Periodic Definition and 411 Threads

Hi there, why the decomposition of periodic Composite signal give discrete frequencies and decomposition of aperiodic signal give continuous(in decimal) frequencies. please kindly do explain the concept behind in as simple words possible. Thanks

My book says this: I don't understand how this works. I learned that the usual sunisoidal function looks like sin(wt+phi), where w is frequency, t is time, and phi is some offset. EQ 17.1 doesn't match the bolded formula above. How does this work?

Hi. Why do some countries use different names for the elements instead of their original names as indicated by their symbol? Like Na(natriu) is called sodium, Au(aur) is gold, Fe(fier) is iron, Cu(cupru) is copper, Ag(argint) is silver, Pb(plumb) is lead. I'm from a Latin/francophone country and...

Amoung three elements F,CL,Br which is more reactive? I guessed it to be bromine because it has three shells and hence when we go down the group on the basis of their shells bromine will easily lose electrons. But the book says it is fluorine since it can easily gain electrons.And how can that...

Homework Statement (i) An element that has a molecule which contains exactly four atoms. (ii) An element that reacts with water to give a solution that can behave as an oxidising agent. Homework EquationsThe Attempt at a Solution (i) Shouldn't it be boron? Boron forms BF3 which has four...

http://www.iupac.org/news/news-detail/article/discovery-and-assignment-of-elements-with-atomic-numbers-113-115-117-and-118.html

Homework Statement Periodic function P=3 f(t) = 0 if 0<t<1 1 if 1<t<2 0 if 2<t<3 a) Draw the graph of the function in the interval of [-3,6] b) Calculate the Fourier series of f(x) by calculating the coefficient. Homework EquationsThe Attempt at a Solution a) in attached...

Hey guys we say that when in periodic table we go from left to right atomic size decreases because of increase in nuclear charge in the same shell but my question is that the electron to proton ratio is 1:1 then how nuclear charge is increased. Some say nuclear charge is concentrated but my...

[SIZE=14px][FONT=Verdana]We know that periodic function can be written in terms of complex Fourier coefficients: $$f(t)=Fn0+\sum_{n=-\infty,n\neq 0}^{n=\infty}F_ne^{jnw_0t}$$, where $$Fn=\frac{1}{T}\int_{\tau}^{\tau+T}f(t)e^{-jnw_0t}dt$$ and $$Fn0$$ is DC component. Power spectrum of signal is...

Homework Statement Please see the attached.I don't know how to do (ai). potential function is the potential energy defined by f = -dV/dx e is the total energy of the system where e = KE + PE = (dx/dt)^2 /2 + V Note:m=1 because the particle has a unit mass If you integrate f,you get V(the...

I know the equation for damped oscillation where the damping force depends on velocity. In that case the damped oscillation has a fixed angular frequency and thus time period! I am wondering if there are any types of damped oscillation where the time period is not constant i.e. the motion is not...

A Bloch wave has the following form.. ## \Psi_{nk}(r)=e^{ik\cdot r}u_{nk}(r)## The ##u_{nk}## part is said to be periodic in real space. But what about reciprocal space? I've had a hard time finding a direct answer to this question, but I seem to remember reading somewhere that the entire...

Hello! (Wave) Periodic problem We are looking for a periodic function $u \in C^2(\mathbb{R})$ with period $(b-a)$ $$-u''+qu=f \text{ where } q,f \text{ periodic functions with period } (b-a) \\ u(a)=u(b) \\ u(x)=u(x+(b-a))$$ $x_i=a+ih \\ h=\frac{b-a}{N+1}$ $\mathbb{R}_{\text{per}}^{N+1}=\{...

Homework Statement A pendulum with a mass of 0.1 kg was released. The string made an angle of 7 ° with the vertical. The bob of the pendulum returns to its lowest point every 0.1 seconds. What is the period, frequency? Homework Equations T= 1/f T=sec/cycles F= cycles/sec The Attempt at a...

Prove f(x) = sin(x^2) isn't periodic. f is periodic if f(x + t) = f(x) for all x in f's domain. I know about 1 way of proving it by derivative and boundedness but is this another way? If f is periodic then sin(x^2) = sin((x + t)^2) Finding t: (I don't know the proper way of doing this, maybe...

