge. It seems to me that when one or more electrons in an atom is excited to a higher energy state, then the effective potential experienced by other electrons should be different from the potential in the ground state. Hence the...

So for GLMs, what is considered a large change in deviance? If I go from 3500 in one model to 3200 in another, does that mean that the second model is better?

MENTOR NOTE: NO TEMPLATE BECAUSE SUMITTED TO WRONG FORUM. 3.1) A quantity of 0.10 mol of an ideal gas A initially at 22.2 degrees C is expanded from 0.200 dm3 to 2.42 dm3 . Calculate the values of work (w), heat (q), internal energy change (delta U), entropy change of the system (deltaSsys)...

Homework Statement Hi I have the following definition for the partition function of ##N## particles in ##s## dimensions: I am looking at computing the partition function for this Hamiltonian: The solution is here: Homework Equations above The Attempt at a Solution I don't...

Homework Statement : [/B]Find the change in internal energy of 2kg water as it is heated from 0°C to 4°C. The specific heat capacity of water is 4200J/Kg and its densities at 0°C and 4°C are 999.9 kg/m3 and 1000kg/m3 respectively. Atm pressure=105PaHomework Equations :ΔU= Q-W W=PΔV M/V=D[/B]The...

Imagine we take a vertical, infinite wire and we let electric current pass through. The charges create magnetic field all around the wire. Now if we introduce an electron in the magnetic field, it will have a circular motion around the wire. The Lorentz force is not conservative, this means...

I would like to know why electric field of EM waves changes it's direction to opposite when hitting a conductor surface. I know that electric field inside a conductor is zero but I am not able to connect these two situations.

Homework Statement A steam turbine in a small electric power plant is designed to accept 4500 kg of steam at 60 bar and 500oC and exhaust the stem at 10 bar. Part C. In off-peak hours, the power output of the turbine in part a) (100% efficient) is decreased by adjusting a throttling valve...

Hello, I am new here , I am 28 years old with a Linguistics Master degree and a three years experience as a language teacher at University. Since my childhood I was fond of engineering and Physics, but unfortunately and due to some personal circumstances I was not able to pursue a degree in...

I think I do not quite understand the role that change of basis plays is superpositioning of states. If there is an observable, ##A## which is represented by the operator ##\hat{A}##, then the set of observed values for that observable will be the set of eigenvalues defined by the operator...

Homework Statement Hi guys, it a very simple question, but it causing me a great deal of confusion. The questions are as follows: So I worked out the ans for one which I have displayed below. But what I don't understand is what they want from the second question. Because the way I see it...

If you have a free neutron viewed from a known frame of reference which is known to be spin up and it decays, is there anything in theory or experiment which indicates whether the remaining proton will be spin up or down? Thanks Jerry

Homework Statement I am trying to minimize the function ##f(a) = (1+4a^2)^3 \left( \frac{1}{4a^2} \right)^2##. Here we are given that ##a>0## Homework Equations Definition of a minimum of a function The Attempt at a Solution Now the derivative here will be ugly and equating it to zero and...

When we rotate a disk, can this process be fully explained by looking worldlines of the particles the rotating disk is composed of, hence their x,y,z,t position "as time passes", or do particles have some kind of "facing direction", hence also spin(not the quantum mechanical notion of spin)...

From reading textbooks, we just know that there is a pressure difference because the fluid speeds up. But WHY is there a pressure difference, why does the pressure decrease?

Let’s suppose we have an electron with a Gaussian eigenstate, as the time runs, the wave spreads in space without changing its energy, however, the induced EM field caused by the particle decreases its energy. I assert this from the classical electromagnetism result in which the more...

Homework Statement Homework Equations N/A The Attempt at a Solution I solved part a. I got an answer of 140. For part b, however, I am stuck. I came up with a set of points for D in the xy plane [(0,3)(0,6)(4,5)(4,8)] giving me a rhombus. How do i integrate this? I tried to split up the...

I am currently studying a Foundation Program, which includes chemistry. -I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration. -But how can an tom changes from ground to excited state ? And can an atom changes from...

