Example Definition and 879 Threads

Given the following image of 2 conductors, a negatively charged inner ring and positively charged outer ring, taken from http://www.physicsclassroom.com/class/estatics/u8l4d.cfm" Where are the electrons located in the outer ring? If there was no inner ring, and as the outer is...

Find the expectation value of the potential energy in the nth state of the harmonic oscillator. This is his example 2.5 in the book, he uses a\pm=1/Sqrt[2hmw](\mpip+mwx) to get x=Sqrt[h/2mw](a_{+}+a_{-}) My question how does he do this? I can't seem to make the algebraic manipulations to...

A reaction is Spontaneous means what??a reaction is favorable? let me give an example:-By taking a Balloon and blowing air into it we are imparting Energy to the Balloon as the KE of the air molecules so was this reaction spontaneous? or the reverse is spontaneous i.e leave the balloon and let...

the general form of state space output is y=cx+du which means that output is linear combination of state variables and inputs my question is can we write output in this form when our output is not combination of state variable for example in rlc circuit state variables are vc and IL now if we...

Ok I am only a physics undergrad so if this is obvious I am sorry. I understand the concepts of SR pretty well but one thing has bugged me. In the most basic light clock example used to describe the effects of time dilation, where 2 mirrors are placed 1 ls apart on a moving boxcar with an...

Homework Statement https://www.physicsforums.com/attachment.php?attachmentid=39373&stc=1&d=1317244721 Homework Equations In all honesty I am not sure? The Attempt at a Solution This question was used as a worked example in my first tutorial for Dynamics. The lecturer didn't break it down...

good day, this is the multiplication property of equality rule a * b = b * c but is this the multiplicative equality too: a * x = b thank you so much have a good day asburyparknj

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Homework Statement Let X = R2 with the Euclidean metric and let S = {(x1, x2) : x1^2+x2^2 <1}.Prove that Closure of S ={(x1,x2):x1^2+x2^2<= 1} and that the Boundary of S= { (x1, x2) : x1^2 +x2 ^2=1 } . Homework Equations The Attempt at a Solution I was able to prove all my...

As i know, the metallic structure for example a pure copper metal which is made up of all metal atoms that is the copper atoms actually have all its atom of metallic element bonded together by metallic bonding. Metallic bonding is the electrostatic force of attraction between the positively...

please the exmple for wims

Hey folks, I'm trying to find out if a more luminous, less massive body can orbit a more massive, less luminous body (is this an obvious question?). Can such a thing happen? Can it happen in a binary system perhaps..? By less massive I'd also like to know if it can mean the smaller mass being...

Homework Statement What sampling frequency would you use to sample the following signal x(t) = 3sin(9πt) - 6cos(8πt)Homework EquationsThe Attempt at a Solution let T1 be the period of 3sin(9πt) and T2 the period of 6cos(8πt) T1 = 2π/9π = 2/9 Τ2 = 2π/8π = 2/8 thus, if f1 is the frequency of...

Homework Statement two long cylinders (radii a and b) are separated by material of conductivity (sigma). if they are maintained at a potential difference V, what current flows from one to the other, in a length L? Homework Equations Please see the attachment The Attempt at a Solution...

Homework Statement http://www-thphys.physics.ox.ac.uk/people/JamesBinney/complex.pdf Example 1.2 (Page 6) Homework Equations De Moivre's Theorem, Euler's Formula, and other simple complex number theory formulas The Attempt at a Solution I'm having troubles understanding the format, which...

Hi I found these two definitions of duty cycle: 1: The duty cycle of a machine refers to how long it can keep operating before it needs a rest, or what percentage of the time it's designed to be in use. For instance, a machine gun might only be able to fire continuously for 100 rounds...

hello to everyone, I have a problem solving a stochastic differential equation of the form: dX/dt=aX²+bX+c+sXn(t), where n(t) is white noise with a mean value equal to 0 and variance equal to one. Does anyone know the solution of this stochastic differential equation or how to solve...