I'm sorry for being so vague here, but perhaps my post will ring a bell for someone who can fill in the details. A few weeks ago in a waiting room I was reading about a proposed rearrangement of the Periodic Table based on measurements of the ionization potentials (I think I got that right) of...

Hey. Assume you have a signal ##f## with period ##T_f## and a signal ##g## with period ##T_g##. Then the signal ##h= f+g## is periodic iff ##T_f/T_g \in \mathbb{Q}##. So if ##T_f/T_g## is an irrational number, the signal ##h## will not be periodic. Why is this actually the case?

Hello everyone, I have a question regarding the possible periodicity of time in a generic metric. Suppose that for some reason I have a solution to Einstein's equations of the kind (in Euclidean time): $$ ds^2_E=+f(r)dt_E^2+\frac{dr^2}{g(r)}+r^2(dx^2+dy^2). $$ Am I always allowed to assign...

Hello, I am working on a solo project outside my domain of expertise (Physics PhD student). I am trying to analyze/replicate the wave phenomena shown in the following video: To summarize what I am doing: I need to analyze a simple (cylindrical) pool, say 17.5" wide, 4" deep Figure out how...

I have been looking through the book Counterexamples: From Elementary Calculus to the Beginning of Calculus and became interested in the section on periodic functions. I thought of the following question: Suppose you have a periodic real valued function f(x) with a fundamental period T. Let c...

Homework Statement This problem is not from a textbook, it is something I have been thinking about after watching some lectures on Fourier series, the Fourier transform, and the Laplace transform. Suppose you have a real valued periodic function f with fundamental period R and a real valued...

Homework Statement I hope everyone is having a great day. The equation I am working with at the moment is: (1+ (.2/x))^(x) = 1.21. 1.21 represents the final value, whereas 1 is the present value. I am trying to solve for x, which represents the number of periods necessary for the entity to...

I am trying to set up the mass matrix for a 1D system which I want to solve using finite elements. So the mass matrix is defined as M = \int{NN^T}dL, where N is the finite element linear basis functions. I use hat functions. Say I have 10 elements, corresponding to 11 nodes running from -5...

1. According to physicsclassroom.com, periodic motion is defined as "a motion that is regular and repeating." But the example included does not factor in damping (it's assumed that there's no air resistance and the spring will keep vibrating for eternity.)...

Hi! When we model bloch-waves in a solid we assume that there exist some kind of periodic boundary conditions such that the wave function is periodic. In 1D, ##\psi(x)## repeats itself for every ##L##, ##\psi(x) = \psi(x+L)##, such as here: OK, fine, we get pretty wave solutions if we assume...

I need a link or questions on periodic trends or periodic properties like on atomic radius,ionic radius,ionization energy,electron affinity,electropositivity and electonegativity Thanks Nusaiba mustafa

Greg Bernhardt submitted a new PF Insights post It's Elemental! The Periodic Table Quiz Continue reading the Original PF Insights Post.

I am learning more about the Einstein Filed Equations. I do not know how to evaluate them. Can someone tell me if time can be a periodic function in the equation for spacetime? i may not have that spacetime correctly stated. Can time periodically vary like a SIN function and still work in the...

Let's have a time series with a period=L. Suppose we arbitrarily choose the window length of the trajectory matrix to be equal to L which is also equal to the period of a time series. Then the second column of the matrix will also start with the same entry as the first column, because all...

Homework Statement In the long form of periodic table, the valence shell electronic configuration of 5s2 5p4 corresponds to the element present in A. Group 16 and period 5 B. Group 17 and period 6 C. Group 17 and period 5 D. Group 16 and period 6 Homework Equations NA The Attempt at a...

Homework Statement A block os mass m is attached to a horizontal spring, which is attached to a wall. The block is oscillating without friction with initiation amplitude A0 and maximum velocity v0. When the block is at its maximum amplitude (and therefore instantaneously at rest), is it struck...

Hi, I'm new here. I'm actually studying the periodic table and while collectting the data on excel i noticed something. I wouldn't see it with the usual display of a periodic table but when you put it all in a sheet, ligns after ligns it become obvious to me. Argon Ar (noble gaz) is followed...