Exactly how does a mouse brain and or body record a shock to mouse feet to mouse sperm cells. If you are familiar with the mouse experiment I find this fantastic, not so much because of what it shows, but because no one cares enough to expand upon it as it invalidates natural selection over a...

Hi, I'm trying to evaluate the derivates of first, second and third order of the phase change parameter in a dispersive medium. In such medium the refractive index is a function of the wavelength. In my case it depends on the wavelength in vacuum. \begin{equation*} n(\lambda_0 )\end{equation*}...

I am working on planetary orbits in an ellipse where the sun is at the foci, not the centre of the ellipse. I need a formula that describes the 'Change of Distance by Change of Theta angle' where Distance represents the distance between a planet to the sun (Planet is on parameter, Sun is at...

Are there any cosmological models that say that the shape of the universe changes with time? As in it may oscillate between being a sphere, torus , saddle or a plane? I remember the course in Astrophysics that I took in my BSc studies, and we had it that the shape of the universe depends on...

Homework Statement An AC source was connected to a capacitor and an inductor (ignoring its ohmic resistance) in series. If the inductive reactance was equal to twice the capacitive reactance, and then the frequency duplicated, determine: 1. the relationship between the the current before and...

Homework Statement Determine the spherical harmonics and the eigenvalues of \vec{\hat{L}}^2 by solving the eigenvalue equation \vec{\hat{L}}^2 |\lambda, m \rangle in position space, [\frac{1}{sin \theta} \frac{\partial}{\partial \theta} ( sin \theta \frac{\partial}{\partial \theta} ) +...

Homework Statement Given the reaction K2CO3(s) + 2HCl(aq) → 2KCl(aq) + CO2(g) + H2O(l), I need to find the enthalpy change in J, given that: The specific heat capacity of water is 4.2J g-1 °C-1, and The mass change of potassium carbonate is 2.98g, and the temperature change was °6C, and the...

How did this definition come to Newton's mind? Force seems to be the effort we apply. So, qualitatively, more the effort, more the force. How to understand intuitively that this formula given by Newton gives a quantitative measure of Force? And, how do we know that Force does not depend on more...

Homework Statement A particle in an infinite potential well ##V(x) = 0, -\frac{a}{2} \leq x \leq \frac{a}{2}##, and infinite elsewhere is in it's ground state. Subsequently, the potential is removed and the particle is free to move. How does the probability distribution in x and p change...

Hello! I have this GRE question: In process 1, a monoatomic ideal gas is heated from temperature T to temperature 2T reversibly and at constant temperature. In process 2, a monoatomic ideal gas freely expands from V to 2V. Which is the correct relationship between the change in entropy ##\Delta...

What causes the change in the axial tilt of the earth? Why does it change?

Homework Statement A closed, rigid tank contains 2 kg of water, initially a two phase liquid–vapor mixture at T1 = 70°C. Heat transfer occurs until the tank contains only saturated vapor at T2 = 120C. Determine the heat transfer for the process, in kJ. answer choices: 3701kJ 119.4kJ 4835kJ...

Hi. I realize that Jacobians are not normally used in 1-D but I'm confused as to the following. If I have the following integral ∫a-a f(x)dx and make the change of variable y = -x then dy = -dx and the limits of integration reverse so I end up with ∫-aa f(-y)(-dy) but if I use the Jacobian...

Homework Statement "One way to heat a gas is to compress it. A gas at 1.00 atm at 25.0°C is compressed to one tenth of its original volume, and it reaches 40.0 atm pressure. What is its new temperature?" So, I have: P1 = 1 V1 = 1 T1 = 25 P2 = 40 V2 = 0.1 And I'm looking for T2 The question was...

It's been a long time since I've worried about this - but could someone help me make Pr(x) the subject (I can't remember if it's possible, if it's not, I'd love a brief explanation): T = S [(1-Pr(x))^N] + Pr(x) Thanks in advance!

How does air resistance change the maximum height of a projectile ?

