Term Definition and 775 Threads

Homework Statement Consider a point mass m attached to a string of slowly increasing length ##l(t)##. Them motion is confined to a plane. Find L and H. Is H conserved? Is H equal to the total energy? Is the total energy conserved? Assume ##|\dot{l}/l|<<\omega## Homework EquationsThe Attempt at...

This is my first post on this forum so sry if this is in the wrong place, but also it’s a weird question so I don’t know where it falls exactly. Anyways my question is: when you have an angle, the further the distance is from the point where the angle forms, the distance between the two inner...

Hi all, I have the code below with a 'for' loop. I see the output is 17, the sum of all elements of the (variable?) result. I am a bit confused: I cannot tell which part of the code is used to determine that the values {1,2,10,4,5} must be added to each other? Please comment/correct: 1)We define...

Hi everybody ! In one of my papers I need to add Gibbons-Hawking-York boundary term in order to calculate everything properly. I found a paper (https://www.sciencedirect.com/science/article/pii/S0370269316306530 ) in which authors included this term into the action. My problem is: I tried to...

Homework Statement Considering the molecule of ##C_2^+## in an excited state with valence configuration ##2\sigma_g^2## ##2\sigma_u^2## ##1\pi_u^2## ##3\sigma_g^1##. Finding all the possible term symbol. Homework Equations Term symbol ##^{2S+1}\Lambda## ##L=0 \rightarrow \Sigma## ##L=1...

For a DEQ like this: y = y( x ) a y'''' + b y''' + c y'' + d y' + f y = g( x ) where a, b, c, d, f are constants. I would think it would be called a "constant coefficient DEQ", but a DEQ like this would also be called this a y y'' + b ( y' )2 = g( x ) but I am only interested in...

Dear All Please could you kindly help? I am new to this forum, kindly excuse me for asking. The nth term for the following set of numbers is required. If someone could please guide me, I would be grateful. Thank you. Suggestion to solve the nth term suggestion for the following list please...

I learn quantum field theory using the book of " quantum field theory in a nutshell" by A. Zee. But I am confuse when I read the content about the "baby problem" at the beginning of "1.7 Feynman Diagrams". In that section, author get the term of order λ and [J][/4] by -(λ/4!)[(d/dJ)][/4]...

Given that the sum of the first n terms of series, s, is 9-3^2-n (i) find the nth term of s. Do I have to use the formula sn = a(1-r)/1-r?

Hello Friends! Which company do you recommend for a solid hands on short term training(1-5 weeks) in Europe/Asia for electrical engineers? I wish to get a solid training in one of the following areas: 1- Industrial control system and automation 2- Building installation (data + power) 3-...

A geometric sequence has an initial value of 25 and a common ratio of 1.8. Write a function to represent this sequence . Find the 23rd term. My Effort: The needed function is a_n = a_1•r^(n-1), n is the 23rd term, r is the common ratio and a_1 is the initial value. a_23 = 25•(1.8)^(23 - 1)...

I'm trying to show that the theta term in the QCD Lagrangian, ##\alpha G^a_{\mu\nu} \widetilde{G^a_{\mu\nu}}##, can be written as a total derivative, where ##\begin{equation} G^a_{\mu\nu} = \partial_{\mu} G^a_{\nu} - \partial_{\nu}G^a_{\mu}-gf_{bca}G^b_{\mu}G^c_{\nu} \end{equation} ##...

Homework Statement [/B] I have the following expression: $$S=T+V$$ $$T=\frac{m}{\tau_0+it}((x_1-x_0)^2+(x_2-x_1)^2)+\frac{m}{2(\tau_1-it)}(x_2-x_0)^2$$ $$V= \frac{(\tau_0+it)}{2}(\frac{k_0 x_0}{2}+\frac{k_0 x_2}{2}+k_0 x_1)+(\tau_1-it)(\frac{k_1 x_0}{2}+\frac{k_1 x_2}{2})$$ The main goal...

I thought my algebra skills were good, but this problem has me frustrated. I would like to rearrange the equation to solve for Ru, but I can't seem to get Ru isolated. All values are known except for Ru. V/(Vin*R)=(1/(R+Ru*k))-(1/(R+Ru))Thank you in advance.

Homework Statement Test the series for convergence or divergence ##1/2^2-1/3^2+1/2^3-1/3^3+1/2^4-1/3^4+...## Homework Equations rn=abs(an+1/an) The Attempt at a Solution With some effort I was able to figure out the 'n' th tern of the series an = \begin{cases} 2^{-(0.5n+1.5)} & \text{if } n...