There are many different mass numbers for a given element known as isotopes. Are elements on the periodic table isotopes of their element? Why not use the average of all the mass numbers for an element?

Homework Statement The temperature variation at the surface is described by a Fourier series \theta(t)=\sum^\infty_{n=-\infty}\theta_n e^{2\pi i n t /T} find an expression for the complex Fourier series of the temperature at depth d below the surface Homework Equations Solution of the...

Homework Statement Four weightless rods of length ##l## each are connected by hinged joints and form a rhomb (Fig. 48). A hinge A is fixed, and a load is suspended to a hinge C. Hinges D and B are connected by a weightless spring of length ##1.5l## in the undeformed state. In equilibrium, the...

My book is trying to explain why atomic radii decreases as you move toward the right side of the periodic table because the effective nuclear charge increases. I understand why an increase in effective nuclear charge results in a smaller radius, but I don't know why the effective nuclear charge...

Homework Statement Find electrostatic field and potential created by a two-dimensional charge density: \rho \sin (kx) \cos (ky) \delta (z) at the distance d from the the plane z=0 where the charge is placed (taking into account that it is embedded in a three dimensional space). In your...

Dear all, periodic DFT codes (e.g. VASP) effectively simulate an infinite crystal due to the periodic boundary conditions. However, the energy value that one obtaines at the end of a simulation if finite. Frankly, I'm quite confused right now. Is the energy to be understood 'per unit cell'...

Homework Statement Example Question: an electron with mass m is confined in a thin wire, with periodic boundary conditions applied in the x direction and harmonic potentials in the y and z direction. Write an expression for the wave functions in the ground state. Write down all the energy eigen...

Hi ☺️ i have to do a convolution with a periodic signal and a dirac impulse: x(t)=sen(πt)(u(t)−u(t−2)) h(t)=u(t−1)−u(t−3) The first is a periodic graph that intersect axis x in points 0 , 1 and 2 (ecc) The se ing is a rectangle ( Dirac impulse ) that intersect AxiS x in points 1 and 3. For...

What are the most reactive elements in the periodic table?

hello guys .. first of all , iam not sure that i should type this thread here . so excuse me for that in this problem i can understand the part until it's said that w=0 then x(t)=1, which is periodic for any value of T but i can't understand the part after that in the case of w is not equal...

Hi Folks, Prior to leaving my car in for the annual MOT (UK), there were no vibrations to be felt at any speed. However, to pass the MOT I was advised to replace the 2 front tyres as they were worn. Ever since then, there is a periodic vibration which I can distinctly feel at 85mph but it is...

If one simply swings a rope with an object tied to the end of it, the object describes a circle. But if one were to create a contraption that caused the radius of the rope to periodically decrease 4 times every revolution, one could cause the path of the object to describe a square. My...

Hi, I have problems figuring out what both c-coefficients means. Can someone explain this in a conceptual way? Also, Vg and V-g are the coefficients of the Fourier series if you expand V, but what does it mean physically? Thanks in advance.

Is anyone aware of how to numerically solve the (1D) SE with periodic boundary conditions?

For each epsilon greater than 0, show that the differential equation x'=x^2-1-cos(t)-epsilon has at least one periodic solution with 0 less than x(t) less than or equal to (2+epsilon)^1/2

Hi all, I was always of the belief that hydrogen did not belong to any group in the periodic table. After discussions, some say that a group 1 or 7 place might be more suitable. Any opinions would be welcomed hopefully from a physics point-of-view on this topic.Thanks in advance

Hey! :o The Laplace's equation with polar coordinates is: $$u_{rr}+\frac{1}{r} u_r +\frac{1}{r^2} u_{\theta \theta}=0$$ We suppose the boundary value problem with Dirichlet boundary conditions for the Laplace's equation on a disc with center the origin of axis and radius $a$...

Suppose I have a function of the type: h(t) = g(t)f(t) where g(t) is a periodic function. Are there any nice properties relating to the Fourier transform of such a product? Edit: If not then what about if g(t) is taken as the complex exponential?