Say, we have two orthonormal basis sets ##\{v_i\}## and ##\{w_i\}## for a vector space A. Now, the first (old) basis, in terms of the second(new) basis, is given by, say, $$v_i=\Sigma_jS_{ij}w_j,~~~~\text{for all i.}$$ How do I explicitly (in some basis) write the relation, ##Uv_i=w_i##, for...

Hello, I am currently trying to get my head around the concept of entropy. One way to understand it is that it can be related to the amount of available energy levels in a system. From what I read, the availability of energy levels in a system: 1) increase with an increase in the system...

Hello everybody, My question is about change of frame of reference and its consequences on an ordinary function. Let's ##B## a frame of reference that is linked to another one ##B'## through a change of basis matrix ##M##. So, for an equation written in the first basis ##B## as...

Hi All, $$\int{\exp((x_2-x_1)^2+k_1x_1+k_2x_2)dx_1dx_2}$$ I can perform the integration of the integral above easily by changing the variable $$u=x_2+x_1\\ v=x_2-x_1$$ Of course first computing the Jacobian, and integrating over ##u## and ##v## I am wondering how you perform the change of...

Homework Statement A uniform electric field of magnitude 4.1 ✕ 10^5 N/C points in the positive x-direction. Find the change in electric potential energy of a +5.3 µC charge as it moves from the origin to each of the points given below. (a) (0, 6.9 m) __ J (b) (6.9 m, 0) __J (c) (6.9 m...

Homework Statement Consider the function ##f(x) = x^4 \sin(\frac 1 x)## for ##x \ne 0## and ##f(x) = 0## for ##x =0##. I have to prove that ##x=0## is the critical number of this function and its derivative changes the sign indefinitely. Homework Equations Definition of the critical number...

Firstly, and most importantly: I am not interested in getting into a debate about climate change in this thread. If you try to engage in debate with me in this thread, I will immediately abuse my administrative powers and physically delete your post! (Devil) Secondly, I want to make it clear...

We know that while deriving the special theory of relativity formulas like Lorentz Transformation, Length contraction, Time dilation etc, we assume that there is an observer at each point of the space in a certain frame and all these observers contain synchronized clocks and scales. But what if...

Q: Suppose ##u(x,t)## satisfies the heat equation for ##0<x<a## with the usual initial condition ##u(x,0)=f(x)##, and the temperature given to be a non-zero constant C on the surfaces ##x=0## and ##x=a##. We have BCs ##u(0,t) = u(a,t) = C.## Our standard method for finding u doesn't work here...

According to the first law of thermodynamics, dQ = dU + dW and you can find dU = nCvdT If this is the case then when water at 100°C vaporizes to steam at 100°C shouldn't the change in internal energy be zero because it is dependent on temperature change?

Homework Statement (a) A transmission line has a length, ##l##, of 0.4λ. Determine the phase change, ##\beta l##, that occurs down the line. Homework Equations ##\beta=\frac{\omega}{f\lambda}## or ##\beta=\frac{2\pi}{\lambda}## The Attempt at a Solution This question was posted a couple of...

Hello friends. I'm an economics major who felt too unconfident in his math skills to enter physics. Two semesters into college, I realize that I know enough math for intro courses. So, to be honest, I'm considering returning to physics. However, I have taken (and will take) NO math or physics...

Imagine a situation in which a space time curvature propagation reaches a zone (in space time) which it had no prior influence. Would the measured motion (for the objects in that rough zone) in spacetime (subsequently) be unaffected by the changes in spacetime curvature? If the answer was "yes"...

Consider three identical boxes of volume V. the first two boxes will contain particles of two different species 'N' and 'n'. The first box contains 'N' identical non interacting particles in a volume V. The second box contains 'n' non interacting particles. The third box is the result of mixing...

Hello everyone, conservative forces only depend on position (cannot depend on time), i.e. ##F(x)## and are equal to the spatial derivative of the potential energy function ##U(x)##: $$F(x)= - \partial U(x)/\partial x$$ Conservative forces always have to change the kinetic energy KE and...

For example if you send a light beam towards a massive object the propagation speed will reduce if μ and ε are increasing, but the spacetime curvature will compensate for that reduction.