What is Section: Definition and 733 Discussions

a basic problem but i have no idea how to measure it

Hello. I was hoping someone could help me understand some units. In several papers, I have seen the two photon LIF signal written as: S = n*(Ω/4π)*T*G*σ*(E/hv)^2*η*a where the units are n (density of measured atom): #/cm3 Ω/4π (solid angle fraction): unitless T (optical transmission...

I apologize that this is rather specific, but hopefully enough people have used Goldstein. I have a basic grasp of action-angle variables, and I'm going through the time-independent perturbation theory section in Goldstein (12.4). In this section we seek a transformation from the unperturbed...

Rao: Topology: Proposition 1.2.4. If (X,T) is a topological space, a subset A of X is closed iff the the derived set of A is a subset of A: A'\subseteq A. Rao's proof of (A'\subseteq A) \Rightarrow (X\setminus A \in T) goes like this: To me, this looks like enough to show that...

where can I buy a nuclear power plant section plan? Thank you !

Homework Statement The only given data is that the cross section is 1m^2, the shape is circular (like a cut wire/rod) and i have to find the volume. Homework Equations from what I've searched, i found the equation: but i have no idea what to do with it, i still haven't learned it at...

Homework Statement What is the volume if the area bounded by y=x^2 and y=9 and the cross sections are perpendicular to the y axis Homework Equations The Attempt at a Solution I have no idea

As you all know the NEC code permits only 42 circuits per panel. so what we could do if we need more than 42 circuits ? In order to use more than 42 circuits we can add new section panel. However my question is do we need a separate feeder and breaker for the additional section?

I'm just wondering what the difference is between a cross section and a scattering cross section? Or is there any? I can't seem to find anywhere that clears it up, in fact there's a whole section on scattering cross sections in Kibble and Berkshire but they don't define it once :P

I am reading chapter three of Huang's Statistical Mechanics and I have a problem with equation (3.22). Having discussed the derivation of the classical cross section for a scattering process, Huang moves on to the quantum version of it. He states that in quantum mechanics the fundamental...

Dear all Apart from cost saving (or reduction in material)what is the technical advantage using I section instead of square section? My application is,section is going to be simply supported to the static load.myself awared that I section is good for bending loads.Instead i am using square...

Homework Statement Identify the type of conic section whose equation is given as y^2+2y=4x^2+3 Also find its vertices and foci (y-k)^2/a^2-(x-h)^2/b^2=1 Homework Equations I believe when you have x&y ^2 in an equation it can be either an ellipse or a hyperbola but if the signs are...

is there a simple way to determine the section modulus of a member made of a W and WT shape welded together, one on top of another about the x-axis. the steel manual has the properties for the individual sections; would the section modulus of each be able to be added together or will i have to...

what is the cross section area of the water?? Homework Statement Determine an expression for the cross sectional area A of the fluid in the tank as a function of D and H. Homework Equations A=pi*r2 The Attempt at a Solution i try to let the radius equal to the height but then the...

hey guys i have a question. i solved the problem but i don't understand how to do it. Two perpendicular straight wires join in the ends of a semicircular loop of radius a = 11 cm, as shown in the figure above. If the current I =6 A, what is the resultant field at the center of the circular...

Homework Statement A supernova can produce a neutron star with typical radius 10km. Assume the neutron star matter consists of iron nuclei (A=56), produced by the electron capture reaction: e^{-}+Co\rightarrowFe+\nu_{e} The matter density is \rho=10^{5} tonne mm^{-3} and the neutrino...

Hi all. This is my first time in the Physics Forums. I would like to ask for guidance in a calculation of a cross section of a process. I know the Feynman graph but I'm completely lost on how to start the calculation.. For example.. p p -> Z -> μμ Many thanks in advance..

Homework Statement When is the magnetic flux on a section of a closed surface equal to zero? A. When the magnetic field is in the direction opposite that of the section’s area vector. B. When the magnetic field is in the direction of the section’s area vector. C. When the magnetic field...

Homework Statement Which describes the magnetic flux through a section of a loop? A. It is a vector that is directed outward through the section. B. It is a vector that is directed inward through the section. C It is a vector that is tangent to the section. D. It is a scalar...

