Cross Definition and 1000 Threads

Hey guys, I normally don't use forums for help but I've been stuck on these questions for some time now and I just want to see if there's anyone out there who can set me in the right direction. These questions are from a grade 12 Calculus and Vectors class and they relate to the cross product...

dot product and cross product. i (think dot product is like eg (1,2,4).(2,4,5) = 30 and cross product is like eg(1,2,4)x(2,4,5)=2, 8, 20) but I am not sure... and is there an order like in a.bxc do u do bxc and then.a or do u go normal left to right. but if left to right what's the rule in when...

why is the cross section of photon - proton less than the electron- photon cross section for the same photon energy??

Just a simple question, if I got two genes with 2 recessive mutants, let say the wildtype A and B with mutants a and b. And I cross truebreeding mutants (AA bb, aa BB), linkage, in this situation, doesn't matter, I'll get Aa Bb anyway, am I right ?

I know how to compute it and how to use it in equations. I do not understand what is physically happening however. When you turn a disk to the right the angular momentum is the cross product of the forces so it goes perpendicular to them and away from you. To the left would be towards you...

What is the cross product of -i x i? Is it negative 1 or is still just 0?

Would anyone know of any textbook that has explicit calculations of cross section using intermediate vector boson theory? I've looked in Perkins and Halzen+Martin but I do not see any in those texts.

Is there a difference between (1-\gamma^5) and (1-\gamma_5) ? I see the two used interchangeably when calculating cross section.

[b]1. Find axb: Given the magnitude of lal=3 and the magnitude of lbl=2. [b]2. Since I have the magnitudes, I thought maybe I could use the equation of axb=lal lbl sin theta. [b]3. I thought since I am trying to find axb that I could use 90 as the angle theta to find axb. I am...

Homework Statement 1 (H_1 - H_2) \times \hat n = J_s 2 (H_1t - H_2t) = \hat n \times J_s How does one get from the first statement to the second statement? 3 H_{1t} - H_{2t} = J_s This is causing an interesting problem when I plug in numbers, I would have just left it with statement (3) but...

I need help please on a calculus problem. I am trying to teach myself and am doing fair. I am stuck on this though. Question:find the volume using CROSS SECTIONS that are squares. base is bounded by y = x + 1 y = x squared - 1 cross sections are squares perpendicular to the x axis I...

I found this problem in the book Resnick and Halliday many years ago (1992) and I had it in my mind until 2005 or so when I was able to get some advance. "If you want to walk through a distance L in a rainy day, in order to get wet the little as possible what would you do, run as fast as...

Force F = (9.0 N) i hat + (-4.0 N) k hat acts on a pebble with position vector r = (3.00 m) j hat + (-1.0 m) k hat, relative to the origin.(a) What is the resulting torque acting on the pebble about the origin? ( N·m) i hat + ( N·m) j hat + ( N·m) k hat (b) What is the resulting torque...

Hi. I have an integral of a cross product: \int a\times b(t)dt a does not depend on t. How can I move it outside? Is this legal: a\times\int b(t)dt ?

If vectors V_1 and V_2 are perpendicular, lV_1 x V_2l =? I know that if they are parallel for vector cross product, they equal 0.

Homework Statement B = grad(A) Find A If one is given B z-hat Homework Equations The Attempt at a Solution What mathematical operation would I apply to solve this?

Homework Statement Find the area of a triangle `PQR`, where `P=(0,4,4)`, `Q=(2,-6,-5)`, and `R=(-3,-5,6)` The Attempt at a Solution The vector PQ = (2, -10, -9) The vector PR = (-3, -9, 2) Using matrixes I set up something that looks like this... I J K 2 -10 -9 -3 -9...

Cross section means the effective size of a nucleus for capturing a neutron, am I right? But what makes the cross sections for different nucleus different? I am a bit puzzled, why the cross section for Boron(for example) is so high?

I need to use this libraries with confidence. Any articles that involves benchmarking of these cross sections?

Hi all, I'm trying to teach myself high energy physics and was wondering if anyone knew a good reference site on calculating cross sections. I'm specifically trying to calculate the cross section for \nu _{\mu} + e^- \rightarrow \mu ^- + \nu_e using the 4-fermi interaction. Are there any good...

