Cross Definition and 1000 Threads

The cross product between two vectors \vec{A}x\vec{B} and \vec{C} is given by the following equation: (\vec{A}x\vec{B})x\vec{C}=(\vec{A}.\vec{C})\vec{B}-(\vec{B}.\vec{C})\vec{A} Well, as I'm sure you know, proving something is true is different than proving how something is true. In this proof...

Homework Statement http://www.scribd.com/doc/82645310 In Figure 3-31, the lines AB and CD are the center lines of two conduits 1 ft. and 2 ft. in diameter respectively. Determine the maximum value of z so that the two may pass without interference. Conduit CD must pass under AB...

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...

Is it possible to nontrivially represent the cross product of a vector field \vec{f}(x,y,z) with its conjugate as the gradient of some scalar field \phi(x,y,z)? In other words, can the PDE \vec{\nabla}\phi(x,y,z) = \vec{f}(x,y,z)\times\vec{f}^\ast(x,y,z) be nontrivially (no constant...

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 what I have [SIZE="3"] A=xro+yr1 B=yro+xr1 I need to find A x B I am confused about do it because The components of A and B are in terms of vectors If A = 3i + 4j + 7k and B = 2i + 2j + 1k I would have no problem (these numbers are meaningless just giving an example)...

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

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...

Explain, for example, why you can cross three vectors (two at a time, following the usual rules), but not dot three vectors. Do you see the dot product "in action" in matrix multiplication? What sort of insights can the dot product give when trying to comprehend matrix multiplication?

Homework Statement A defining property of a vector is that its components must transform in a particular fashio under a rotation. for a counterclockwise rotation around the z-axis, by and angle ∅ the components Ax, Ay, and Az of a vector A transform in the following fashion: Ax --> Ax' =...

Homework Statement u (dot) [ u x v] Homework Equations The Attempt at a Solution The answer is 0, but I'm not sure why. Do you simplify [u x v], then use that vector to dot it with u? Or can you distribute the u to both u and v?

The mean free path is usually determined via the scattering cross section σ; one starts with a differential equation for the intensity dI(x)= -n\,\sigma\,I(x)\,dx Are there generalizations for this derivation for energy-dependent cross sections σ(E)?

hi guys, m a lil stuck here what voltage would be rquired to heat a 7cm long copper wire of .75mm diameter in about 2-3 seconds.the target temp is 400-450c. dr ankit

Homework Statement see attachment Homework Equations The Attempt at a Solution i found AB got <4,2,3> i found AD got <1,-1,1> i found |ABxAD| got square root of 62 not exactly sure what i am doing wrong thanks for any help

Homework Statement Let x(t) be a transmitted radar pulse. The received radar pulse is y(t). y(t)=ax(t-t_{d})+v(t) Where v(t) is the additive noise and td is the time delay. The signals x(t) and y(t) are sampled and processed digitally to determine the delay The discrete time signals...

I am trying to get an intuition behind the cross product but i seem to get stuck with understanding why we make the vector perpendicular to the other two? I understand the need to define an orientation for physical systems like torque (ccw or cw) but then why make it a vector and why choose...

Homework Statement Find the magnitude of the vector product w ⃗x u, where w=<1,0,1> and u=<1,1,0>. Homework Equations ||w x u|| = ||w|| ||u|| sin θ cos θ = \frac{w.u}{||w|| ||u||} The Attempt at a Solution w ⃗x u ⃗= -i ̂+j ̂+k ̂ ‖||w ⃗x u|| ⃗ ‖= √3 but...

Just learning about vectors in 3 dimensions. Would it be correct to think of the cross product vector like a resultant vector? Is it similar to the displacement? If so, why is it always 90 degrees from both original vectors? If anyone has some deeper insight into any of these vector topics...

cross products= vector(a)*vector(b)=Magnitude(a)*magnitude(b)*cos(theta) I'm having trouble on how to get started...

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 For arbitrary vector fields A and B show that; ∇ ^ (A^B) = (∇ . B)A - (∇.A)B + (B.∇)A - (A.∇)B Homework Equations where (A.∇)B = ((A.∇)Bx, (A.∇)By, (A.∇)Bz) and (A.∇)f = Ax δf/δx + Ay δf/δy + Az δf/δz = (Ax, Ay, Az)( δf/δx, δf/δy, δf/δz)f The Attempt at a...

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...

I'm new to the field of signal processing and currently reading a paper which it uses cross-correlation of two signals for detecting some machine failures. But I'm confused with the complex conjugate in the equations. Take equation from wikipedia as example: (f\star g)(t)\equiv \int_{-\infty...

This may be more of a MATLAB question, and if so, I do apologize for posting this in the wrong place. I am doing a project on the Buttke scheme, which is a numerical approximation to the Biot-Savart Law. I am almost finished, but I am having trouble writing the code. The scheme is...

Homework Statement http://i.imgur.com/a36Mj.png Homework Equations The Attempt at a Solution Slow cross fast gives me positive z direction...

I am trying to figure out the following If R2 = 1.043j -1.143k Then how can R2 = 1.547

Homework Statement find the volume of the solid whose base is the region bounded by y^2=9x and x=1 in the xy-plane. each cross section perpendicular to the x-axis is an isosceles right triangle with its hypotenuse in the xy-plane. Homework Equations V=\int_{a}^{b}A(x)dx The Attempt...