Hi all, I'm trying to understand the solution to a problem from a textbook. We're asked to find the proportionality constant for $$\frac{d\sigma_{\rm elastic}}{dq^2}\propto e^{bt},$$ where q is the momentum transfer in a scattering process, defined in elastic scattering as...

I recently saw the Evaluated Nuclear Data File provided by Brookhaven national lab., where in i saw the plot of "Neutron Energy Vs cross section (total)" for different elements. http://www.nndc.bnl.gov/sigma/index.jsp?as=1&lib=endfb7.0&nsub=10 Now what i am interested in is, can we derive or...

Is it possible to only show section numbers without chapter numbers in a LaTeX document of class "book"? For instance, Munkres' Topology text breaks things down into chapters but the sections are numbered independent of the chapter. For instance, Sections 1-11 are in Chapter 1, 12-22 in Chapter...

Hi there, I currently trying to calculate the second moment of area of an L shaped cross section. The reason for this is I have carried out a buckling experiment on a strut of this cross section and want to calculate some theoretical results to compare to my experimental results. I need the...

New here, sorry if I'm in the wrong place or unclear, etc. I've been looking at torsion on solid plates and the torsion constant. I was wondering how to handle the torsion constant on a plate of changing cross section (e.g. there are holes drilled in it, changing the area of the cross section...

Given the general equation of conic section: Ax2+Bxy+Cy2+Dx+Ey+F=0 How can we find the type of conic section from the above equation? I've used method of rotating coodinate around the origin (from Oxy to Ox'y', Ox' makes an angle θ to Ox, counterclockwise) such that the symmetry axes of the...

Here is the problem Let A be an infinite subset of \(\mathbb{R} \) that is bounded above and let \( u= \mbox{sup }A \). Show that there exists an increasing sequence \( (x_n) \)with \( x_n\in A\) for all \(n\in\mathbb{N} \) such that \(u=\lim (x_n)\). My try. Since A is infinite, it means...

here is the problem. Let \( a>0\) and \( z_1 > 0\) . define \( z_{n+1}=\sqrt{a+z_n} \) for all \( n\in \mathbb{N} \). Show that \( (z_n) \) converges and find the limit. I am supposed to use monotone convergence theorem. For that I need to prove that the sequence is bounded and monotone. I can...

Homework Statement DT fusion produces 14.1 MeV neutrons. A diagnostic for a total fusion yield is the Cu-63( n, 2n)Cu-62 reaction. A) what is the threshold for this reaction? Cu-63 also undergoes a radiative capture reaction yielding Cu-64. This reaction has a thermal cross section of 4.5b...

here is the problem from Bartle's book Let \( X=(x_n) \) be a sequence of positive real numbers such that \( \mbox{lim }(x_{n+1}/x_n) = L > 1 \). Show that \( X \) is not bounded sequence and hence is not convergent. I am using negation of the goal. So I assumed that the sequence is bounded...

Hi everyone? What is Born cross section? And what is the relation between it and observed cross section? Thank you.

Homework Statement Why don't hydrogen cross-sections exhibit resonances? Homework Equations N/A The Attempt at a Solution I was thinking it had something to do with the spin, the fact that is has only one electron, or elastic scattering, but I can't seem to wrap my brain around...

differential cross section of coulomb scattering can be expressed as a form factor times Rutherford one, we model the charge we used spherically symmetric charge density, if we replace this point charge with other distribution like Gaussian , what is the difference between these two models, is...

Hi Guys, Please see attached diagram. I have done the maths but i am not convinced. Maybe i have missed something but i have not done structural maths for a while. I am using Force = ma where m= mass and a = 9.81m/s2 I need a deflection value for a mass of 19000kg And a mass for...

Hi I have to prove that \( ^{\mathbb{R}}\mathbb{R}\;\sim\;\mathcal{P}(\mathbb{R}) \). My attempt is here. \( \mathbb{R}\;\sim\;\mathbb{R} \Rightarrow \mathbb{R}\;\precsim\;\mathbb{R}\). Since \( \{0,1\}\subseteq \mathbb{R}\Rightarrow \{0,1\}\;\precsim\;\mathbb{R}\) . I am going to make use of...

