Conditions Definition and 978 Threads

What were the necessary conditions to allow a big bang to occur?

is it possible to create antigravity conditions on earth?if so,how?

\frac{dN}{dt}=-k_sN^2 Attempt: \frac{1}{N^2}dN = -k_s dt Integrate: -\frac{1}{N} + C = -k_s t In the solution manual, C is written \frac{1}{N_0} Why?

This is the circuit at t(0-); Initial conditions need to be determined: Capacitor is replaced by an open circuit and inductor is replaced with a short circuit: These are the initial conditions I get: I through inductor (0-) = 3 A V across capacitor ( 0-) = 0 ( in parallel w/ SC)...

I'm reposting this because there was a problem with the title/LaTeX last time. Homework Statement Solve the wave equation (1) on the region 0<x<2 subject to the boundary conditions (2) and the initial condition (3) by separation of variables.Homework Equations (1) \frac{\partial^2...

Though this question arose in quantum mechanics, i think it should be posted here. Consider a particle in a well with infinite walls: $i i \frac{\partial \Psi}{\partial t} = -\frac12 \frac{\partial^2 \Psi}{ \partial x^2},\:0<x<a$ but the wall start to squeeze :devil: $\Psi(x=0,t) \equiv...

This thread will attempt to bring together "vagueness" based approaches to going beyond the standard model. Vagueness gives a different way to model the Universe's initial conditions. (And also quantum indeterminacy, the two being not un-related). Vagueness in logic means indistinct...

A: 1-mt<w^2(m+t) B: -(1+mt)<(w^2 )t(m-t) i have 4 cases for each case they said that needs to be a condition for which this case would be true 1: m>t and mt<1 so they say that i have to demand w^2>(1-mt)/(m+t) which is inequality A 2: m<t and mt<1 they say that i have to...

Can you help me with this? I have a function with domain and range in R^2. What conditions it must have so that a point in the boundary of the domain will have its image in the boundary of the range? Thanks.

Homework Statement Homework Equations N/A The Attempt at a Solution Really stuck with this, i can't work out how to apply the boundary conditions to generate the simultaneous equations to find the specific solution. Can't find any similar examples either. Help appreciated.

Hi, I'm slightly confused about one aspect of the conditions for applying L'Hopital's rule. N.b. apologies in advance for the lack of LaTeX. L'Hopitals rule: Let f,g:(a,b) → R be differentiable and let c ε (a,b) be such that f(c)=g(c)=0 and g'(x)≠0 for x≠c. Then lim(x→ c)[f(x)/g(x)]...

Homework Statement Homework Equations N/A The Attempt at a Solution The problem and attempt are as above, I'm not sure where to go from here though. I'm not sure what to do with the boundary condition of dx/dt=-2 and t=0. Any help appreciated.

The plane that contains the line x = -2 + 3t, y = 4 + 2t, z = 3 - t and is perpendicular to the plane x - 2y + z = 5.

Maximum air velocity in ambient conditions?? Masters what is the maximum air velocity that can be achieved in ambient condition?? In the throat of sonic nozzle it attains sound velocity. Is it possible to attain more? If yes how?? thanks

Homework Statement Given \vec{}r"(t)= 6i-4cos (2t)j+ 9e3tk, r'\vec{} (0)= 4i +3k and r\vec{}(0)=j+k, find r\vec{}(t). Homework Equations The Attempt at a Solution I will appreciate any ideas how to start this problem. Thank you.

what do boundary conditions mean wid respect to transmission lines??

Don't fly into known icing conditions. http://d.yimg.com/img.news.yahoo.com/util/anysize/400,http%3A%2F%2Fd.yimg.com%2Fa%2Fp%2Fap%2F20090213%2Fcapt.47ac24e5a3de43cf8e46f8a78db23205.plane_into_home_nydd113.jpg?v=2 Pilot error...

Hi all! I've appreciated (and lurked :-) this forum for a while. While waiting to find a question I'm able to answer, it's time for my first post (hopefully the first of many). Here's the problem: I'm trying to teach myself euclidean geometry and a found a tough (for me) question to answer in...