Hello all, it might be funny! but i am stuck to it! what is the vector cross product formula in spherical and cylindrical coordinates?! I know for Cartesian coordinate we have that nice looking determinant. but what about the other coordinates. I had looks to all the math books (like...

[SOLVED] Trihybrid Cross Problem Hi, I need help trying to figure out how to solve this question: Assume that in rabbits there are three different independently assorting autosomal loci that affect coat color. A colorless-pigment precursor V is converted to a colorless precursor W by action...

the question is: u = 9i-6j and v = 5i+bj for what value of b would u-v point in the same direction as w = 7i-3j? can anyone help me get started on this problem, I am not looking for answers just a little bit of help because I'm confused.. thanks

geometric algebra cross product -------------------------------------------------------------------------------- Homework Statement [/b] my text (Geometric Algebra for Physicists, by Doran and Lasenby), p. 69, deals with rotating frame {fsubk} (I assume in 3D) d/dt (fsubk) = omega X...

Homework Statement [/b] my text (Geometric Algebra for Physicists, by Doran and Lasenby), p. 69, deals with rotating frame {fsubk} (I assume in 3D) d/dt (fsubk) = omega X fsubk omega being angular velocity then omega X fsubk = (-I omega) dot fsubk = fsubk dot (I omega), where...

Problem Determine the differential and total cross sections for scattering from a "hard sphere" of radius R ("hard" means impenetrable). Relevant Formulae \sigma (\Omega) d \Omega = \frac{number \ of \ particles \ scattered \ into \ solid \ angle \ per \ unit \ time}{incident \ intensity}...

[SOLVED] Vector, cross product, and integral Homework Statement Evaluate: {\int \textbf{F} \times \texttt{d}\textbf{v}}. \textbf{F} and \textbf{v} are both vector fields in \mathbb{R}^3 Homework Equations \texttt{d}\textbf{v} = (\nabla \otimes \textbf{v} ) \texttt{d}\textbf{r} The Attempt...

Im currently studying different kinds of processes in QFT. Does somebody know where to find all the calculus done step by step on the web. It will be very helpfull. thanks in advance, Marco.

If a, b, and c are vectors, and a=b x c, and a and c are known, how do I solve for b? b=a/c ? I don't think we've covered diving vectors, and since the cross-product is a special case of multiplying vectors (as opposed to dot product), I'm not sure this is allowed anyway. I'm trying to...

Homework Statement If d1 = 4i - 10j + 2k and d2 = 9i - 10j + 6k, then what is (d1 + d2) · (d1 × 4d2)? Homework Equations Know how to do the cross product and dot product The Attempt at a Solution For the answer i got 9.6i + 56j -127.68k. How do i express that as a scalar for an...

Homework Statement If you have two functions dependent on t, A(t) and B(t). Prove their derivatives are as follows: d(A (dot) B) / dt = [A (dot) (dB)/(d(t)] + [d(A)/d(t) (dot) B] {Where "(dot)" acts as the dot product} d(A x B) / dt = [A x (dB)/(d(t)] + [d(A)/d(t) x B]...

What does it mean when they say s wave cross section, p wave cross section .. ?

[SOLVED] derivative of a cross product Homework Statement In some lecture notes I'm reading they jump straight from \frac{d}{d\mathbf{r}}( \frac{m}{2} |\mathbf{\omega}\times\mathbf{r}|^2) to \mathbf{r}\omega^2-\mathbf{\omega}(\mathbf{\omega}.\mathbf{r}) Homework Equations The...

[SOLVED] normalizing a cross product Homework Statement How does normalizing (T(t) x T'(t)) equal ||T'(t)||? Homework Equations r'(t) x r''(t) = ||r'(t)||^2·(T(t) x T'(t)) ||r'(t) x r''(t)|| = ||r'(t)||^2·||T'(t)|| The Attempt at a Solution This doesn't bode well with me...