Hi I have to prove \[ ^{\mathbb{Z^+}}\mathcal{P}(\mathbb{Z^+})\;\sim\; \mathcal{P}(\mathbb{Z^+}) \] here is my attempt. I have proven that \( \mathcal{P}(\mathbb{Z^+})\;\sim\; ^{\mathbb{Z^+}}\{0,1\} \). Also I am going to use the fact that if \( A\;\sim B \) and \( C\;\sim D \) then \(...

Please help, A vehicle enters a test section of straight road at s = 0 with a speed of 50 km/h. It then undergoes an acceleration which varies with displacement as shown. Determine the velocity v of the vehicle as it passes the position s = 0.30 km. Thanks!

Homework Statement A medium carbon annealed steel rod has a rectangular cross section and must cope with a tension of 3 tonnes. The thickness of the rod is 15mm. Calculate the size of the cross section. Tension limit = 3 tonnes Thickness = 15mm Cross Section = ? Homework Equations...

Homework Statement Consider a cylindrical tank filled with water with 2.5-m depth. The water emerges from a small hole at the center of the bottom, as shown in the figure. The diameter of the hole is 1 mm. The cross-section area of the vertical water stream decreases as it falls. Find the...

Homework Statement Hi. I'm trying to calculate the cross section for this process: where \phi is a massive neutral scalar, N is a massive Majorana neutrino and \nuL is the normal SM neutrino. Homework Equations N/A The Attempt at a Solution Apparently the answer should be something like...

Homework Statement In an experiment carried out with a beam of thermal neutrons it is found that on traversing a 2mm thick foil of 197Au, some 70% of the neutrons are removed. What is the total thermal neutron cross-section for this isotope of gold? (Density of gold: 19300 kg m-3) Homework...

Homework Statement Dimensions: length - 400 mm, width - 125 mm height - 50 mm thickness - 3 mm included 6 holes for m12 bolts at the top, 4 holes for m6 bolts. will this section be able to hold a 30kg floodlight. Homework Equations The Attempt at a Solution still trying...

Homework Statement Homework Equations torque = force x distanceThe Attempt at a Solution words: hopefully this one is clearer than the last one and someone can follow what I did and figure out where I went wrong. Thanks. Answer is Ffg=5kn T, Ffh = 20 kn T (only these two members are being...

Homework Statement Hi, I'm trying to complete my laboratory write up over my christmas break, and I'm struggling to understand how to do part of it. I emailed the lab demonstrator on December 9th, and the head of labs on the 18th and I've had no reply off either, so I'd really appreciate it...

I am creating a 3D mesh for beam188 elements (L sections). Method - create keypoints, create lines between KP, define section, apply all relevant properties to the line and mesh the line. When I view the mesh (/ESHAPE,1) it appears as you would expect with an extruded L-shaped 3D...

Why is it that the differential cross section for processes like Inverse Muon Decay (IMD) are always given in the CM frame? Every paper I have seen that discusses Inverse Muon Decay gives the differential cross section in CM frame. Is it very hard to calculate the differential cross section in...

I am doing a wind tunnel experiment on aerofoil. So i need some idea to mount my aerofoil in the test section. The aerofoil is made of acrylic. So which type of stick will suitable for my aerofoil mounting. The configuration as shown in picture that attached. (Picture taken from google image).

Hi there, i have a problem trying to derive the equation for the shear centre of a thin walled slit circular section of uniform section. I have attached a photo of the question bellow. it is taken from mechanics of materials. I hope someone can help.

I do make the section of a browser, like section 3, appear automaticlly at the top of the browser when people access my website?

What is the neutron scattering Differential Cross section .. simple definition? ... Thanks

For my research purpose, I made a wind tunnel which has 0.6m rectangular section [0.2X0.2sq. meter] and 1.4m long diffuser section having porous top [top wall angle is 20deg] as follows: Wind tunnel speed is 15m/s. Even using 20deg inclination of porous top wall, there is no flow...