Say you have exp{(\omega)} and \omega has a simple pole show that exp{(\omega)}=exp{(F+)}z^{-1}exp{(F-)} where F+ is holomorphic and F- is antiholomorphic. My basic thought is if \omega has a simple pole then \omega z is holomorphic and on the punctured disk it can be represented by a Laurant...

Dear Forum Is anyone using FEniCS to perform finite-element method calculations? I want to work myself into PDE's and I found this Python based software. After installation, I tried to run the example, but I get the following error: I installed the FEniCS binary on my MacBook Pro running under...

Hi, Ho do I calculate for the curve line in this graph I understand that I use this equation v = d/t.Could anyone show me an example?

Hi, I've these values: # x y=f(x) 50 1957768251 100 3915542997 150 5873311096 500 19577709464 1000 39155455160 1500 58686574963 2000 78292255800 2500 97888617384 3000 117466340329 3500 137044056081 4000 156491263529 4500 176177759312 These values...

Homework Statement My dad is driving coal. His truck has a limited coal-capacity, and enough fuel. He drives this coal from the central which has enough coal, to farmers that need different amounts. As there are many farmers, he has to drive back and forth several times. He knows all...

Hi there, I time (seconds) and speed data for a journey in a car. I looking to get the jerk profile of the car. Jerk can be derived by taking the second derivative of the speed. Can some please show me an example of how to calculate it. Thank you Some sample data is time speed 1...

Can someone give me an example of a case where kinetic force would be greater than static force? Thanks.

Hi! I started to look into freq response analysis of a cantilever beam using COMSOL. Luckily COMSOL already has an example model "Model Library>> Structural mechanics module>>Dynamics and Vibrations>>rotating blade". While not changing anything in the model and with Omega=0 and Cloris =0, I get...

Given a differential equation dy/dt = F(t,y), can anyone give me an example that shows no solution exists if F(t,y) is discontinuous? Thanks

Hi, Does anyone know a fluid with low compressibility? Thanks, H

Hello everybody. I have the following problem: I am given a Speed distribution function, f(v). This distribution is normalized to the total number of particles there are, that's equivalent to: \int_0^\infty f(v) dv = n_0 (particles traveling away from my target are not considered.)Now. I know...

Homework Statement if (an) and (bn) are bounded positive sequences prove that limsup(anbn)<= limsup(an)limsup(bn) and give an example to show there is not equality in general

For any natural number a and b, with b > 1, two natural numbers x and y can always be found such that b^x - b^y is divisible by a. Until now, with many tries of a and b, I have always found corresponding x and y. I would appreciate if somebody could give me a proof or a counter example.

Homework Statement A continuous function g: Q --> R such that g(0)=0 and g(1)=1, but there does not exist any x in Q such that g(x)=1/2Homework Equations Number sets, basic number theory The Attempt at a Solution The function could be f(x) = x^2 since f(0) = 0 f(1) = 1 f(x) = 1/2 here it...

Homework Statement A differentiable function g: R --> R such that f' is unbounded on any interval of length one Homework Equations The Attempt at a Solution It's probably easiest to look at [0,1]...maybe something that goes to infinity as it approaches 1? But not sure if it would...

Homework Statement A continuous function g: Q x Q --> R such that g(0,0)=0 and g(1,1)=1, but there does not exist any x,y\in Q such that g(x,y)=1/2Homework Equations Mean value theorem?The Attempt at a Solution I want to say no, because I'm sure there's something going on because the domain is...

Homework Statement A sequence of Lipschitz functions f_n: [0,1] --> R which converges uniformly to a non-Lipschitz function Homework Equations a function f: A --> R is Lipschitz if there exists a constant M \in R such that |f(x)-f(y)|<=M|x-y| The Attempt at a Solution I don't think...

Give an example to show that if not assuming independence of X1, X2, ..., Xn it is possible to show that Var(1/n * sum from k = 1 to n of Xk) >> \sigma^2/n

Anyone know of an example of an algebra over the field \mathbb{Z}_2 with the following properties? 1. commutative; 2. associative; 3. x^3 = 0 , for all x; and 4. Exists x and y such that x^2y \neq 0 . Grateful!