This problem is about one small step in the derivation of Maxwell's equations in free space from the field Lagrangian. The Lagrangian contains a term proportional to ##\partial \mu A_\nu \partial^\mu A^\nu - \partial \nu A\mu \partial ^\mu A^\nu## where A is the four-vector potential. The...

So the first term of the Lagrangian is proportional to ##{F_{\mu \nu}}{F^{\mu \nu}}##. I wrote out the matrices for ##{F_{\mu \nu}}## and ##{F^{\mu \nu}}## and multiplied at the terms together and added them up, but some of the terms didn't cancel like they should have. Should I have used minus...

I understand that the terms "differentiation" and "epigenetic" apply to cells in multicellular environment, and that different DNA is expressed to create distinct features in different cells. What about the process of the creation of distinct features within the cell itself, such as all the...

What is the name given to the path along which a free north pole end of a magnet would point? Name of a "path"? The name is magnetic field line? north pole?

I have a very simple question. Let's consider the theta term of Lagrangian: $$L = \theta \frac{g^2}{32 \pi^2} G_{\mu \nu}^a \tilde{G}^{a, \mu \nu}$$ Investigate parity of this term: $$P(G_{\mu \nu}^a)=+G_{\mu \nu}^a$$ $$P( \tilde{G}^{a, \mu \nu} ) =-G_{\mu \nu}^a$$ It is obvious. But what about...

Hi, did the energy of the universe, right before big bang equal to zero? And if so, does zero as zero-point energy in relativistic theory and quantum mechanics make any sense? If this is not possible, are there any models, including the standard model, SUSY or QFT which consider ground state...

I have a question about work. If Newtons 3rd law of motion states there is an equal and opposite reaction for any force. Now if for example I apply 500 Newtons of force on my dresser and move it 5 meters I used 2500 joules of energy. Now because the dresser is equally putting that much force...

Homework Statement I am going through a derivation of the thermal energy equation for a fluid and am stumped on one of the steps. Specifically, the text I am using converts the term: P/ρ*(Dρ/Dt) to: ρ*D/Dt(P/ρ) - DP/Dt where: ρ = density P = pressure D/Dt = material derivative The text...

Hello every one, End of terms papers always are weird and non natural for me. This is a senior class about solid state physics and we are asked to write a 5-10 pgs term paper on a certain topic. My question is how do you go about formatting this kind of paper? Abstract(??) ->...

Consider a free real scalar field. The quadratic term in field of spacetime implies that a universe of these free particles is created, annihilated, recreated, and so on moment by moment. In this video Susskind explains the quadratic term in the Lagrangian youtu.be/D7yXoNAg3J8 (At minute...

Hi all, I am reading Bernard Schutz's a first course in general relativity. In Chapter 4 it introduced the energy stress tensor in two ways: 1.) Dust grain 2.) Perfect fluid. The book defined the energy stress tensor for dust grain to be ## p⊗N ##, where ##p## is the 4 momentum for a single...

The molecules that replicate DNA are collectively called "replisome". Is there a similar term for all the molecules that synthesize proteins (both through translation and transcription)? Short of, of course, "protein synthesizers". I can't seem to find the term, any feedback appreciated!

i thought of an example of a 2 system that would give anti torques for each other but i want to know how to properly calculate it and if there is a term for that kind of example: two manual treadmills placed infront of each other without any handles so nothing to grab on to. and for the...

Once I had stored Petrol (Gasoline) in a airtight 1 liter plastic container for 6-8 months. When I opened the container, Gasoline had become a thick brown gel. Is it reusable ? Is it still Gasoline or it has become something else ? Thx

If $$\phi(t,x)$$ is a solution to the one dimensional wave equation and if the initial conditions $$\phi(0,x) , \phi_t(0,x)$$ are given, D'Alembert's Formula gives $$\phi(t,x)= \frac 12[ \phi(0,x-ct)+ \phi(0,x+ct) ]+ \frac1{2c} \int_{x-ct}^{x+ct} \phi_t(0,y)dy . \tag{1}$$ which is...

##\displaystyle f_{n} = ((\sum_{k= \lfloor{\frac{n}{2}}\rfloor}^{n-1}f_{k}) mod 1) + 0.1## ##\displaystyle f_{1} = 0## I really would like to know where to begin for finding a formula for the nth term, I wrote out a bunch of the terms and couldn't really eyeball a pattern of any sort. I noticed...

Homework Statement This was a problem on my fluids final and I'm trying to figure out if my rationale was correct here. The problem was an open air tank filled with water and at the bottom was a pipe pointing straight down. You had to find the exit velocity at the bottom of the pipe and account...

Homework Statement I am trying to fill in the steps between equations in the derivation of the coordinate representation of the Darwin term of the Dirac Hamiltonian in the Hydrogen Fine Structure section in Shankar's Principles of Quantum Mechanics. $$ H_D=\frac{1}{8 m^2...

