# Tagged Questions

DO NOT USE THIS TAG just because the question contains a differential equation!

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### Which formulas would tell me the gradient of an electromagnetic field at an arbitrary distance from a pole? [duplicate]

I'm a newbie to physics and was wondering where I can read about electromagnetic gradients. From what I understand (and my intuition) electromagnetic fields create force gradients around its poles. ...
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### Linear viscoelastic differential operators

I am starting with differential operators: $P = \sum_{i=0}^{N}p_i \cfrac{d^i}{dt^i}$ $Q = \sum_{i=0}^{N}q_i \cfrac{d^i}{dt^i}$ $p_i$ and $q_i$ are functions of time only. $K$ is a constant that ...
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### Can $Ae^{-bt^2}\sin(kx-\omega t)$ be considered a wave?

The damped wave PDE can have an exponential term, but the argument for the exponential term cannot be quadratic, AFAIK. $Ae^{-bt^2}\sin(kx-\omega t)$ So this isn't a solution for the damped wave PDE....
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This is a basic question regarding state space representation and differential equations. I want to find the time response of states $x_{1} = x$ and $x_{2} = \dot{x}$ of the following system: $$m\... 1answer 82 views ### Existence and Uniqueness of Newton's Laws I'm reading Arnold's book on classical mechanics. This is kind of a dumb question, but I'm having problems understanding his explanation for existence and uniqueness of Newton's laws. On page 8 he ... 0answers 23 views ### Lets consider a cube with side 2, which is cooling in an environment. Find its temperature at any point at any time: u(x,y,z,t) Lets consider a cube with side 2, which has an initial temperature of 1Â°K and it is cooling in an environment of temperature 0Â°K. Find its temperature at any point at any time: u(x,y,z,t). ... 1answer 77 views ### Monodromy matrix and differential equations What is the significance of monodromy matrix in the context of differential equations? I have seen some papers(1,2,3 etc) in CFT which use the monodromy method to compute conformal blocks at large ... 1answer 30 views ### How to extract heat transfer model parameters from empirical data? I have made a simple model of heat transfer between ambient and a silicon chip (module) from which I can read its internal temperature T_m. I do not need fancy equations and an approximate model ... 0answers 41 views ### car dashboard problem I stumbled upon this question while I was driving my car. On my dashboard I have fuel gauge and engine temperature gauge next to each other, look at the pic: http://i.stack.imgur.com/aDgKj.png Fuel ... 1answer 159 views ### Solution of QM tasks by using asymptotics When we solve QM tasks by solving the SchrÃ¶dinger equation, such as tasks about a particle in a Morse potential, a Poschl-Teller potential and many others, we usually find approximations (lets call ... 0answers 40 views ### Question about a solution of a partial differential equation by separation of variables I'm trying to understand this text: http://www.ekayasolutions.com/UCDMath/HeatCondSphere.pdf But I'm having problem with this part: Whe have to solve: \dfrac{\partial \theta}{\... 1answer 47 views ### Differential derivation based upon time and space confusion I have been doing a lot of derivations recently involving heat transfer. I was attempting to derive heat accumulation in a differential element based upon inflow and outflow as well as thermodynamic ... 2answers 86 views ### Interpretation of Eigenvalues and Eigenvectors of an hyperbolic conservation law \partial_t W + A \partial_x W = 0 I read in a article dealing with a hyperbolic partial differential equations this statement : For any system of hyperbolic partial differential equations (pde), expressed as (1) \... 0answers 56 views ### What type of differential equation is this? [closed] Need to find the general solution and characteristics, but I can't define type of this differential equation  u_{ttx}=u_{tx}^3  1answer 81 views ### A model for constant temperature of water in a container I put some water in a container with initial temperature T_0 in a room, and the room's initial temperature is T_a. Now the container is filled to the maximum, so any more water coming in will ... 0answers 18 views ### Is there a “natural” way to interpolate between a set of bound state wave functions? Consider for example the Coulomb potential, -Z/r, for which there exist a set of bound states with energy \epsilon_n := {-Z^2 \over 2 n^2} (in Hartree). If I want the "wavefunctions" for some ... 0answers 28 views ### Cooling of a surface due to fluid passing over it I am working on a project that requires me to measure the cooling effect of a liquid flowing through a surface. In order for me to effectively calculate the cooling effect, the solution of the below ... 1answer 98 views ### Numerically solving a simple Schrodinger equation with fast Fourier transforms While trying to solve a stochastic Gross-Piaevskii equation I have found a problem that can be tracked down to something buggy occurring in the simplest Schrodinger equation possible:$$\partial_t \...
While studying certain analogue gravity models I came across a differential equation of the form: \begin{align} \frac{d^2y}{dz^2} + \omega^2 (z)~ y(z) = 0 \end{align} where $z$ is a complex variable ...