Homework Statement How to represent function \frac{1}{e^x-x-1} in form of Laurent series around point 0 Homework Equations Laurent series f(z)=\sum^{\infty}_{n=-\infty}a_n(z-z_0)^n Here is z_0=0 The Attempt at a Solution Computer gives \frac{2}{x^2}-\frac{2}{3...

Hi, I'm trying to understand the natural transformation from V to V**, and the book has the theory but I think I'm needing an example. Lets say V=R^2 a vector space over K=R. B={(1,1),(1,-1)} a basis of V B={x/2 + y/2, x/2 - y/2} a basis of V* v = (3,2) a vector of V I want to get a...

Homework Statement A well insulated container of negligible thermal capacity contains 30 kg of water at 90oc. A mixing process then takes place in which 50 kg of liquid water at 17oc is added to the tank. The mixing process is continued until thermal equilibrium is established...

Homework Statement A two-dimensional incompressible flow takes place in the space between two parallel solid plane boundaries, which are a distance 2b apart. The density of the fluid is p, the dynamic viscosity is p. and the velocity distribution in the flow is given by the expression I...

So the general tactic for straight lines: f(x) = 2x Show by epsilon-delta definition of limit, as lim x->2, f(x) tends to 4. let, ε>0, and choose 0<δ<ε/2 (|x - 2|<δ)→ |f(x) - 4| = |2x - 4| = 2|x - 2| < 2δ < ε No problem, but what about for a parabola? g(x) = ax2 for some a in R. Show as lim x...

Attached is a worked problem in the Classical Mech book by Morin. I don't understand how eqn (2.57) is the net moment about the pivot. Isn't it only the moment of the weight of the portion of the stick to the right of the pivot ? What about the moment due to the weight of length 'l' on left...

Spivak: Calculus on Manifolds, p. 42: Assuming "differentiating f(x,g(x)) = 0" means differentiating f \circ h, where h : (-1,1) \rightarrow \mathbb{R}^2 \; | \; x \mapsto (I(x),g(x)), I(x) = x and setting the result identically equal to zero, we have 2x+2g(x) \cdot g'(x) = 0, as...

Homework Statement A function f: R -> R such that f is continuous at a point c if and only if c is not an element of the set: { m\2^n: m,n in Z, n>=0) Homework Equations Definition of continuity/discontinuity? The Attempt at a Solution Is it enough to say that we can define a...

Homework Statement An open set A contained in R (reals) such that the closure of A = R, but R \ A is uncountable Homework Equations I guess knowing that for the closure of a set A to be equal to R means that A is dense in R? The Attempt at a Solution Every thing I try seems to...

Hello, I found http://omlc.ogi.edu/classroom/ece532/class1/radiance_flashlight.html" an example of calculation of radiance. I found this example quite confusing, and now I am not sure whether it's me who didn't understand some concepts, or the author who silently made a bunch of simplifying...

Hi, Can somebody give me an example of a rank 4 tensor in physics? Thanks.

I’m studying GR and am curious about manifold, atlas and charts. I have an idea for building a simple example, in one dimension, and wanted to ask if what I’m doing below is “legal”/correct. Imagine a space flight that can be divided into three segments: A-B: velocity starts at zero and...

This is an example shown in "Introduction to Electrodynamics" by Griffiths. Page 226 example 5.8. Given a sheet of current K on the xy-plane where current traveling in +ve x direction. Find the magnetic field. I am confused on the way the book justify the z direction of B is zero. The...

Homework Statement In Example 3 under Theorem 2.5 of Apostol's Calculus Volume 1, I don't understand how the final formula on the right is obtained.Homework Equations The identity cos 2x = 1 - 2 sin2 x implies sin2x = 1/2(1 - cos 2x) so, from Example 2, we obtain: \int^a_0\,sin^2\,x\,dx =...