Is there a radiometric term for the quantity (power emitted per unit volume per unit solid angle)?

What is the procedure for finding the unknown term(end value in this scenario) in a series? For example \sum_{r=1}^{n}{2r+3} My Attempt was to simply state the first four terms and then simply add the nth term as it is: 2(1)+3=5 2(2)+3=7 2(3)+3=9 2(4)+3=11 2(n)+3=2n+3...

We can ignore the boundary contribution, namely the term that arises when we solve $$\int d^{4}x \sqrt{-g}g^{ab} \delta R_{ab}$$ when varying the action. According to Wikipedia it's appropriate to do so only when the underlying manifold is both without boundary and compact. That condition seems...

In field theory a typical Lagrangian (density) for a "free (scalar) field" ##\phi(x)## is of the form $$\mathcal{L}=\frac{1}{2}\partial_{\mu}\phi\partial^{\mu}\phi -\frac{1}{2}m^{2}\phi^{2}$$ where ##m## is a parameter that we identify with the mass of the field ##\phi(x)##. My question is...

Homework Statement A simple harmonic oscillator has a potential energy V=1/2 kx^2. An additional potential term V = ax is added then, a) It is SHM with decreased frequency around a shifted equilibrium b) Motion is no longer SHM c)It is SHM with decreased frequency around a shifted equilibrium...

Suppose I heat a room directly by lighting a fire in the room, let's say it is a butane gas fire and it takes n BTU to raise the temperature by 10°C. Now, suppose I don't like the smell of burning gas fumes and decide instead to move the same gas fire outside and boil water to generate steam...

Homework Statement I(λ, T) is 4 pieces multiplied: (8π/λ4) (hc/λ) (1/(ehc/λkT-1) (c/4). 1. Identify the meaning of each term. 2. Which term(s) fix the ultraviolet catastrophe? The Attempt at a Solution Well I know that the energy of a photon is given by (hc/λ), and I'm fairly certain it was...

Homework Statement Please see the attached,this was extracted from my notes.(Left side is the 1st page).I was trying to prove the sentence underlined (on the right page). Given ε(r,t) , how can I prove that the cross-terms average to 0? Actually I don't really understand why there are...

The Genkin-Mednis is usually used to calculate the nonlinear optical properties of periodic polymers or crystals, the analytical derivation is captured in the posted image, My problem is (483), where does an extra term on the right hand side of (483) come from? ie S^\dagger (\kappa...

I know that the generalization of parallel lines to curves in 2D is just "parallel curves", but is there any term which generalizes the idea of skew lines to curves? "Skew curves" doesn't work, this term already being co-opted by statistics. Example: if you had two curves coiling around each...

I was reading some articles related to entropy and I come to know that, The term “Entropy” shows up both in thermodynamics and information theory. Now my question is : What’s the relationship between entropy in the information-theory sense and the thermodynamics sense? I need some clear and...

It has occurred to me since May 2015 that for certain purposes the matter term in the Friedman equation might benefit from a modification. https://www.physicsforums.com/threads/how-does-a-particles-kinetic-energy-vary-with-a-t.811627 The Friedmann equation shows the matter term to be based on...

Homework Statement I just want to know how get from ##4x^3+3x^2-6x-5=0 ## to ##(x+1)^2(4x-5)=0##. What's the trick when dealing with these nasty polynomials? I got the answer by taking another approach (solving a root equation) but I noted this is also a way to go, but I can't figure out the...

Hi, My question is that can one interaction term represent two vertices? For instance, can the lagrangian interaction terms L = eψγμψAμ represent a feynman diagram like these: or should there be two terms in the lagrangian to construct such diagrams? Thanks!

For graduate school admissions? I will finish my third year this April and then will start an 8 month full time research project. I will have the possibility to graduate with 7 semesters instead of 8, but if I apply to graduate schools next December I will not have any first term grades. Would...

Homework Statement Fourier series expansion of a signal f(t) is given as f(t) = summation (n = -inf to n = +inf) [3/(4+(3n pi)2) ) * e j pi n t A term in expansion is A0cos(6 pi ) find the value of A0 Repeat above question for A0 sin (6 pi t) Homework Equations Fourier expansion is summation...

Homework Statement The coefficient of the term (x−π)2 in the Taylor expansion for f(x)=cos(x) about x=π is: Homework Equations ##cos(x) = 1 - \frac{x^2}{2!} + \frac{x^4}{4!} - \frac{x^6}{6!} + \frac{x^8}{8!}...## The Attempt at a Solution Unless my taylor series for cosine is incorrect, I'm...