Example Definition and 879 Threads

What does it mean to treat something as a point mass. Give an example as well. Thank you.

Homework Statement Here's a standard example of special relativity in action: The mean lifetime of the muon as measured in a laboratory is about 2µs (rounded to 1 s.f.). Thus, the typical distance traveled by a muon should be about ##3\times 10^8ms^{-1}\times 2\times 10^6s = 600m##. The...

I don't have much spear time at the moment, but I came across a SMPS diagram in this thread: https://www.physicsforums.com/threads/quick-question-about-inverter-tx-order-wrt-mains.870309/ And I was trying to figure it out, and I don't want to forget about it before I do. So I was wondering if...

Homework Statement Homework Equations A=epsilon*l*c The Attempt at a Solution So I was wondering on how to set up the equations now, since I don't have much information? Which equations should i use to solve the problem?

Hello all. In Morin's classical mechanics book, chapter 12 (relativistic dynamics), in the axample about the relativistic rocket, we have a rocket that propels itself converting mass into photons and firing them back. Here Morin takes dm as a negative quantity, so the instantaneous mass of the...

The normal subgroup of a normal subgroup need not be normal in the original group (normalcy is not transitive). Could somebody provide me with an example of where this is the case? Thanks :D

I am reading Paolo Aluffi's book: Algebra: Chapter 0 ... ... I am currently focussed on Section I.3 Categories ... ... and am trying to understand Example 3.8 which is introduced as a concrete instance of the coslice categories referred to in Example 3.7 ... Examples 3.7 and 3.8 read as...

I am reading Paolo Aluffi's book: Algebra: Chapter 0 ... ... I am currently focussed on Section I.3 Categories ... ... and am trying to understand Example 3.8 which is introduced as a concrete instance of the coslice categories referred to in Example 3.7 ... Examples 3.7 and 3.8 read as...

Homework Statement A simple classical example that demonstrates spontaneous symmetry breaking is described by the Lagrangian for a scalar with a negative mass term: ##\mathcal{L}=-\frac{1}{2}\phi\Box\phi + \frac{1}{2}m^{2}\phi^{2}-\frac{\lambda}{4!}\phi^{4}##. (a) How many constants ##c##...

Hello I have to search for a few solved examples in fortran and understand them so next week i can make a presentation and explain into the other students. It is a homework for everyone and i don't know which programm i should use. there are few homepages which have many examples but they are...

I am reading Bruce N. Coopersteins book: Advanced Linear Algebra (Second Edition) ... ... I am focused on Section 10.3 The Tensor Algebra ... ... I need help in order to get a basic understanding of Example 10.1 in Section 10.3 ...Example 10.1 plus some preliminary definitions reads as...

I am reading Bruce N. Coopersteins book: Advanced Linear Algebra (Second Edition) ... ... I am focused on Section 10.3 The Tensor Algebra ... ... I need help in order to get a basic understanding of Example 10.1 in Section 10.3 ...Example 10.1 plus some preliminary definitions reads as...

whu at w=100 the effect of c0 and c2 will not count also w=200 the effect of c1 and c0 will not count?

What is an example of a rigid body rotating when one point is fixed and there are no net applied torques? And the fixed point is not the center of mass. I considered a cone rolling without slipping on a flat plane is such an example; the apex is the fixed point, but is there a net applied...

Homework Statement I have a test coming up in projectile motion, and I understand very little of it. Like calculating hang time, horizontal range, max height etc. Homework Equations ΔY=vyiΔt+1/2ay(Δt)^2 Quadratic formula There shouldn't be any math past Algebra I The Attempt at a Solution

Hi every body I study transversal submanifolds,I have an example but I didn't find some quatities. In Rn+p we consider the submanifold N=Rn+1, we know that P is tottaly geodesic and another manifolds M which is the sphere of dimension n+1 of radius r and centrer p0. then the transversal...

Homework Statement Could someone give an example question in De Donder-Weyl theory (the multisymplectic theory where the hamiltonian is not parametrized by time, it's on wikipedia). Homework Equations The relevant equations should not be too complicated, just complicated enough to use the...

Can anyone show me an example of applying the Ricci curvature tensor to something other than GR? I also ask the same for the curvature scalar. Lately I've been trying to truly increase my understanding of curvature, so that I can see exactly how solutions of the EFE's predict the existence and...