Problem: Prove A x (B + C) = A x C + A x B Related equations: Cross product Attempts: Not even remotely sure where to start with this, other than I need to use the cross product rule.

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...

Homework Statement (Z, Q) and (W, S) are two partially ordered sets. There is a relation I on Z x W (Z cross W) that is defined... for all (a, b), (c, d) in Z x W, set (a, b) I (c, d) if and only if aQc and bSd. How does one prove that (Z x W, I) is a partially ordered set? Homework...

I was wondering, is the definition of the cross product the same for complex vectors? And if it is, then how is its geometric interpretation, that is ||\mathbf{a}\times\mathbf{b}||=||\mathbf{a}|| \; ||\mathbf{b}|| \sin\theta Thanks.

Spatial Cross Correlation help urgently needed! I am working on Cross Correlation at the moment with varying degrees of success. I have figured out how to do Cross and Auto Correlation but am lost tryng to understand spatial CC. I can't seem to find any helpful resources for what I am working...

I want to know how one might calculate the cross correlation of two signals by hand. I know that there are a myriad of software applications that will do this for me but I want to understand how it is done by hand. I'm using the expression: ccxy[k] = ∑ x[n]. y[n+k] I'm just not too sure what the...

Homework Statement Assuming that ∅ is a differentiable scalar valued function and F a differentiable vector field, derive the following identities. a)∇(dotted with)(∅F) = ∇∅(dotted with)F + ∅∇(dotted with)F b)∇(crossed with)(∅F) = ∇∅(crossed with)F + ∅∇(crossed with)F Homework Equations The...

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

Hi all, Just having some trouble understanding a certain example of cross product. It's actually for physics, but figured it belongs in this forum. In the question I am supposed to cross (dl)y hat with (x1)x hat. So I go (0 dl 0) x (x1 0 0) = (-x1dl)z hat. But turns out the answer the...

I know the cross product and dot product of euclidean space R^3. But I wanted to know if there is a way of thinking the cross product "in terms of" the dot product. That is because the dot product can be generalized to an inner product, and from R^3 to an arbitrary inner vector space (and...

Homework Statement For the general case. I need help finding the cross product for the angular momentum. Say you have a particle at a position r= xi+yj+zk with a velocity of xi+yj+zk and a known mass. How do you find the angular momentum? Homework Equations L=mvr The Attempt at a...

I do not understand the interpretation of the http://hyperphysics.phy-astr.gsu.edu/hbase/rutsca.html" . To me, that equation says: (1) for a given θ, the proportion of particles exiting at θ does NOT depend on mass or charge; (2) if you integrated over all possible scattering angles, you...

Given the following cross product equation: \vec{A}\times\vec{B}=\vec{C} How to express \vec{A} in term of \vec{B} and \vec{C} (or \vec{B} in term of \vec{A} and \vec{C} ). I think the question I want to ask can also be rephrased as if one was told that a known vector when cross product with...

My question is simple: I understand that if u x v = 0 , then u and v are parallel, but what does that 0 mean? You can't obtain 0 by crossing two vectors. By 0, does it mean (0,0,0)?

I have a question regarding cross products and dot products. What is the difference, and are there any similarities? What ARE cross products and what are their functions? What ARE dot products and what are their functions? What do we use them for? Thank you, Joyci116

F = 5i + 3j Newtons acts 3 m to the right of the origin (x is horizontal and y is vertical). What moment does this force produce about the origin? Use the vector cross product. "Great works are performed

Rhodium has been measured and the following values have been obtained for the resonance parameters of a well-isolated resonance Eo=1.26 ev , σo=5000 b , Γ = 0.156 ev , σs=5.5 b , Is there anyone can help me HOW to calculate the thermal absorption cross section ? I'm disparate I don't know how to...

For tangent plane equation z-z0 = f{x}(x0,y0)(x-x0) + f{y}(x0,y0)(y-y0) how come there is no cross product of the partial derivatives f{x} X f{y} to give the normal vector for the plane?

Homework Statement The base region of a solid is bounded by y=x, y=(x-1)^2, and x = 1. The cross sections are semicircles perpendicular to the x-axis. Write a riemann sum and definite integral. Homework Equations The Attempt at a Solution First, I wrote down the formula...

Homework Statement A cross-section of a cylindrical high voltage terminal (inner cylinder) of a van de Graaff generator, surrounded by an 'intershield' (middle cylinder) and a pressure vessel (outer cylinder). The gas in the pressure vessel breaks down in electric fields greater than...

Not sure if this is the correct section. I apologize if it's not. Homework Statement For any vectors \vec{a}, \vec{b}, \vec{c} show that: (\vec{a} \times \vec{b} ) \times \vec{c} lies in the plane of \vec{a} and \vec{b} Homework Equations The Attempt at a Solution I assigned \vec{a} =...

I'm currently starting a large comp-astro project, and trying to understand a bit of the background about heading of Hydrogen and Helium IGM clouds I am a bit confused about the the actual heating process. From the standard photoelectric effect, frequency has to pass a certain frequency (or...