Homework Statement Let T be defined on F^2 by (x1,x2)T=(w*x1+y*x2, z*x1+v*x2) where w,y,z,v are some fixed elements in F. (a) Prove that T is a homomorphism of F^2 into itself. (b) Find necessary and sufficient conditions on w,y,z,v so that T is an isomorphism. The Attempt at a Solution I...

Homework Statement Hi all. I have the following expression, which relates the incoming amplitude with the reflected amplitude at a point x = L in a coaxial cable: A_{\text{reflected}} = \frac{R-Z_0}{R+Z_0}A_{\text{incoming}}. Here R is the resistance at the point x = L and Z0 is the...

what are the rank conditions for consistency of a linear algebraic system? my proffessor said that the coefficient matrix augmented with the column value matrix must have the same rank as the coefficient matrix for consistency of the system of equations. however does the term rank apply to...

Homework Statement One half of the region between the plates of a spherical capacitor of inner and outer radii a and b is filled with a linear isotropic dielectric of permittivity \epsilon_1 and the other half has permittivity \epsilon_2, as shown in the figure. If the inner plate has total...

Hi, I have been given a differential equation to use in order to solve for the Hydrogen wavefunction in the ground state using Euler's method. d^2u_nl/dr^2 -(l(l+1)/r^2)*u_nl + 2k*(E_nl-V(r))*u_nl = 0 V(r) = -a/r where a = 1/137.04 I have been given initial conditions u_nl(0) = 0 an...

Homework Statement What conditions need to be imposed on \vec{E}0, \vec{B}0, \vec{k} and ω to ensure the following equations solve Maxwell's equations in a region with permittivity ε and permeability µ, where the charge density and the current density vanish: \vec{E} = Re{ \vec{E}0...

I am trying to solve an ode of the form u"(x)=a(x) where a(x) is some known function and the domain is from -inf to +inf. I am required to use Green's function. The boundary condition is u(0) = Integral[u(x),{x,0,1}] = 0 My Green's function has the form G(x,y) = A(y)*x+B(y) x<y G(x,y)...

Find unit vetors satisfying qualifying conditions! HELP test tomorrow Homework Statement Find the unit vectors satisfying qualifying conditions: a. oppositely directed to 3i-4j b. same direction as 2i-j-2k c. same direction as vector from A(-3,2) to B(1,-1) Thoughts. Ok...

Homework Statement Calculate potential function and the electric field for the region between two concentric cylinders, where V ( inner cylinder) = 0 at r = 0.015 m and V(outer cylinder) = 100 for r = 0.025 Homework Equations \Delta (square ) V = 0 The Attempt at a Solution so...

Hi. You know that B_{1n} = B_{2n} as one of the boundary condition when magnetic field is go across from material 1 to material 2, n means direction perpendicular to the boundary surface. I wander this theorem is right in non-uniform field which is function of space variable r...

Homework Statement Calculate the volume of H2 required to completely hydrogenate 50 grams of glycerol trioleate at 1 atm pressure and 25 degrees Celcius. The ideal gas constant is 0.082. Homework Equations I am unsure if I need the Ideal Gas Equation or not. I know that the ideal gas...

Hi all, a quick question, if we assume zero inital condtions does that mean that we replace each voltage source by a short circuit and a current source with an open circuit??

Firstly I really feel so lucky to find this forum. Since I don't have a strong physics background but now dealing with many problems directly related to physics. I'm now doing some simulation in comsol and need to solve some PDEs. I'm using this PDE coefficient form in comsol. The equations...

Homework Statement Hi all. I am given the following differential equation: X'' - k*X=0. I am told that k = -m^2, so the general solution is given by: X = a*cos(m*x)+b*sin(m*x), where a and b are constants. I am also given boundary conditions: 1) X(-Pi) = X(Pi) 2) X'(-Pi) =...

I don’t know if the question belongs to engineering or math but here it goes. I was taught that a sufficient (not necessary) condition for existence of Fourier transform of f(t) is f(t) is absolutely integratble. I was wondering what are the “necessary and sufficient conditions” for FT of f(t)...