I am reading Andrew McInerney's book: First Steps in Differential Geometry: Riemannian, Contact, Symplectic ... I am currently focussed on Chapter 3: Advanced Calculus ... and in particular I am studying Section 3.3 Geometric Sets and Subspaces of T_p ( \mathbb{R}^n ) ... I need help with a...

Good day to you all, I could be asking too much here. I’m someone who prefers to understand formulas by deriving them from own made scenarios. In this case I was trying to derive the time dilation Lorentz formula using my own made up example and I wanted to know if I'm on the right track here...

Currently working through a chapter on op amp circuits, fundamentals. Came upon this practice problem in the section on inverting op amps imgur link: http://i.imgur.com/2DrQLXk.png imgur link: http://i.imgur.com/7KRKzKC.png A working of this problem is not given. I got the correct answer...

1. The problem statement Hi, I just have a quick question on how to find the normal force in this picture on mass 2, http://postimg.org/image/w9sr29ab3/ , the half circle. Its a double pendulum with no friction. Can I assume that the normal force is in that position all the time as the half...

This is it; most likely the last time I bother the people of this website with my questions on traffic flow. I'm trying to figure out some concrete examples to demonstrate utilization of the conservation equation in traffic flow: \frac{\partial \rho }{\partial t} + \frac{\partial q(\rho...

I am reading Andrew McInerney's book: First Steps in Differential Geometry: Riemannian, Contact, Symplectic ... I am currently focussed on Chapter 2: Linear Algebra Essentials ... and in particular I am studying Section 2.6 Constructing Linear Transformations ... I need help with a basic...

https://www.physicsforums.com/attachments/5246 I'm trying to follow this example but where does the $\frac{1} {2 } $ come from in step 3

I'm looking for good examples of physical motivation for integrals over scalar field. Here is an example I've found: If you want to know the final temperature of an object that travels through a medium described with a temperature field then you'll need a line integral It appears to me that...

Homework Statement [/B] Hey, all. I am working through Kleppner/Kolenkow and encountered a problem when trying to follow the example pictured below. My issues comes when they say "Equations (1)-(3) are easily solved..." As it turns out, they are not so easily solved for me! So, it appears I've...

I am reading Barrett O'Neil's book: Elementary Differential Geometry ... I need help with some more issues/problems with the example on wedge products of differential forms in O'Neill's text on page 31 in Section 1.6 ..The example reads as follows: In my working of the example above ... trying...

I am reading Barrett O'Neil's book: Elementary Differential Geometry ... I need help with fully understanding the example on wedge products of differential forms in O'Neill's text on page 31 in Section 1.6 ..The example reads as follows: I do not follow the computations in this example ... can...

Hey! :o Could you give me a hint how we can find the Cayley table of a groupoid? For example for the groupoid $(2^{\{a,b\}},\setminus )\times (\{0,1\},\min )$. (Wondering) ( $\setminus$ means the set difference )

Show that the 3-D FT of a radially symmetric function may be rewritten as a Fourier sin transform i.e. $ \frac{1}{({2\pi})^{{3}_{2}}} \int_{-\infty}^{\infty}f(r)e^{ik \cdot r} \,d^3x = \frac{1}{k} \sqrt{\frac{2}{\pi}} \int_{-\infty}^{\infty} \left[ rf(r) \right] sin(kr) \,dr $ The example...

Homework Statement [/B] I had 3 wt % starch concentration in 230 gram of water. During the experiment 100 gram of water was evaporated and gone. Therefore, 130 gram of solution was remained. What is the wt% concentration of the starch after water evaporation? Is my calculation sounds correct...

I am reading An Introduction to Rings and Modules With K-Theory in View by A.J. Berrick and M.E. Keating (B&K). I need help in order to fully understand Example 1.2.2 (iv) [page 16] ... indeed, I am somewhat overwhelmed by this construction ... ... Example 1.2.2 (iv) reads as follows:My...

On pages 67 & 68 of Hassani's mathematical physics book, he gives the following definition: "Let ## \mathcal{A} ## and ## \mathcal{B} ## be algebras. The the vector space tensor product ## \mathcal{A} \otimes \mathcal{B} ## becomes an algebra tensor product if we define the product ##...