Homework Statement We know that T(t) = r'(t)/||r'(t)||, or equivalently, r'(t) = ||r'(t)||·T(t). Differentiate this equation to find r''(t), then show that r'(t) x r''(t) = ||r'(t)||^2 · (T(t) x T'(t)). Homework Equations r''(t) = ||r'(t)||'·T(t) + T'(t)·||r'(t)|| The Attempt at...

Homework Statement I've been asked to find the cross section of a hydrogen atom in thermal equalibrum at 6000K for a photon which induces a transition from the ground state to the first excited state. The density of states for n=2 is 4x the density of states for n=1 i.e. g(E2) = 4*g(E1)...

Dear Users, I would like to ask you how can I plot d_sigma/d_Pt graph for proton proton collisions using pythia event generator. I am also using root macro which plot d_N/d_Pt graph for pion and I have also attached this for you. I would be garetful if you could tell me how can I convert this...

Is there such a thing as a cross product for R4 vectors? Can you use the permutation symbol to express it in the same way that it can be expressed in R3? Would the correct way to write it be: e _{i,j,k,l} u _{j} v _{k}?

Homework Statement A force F = (5 i - 1 j) N acts on a particle that undergoes a displacement r = (2 i + j) m. (a) Find the work done by the force on the particle. (Calculate all numerical answers to three significant figures.) (b) What is the angle between F and r? * the problem required us...

Homework Statement A, B, C and D are sets if A x B is a subset of C x D then A is a subset of C and B is a subset of D. The Attempt at a Solution My attempt by contraposition. Assume A is not a subset of C or B is not a subset of D. There exists an 'a' which is an element of A...

Q:Given non-zero vectors u and v, find a vector x such that both equalitites x dot u=|u|, and x cross u = v hold. What should be the mutual position of the given vectors u and v in space, so that the problem has a solution? What I've got so far: Setting x = au + b(u cross v) I have that...

I'm extracting data from a Monte Carlo sim. and i need to extract the differential cross-sections of the resultant protons and neutrons in momentum and rapidity space. ie \frac{d\sigma}{dy} ; \frac{d\sigma}{dp} and \frac{d^2\sigma}{dydp} where I know the values of y and p...

I'm writing a paper on Thorium utilization in nuclear reactors. In this connection I'm looking for figures which describe the neutron capture and neutron fission cross sections over a wide energy range (not only thermal). There are probably some online resources unbeknown to me, any hints?

Homework Statement A beam of \alpha-particles, of kinetic energy 5.3 MeV and intensity 10^{4} particle/sec, is incident normally on gold foil with thinckness 1 x 10^{-5} cm. (The density, atomic weight and atomic number of gold are 19.3 g/cm, 197 and 79 respectively.) A particle counter of...

Homework Statement Sketch a 3-dimensional picture showing the horizontal plane, a point P on the plane, a vertical line through P, and three vectors at P: vector A points vertically upward; vector B points toward the east; vector C points toward the south. Now determine the cross...

Homework Statement find B from F=q(v X B), where F is magnetic force, q = charge, v = velocity, B = magnetic field. Carrying out 3 experiments, we find that if v_1 = i, (F/q)_1 = 2k - 4j v_2 = j, (F/q)_2 = 4i - k v_3 = k, (F/q)_3 = j - 2i where i,j,k are the unit cartesian vectors This...

I'm calculating an ionization cross section in partially ionized plasma, with taking into account of correlation effects. I'm trying to do it with help of variation phase method. Please, help me to find some link to useful articles.

Suppose that a particle's position is given by the expression in the attachment Explain: 1. When does the particle first cross the negative x axis? 2. Find the particle's velocity as a function of time. Express your answer using unit vectors.(e.g., A i_unit+ B j_unit, where A and B...

Homework Statement Given that A = 2i + 4j, evaluate each of the following. (Hint: This question can be answered without computation.) (a) What is AxB when B = 8i + 16j? (b) What is AxB when B = -8i - 16j? Homework Equations AxB=(Axi + Ayj) x (Bxi +Byj) =(AxBx)(i x i)...

I'm having trouble relating the cross product form |a||b|sin(theta) to its component form (a1b2 - a2b1) ... and so on... I know how to do this mathematically so please don't just suggest some proof that I can find in every textbook... The component form involves the solutions to equations...