Homework Statement Solve Laplace's equation inside the rectangle 0 \le x \le L, 0 \le y \le H with the following boundary conditions u(0,y) = g(y)\text{, } u(L,y) = 0\text{, } u_y(x,0) = 0\text{, and } u(x,H) = 0 Homework Equations The Attempt at a Solution I know that with...

Free Electron Model: Why periodic boundary conditions and what is "L"? Right, hello! The quantum free electron model for electrons in solids (in One dimension) says we need to use periodic boundary conditions such that if Y(x) is the wavefunction, then Y(x) = Y(x+L). Where L seems to be...

The functions K maps to f(K) and C maps to U(C) are given as: F(K) = aK and U(C) = -C^2 +b here a and b are positive constants. the initial and teriminal conditions with the triminal time T = 1/a are K(0) = K_0 and K_T = K(1/a) here K_0 and K_T are positive constants. Write Euler...

A strange list, but this looks like bull**** http://www.oddee.com/item_96473.aspx

This should be a dead simple answer, but I don't know what this is called, or what to search on... I need a function of x such that: 0 <= x <= 1 Where f(0) = 0, and f(1) = infinity. I also need the curve to be relatively flat for "lower numbers", say up to 0.3, and begin a very sharp...

Mods: I wasn't sure if I should put this here or in DE's, if you think it would be better there, feel free to move it. Everyone: If I have a bunch of particles, which I'm modelling as a continuum, and I want to put periodic boundary conditions which reflect (completely specular reflection)...

Hey folks, I'm trying to find the Green function for the equation -\partial_\mu \partial^\mu \phi = K where K is some source term. Its a 2D problem with the wave confined to a rectangular cavity where the cavity is located at z = 0 and z=a. This tells me that G|_0= G|_a=0 I've pretty...

Let G be a finite nonempty set with an operation * such that: 1. G is closed under *. 2. * is associative. 3. Given with a*b=a*c, then b=c 4. Given with b*a=c*a, then b=c Give an example to show that under the conditions above, G is no longer a group if G is an infinite set?

Homework Statement given this ODE with initial conditions y(1)=0 \[ (x + y^2 )dx - 2xydy = 0 \] Homework Equations solving this ODE gives us \[y = \sqrt {x\ln (x)} \] as we can see this equation is true only for x>=1 in order to use the theorem on existence and uniqueness we isulate...

Hey people can u please tell me what will be the boundary conditions for a circular plate with a central hole clamped at the circumference... Plate is axis symmetric and is under uniform load..

What are the general boundary conditions for nonviscous, incompressible fluid flow? I am trying to find the velocity of fluid at the surface of a sphere with the incident fluid having uniform velocity. I am surprised to find in the solution that the radial velocity at the surface does not...

Under what conditions does a function have a power series representation? I am looking for a theorem that says if a function satisfies these conditions then it has a power series representation. Or does all functions have a power series representation?

Hi all, could someone give me a quick answer on the exact conditions for the hamiltonian to be non degenerate, i.e. to have different eigenvalues? thanks in advance.

I can't understand this conditions, and in general every boundary conditions for problems like this. they states "the choice of boundary conditions can be determined by mathematical convenience (!?) ... for if the metal is sufficiently large, we should expect its bulk properties not to be...

Hello friends, Thanks in advance for your answers, I am using genreal form of PDE to solve system of PDEs. I am dealing with cyllindrical co-ordinates under axisymmetric case. I am not able to understand how to implement boundary conditions such as, DEL. Gamma=F is system of PDEs where...

Hi Guys! *waves* Anyway, I was just wondering what conditions and in what state are atoms sufficiently isolated so that it gives rise to a line spectra. I thank you all for any help you provide in advance. Many thanks, Icetray

Hi I'm trying to solve a magnetostatic problem and I'm not sure which boundary conditions must be applied to the magnetic vector potential (A) on magnetostatic problems? Thanks in advance.