Homework Statement Hi this isn't really a question but more so understanding an example that was given to me that I not know how it came to it's conclusion. This is a question pertaining linear transformation for coordinate isomorphism between basis. https://imgur.com/a/UwuACHomework Equations...

I know the method and can solve other initial value problems. This is the question given: dy/dx + y(-2) Sin(3x) = 0 for t > 0, with y(0) = 2. I've brought the dy/dx and let it equal to the rest of the expression so it is now: dy/dx = -y-2 Sin(3x) , with y(0) = 2 (i.e. when x = 0, y = 2 ) The...

Homework Statement The statement of the question is:A chain of uniform linear mass density ##\rho##, length ##b## and mass ##M## hands as shown in the figure below. At time t=0, the ends A and B are adjacent, but end B is released. Find the tension in the chain at point A after end B has...

In section 3.5 of his textbook Quantum Field Theory, Ryder discusses an example of a non-Abelian gauge theory. He considers a 3D internal space and rotations in this space. At first he shows that the fields in this internal space transform like ##\delta \vec \phi=-\vec \Lambda \times \vec \phi...

Hi, I don't get the right answer for this question. I don't see where I'm going wrong. I use this equation to get the engine rpm for each gear ratio: engine speed (rpm) = gear ratio X final drive ratio X vehicle speed X 60 / (2*pi*rolling radius) So for first gear I get an engine rpm of...

I am reading an article by Tachikawa on the Nekrasov partition function ("A review on instanton counting and W-algebras"). The article is meant to be pedagogical but I have some trouble with what is supposed to be "baby" examples. The first one involves susy QM on \mathbb{C}^2 . He says the...

According to A Borobantu, regarding superposition, where Ψ is a state vector or a wave amplitude, given Ψ1, Ψ3, Ψ3... Ψncan by physically realized, then the following statement holds for all linear combinations Ψ = ∑ciΨi where ci can satisfy 1 = ∑|ck|2 to be called a complete and closed...

Here is my task (Basics of analogue telecommunications): Block diagram of device for simultaneous transfer of two telegraphic signals u1(t) and u2(t) is shown on image 1. Both signals have waveform as periodioc signal um(t) on image 2. Frequencies f1 and f2 of carriers $$u_{01}(t)=U_0...

Hi, I know that changes in entropy can be expressed as a function of temperature, specific volume, and pressure using the fundamental equations of thermodynamics: ds = du/T+pdv/T, where the changes in entropy can be caused by either changing the specific volume or the internal energy. I also...

Suppose ## V ## is a vector space and ## W ## is a subspace of ## V ##. Then for ## |a\rangle, |b\rangle \in V ##, say that ## |a\rangle ## and ## |b\rangle ## are equivalent (in the sense of an equivalence relation), if ## |a\rangle - |b\rangle \in W ##. Denote the equivalence class of ##...

Reading Geroch's "What is a Singularity in General Relativity?", it seems that polynomial scalar invariants constructed from the Riemann tensor can diverge if we are at infinite distance, and not in a true singularity. Can someone give an example of space-time whose scalar invariant diverges...

Hi, I've never studied compex analysis before but I am trying to understand this example from "QFT for the gifted amatur". I don't understand why the residue at the pole is e-iEp(t-t')e-e(t-t'). How did the find e-e(t-t')? Thanks.

In Bruce Cooperstein's book: Advanced Linear Algebra, he gives the following example on page 12 in his chapter on vector spaces (Chapter 1) ... ...I am finding it difficult to fully understand this example ... ... Can someone give an example using Cooperstein's construction ... using, for...

Homework Statement This isn't actually a homework question.Actually, it's an example from Rosen's Discrete Math and Its Applications that I'm having difficulty with: "A computer system considers a string of decimal digits a valid codeword if it contains an even number of 0 digits. For...

is This example correct? I made it up Twin Z get close to a black hole to observe it (theoretically he is Not in orbit, Not moving but close in off to an black hole to be affect by the gravity of it, and the black is not moving in space or rotating) And Twin X stay behind on the mothership...

I would like to hear different examples of presenting the difference that general theory of relativity relates between a stretched piece of spacetime around a planet and a not stretched one far away from any kind of mass or energy distortions...these examples i would like to be written in a...