Vector Definition and 1000 Threads

f(\vec{x}+\epsilon \vec{y})-f(\vec{x})=\epsilon \mbox{d}f_{\vec{x}}(\vec{y})+O(\epsilon^2). Is ##\mbox{d}f_{\vec{x}}(\vec{y})## dual vector and why? Is it because ##\mbox{d}## is linear transformation? Also why equality f(\vec{x}+\epsilon \vec{y})-f(\vec{x})=\epsilon...

Hi there I'm having a hard time trying to understand how come ∂r^/∂Φ = Φ^ ,∂Φ/∂Φ = -r^ -> these 2 are properties that lead to general formula. I've been thinking about it and I couldn't explain it. I understand every step of "how to get Divergence of a vector function in Cylindrical...

Suppose I have a vector space V and a matrix M such that multiplying every vector in V by M creates another vector space W. Now suppose I have another matrix A that I can also use to change vectors in V into other vectors. Does there exist a third matrix B such that - for any vector v1 in V -...

Homework Statement Two points in a plane have polar coordinates P1(2.500m, pie/6) and P2(3.800m, 2pie/3) . Determine their Cartesian coordinates and the distance between them in the Cartesian coordinate system. Round the distance to a nearest centimeter.Homework Equations Ax=Acosθ Ay=Asinθ...

I am trying to improve my understanding of Lie groups and the operations of left multiplication and pushforward. I have been looking at these notes: https://math.stackexchange.com/questions/2527648/left-invariant-vector-fields-example...

I know that a vector is a tool to help with quantities that have both a magnitude a direction. At a given point in space, a vector has a particular magnitude and direction and if we take any other direction at the same point we can get a projection of this vector in that direction. Tensor is a...

I know that n-body problem can be complicated, but that's for the dynamics. What about a static case: e.g. if I have the distances of several bodies A, B and C etc. and their distance to a reference mass m, can I just use the vector addition of the Newton's gravitational force to add up all of...

Homework Statement Let a charge oscillate on a straight line between -a to +a with a frequency ω and according to the law: κ (x.t) = κ° sin(πx/a) e^(-iωt) I have to find the following: 1. Vector potential in the dipole approximation 2. Integral of the intensity of radiation Homework...

In Special Relativity, we have the four vector, (E/c, px, py, pz). However, isn't the first term just `p` given that `E=pc` for a photon? Why is it an energy-momentum four vector when the first term isn't really energy but momentum?

I just ran into a Scientific American article (link below) based on a recently updated paper (2nd link). https://www.scientificamerican.com/article/quantum-physics-may-be-even-spookier-than-you-think/ https://arxiv.org/abs/1707.09483 It was the first time I had run into the term "Two-State...

ei=i+j+2vk , how to find the dual basis vector if the above is a natural base?

Homework Statement >There are three vector $$ \vec a ,\vec b, \vec c$$ in three-dimensional real vector space, and the inner product between them $$\vec a . \vec a=\vec b.\vec b=\vec a.\vec c=1, \vec a.\vec b=0, \vec c.\vec c=4 $$ When setting $$x = \vec b.\vec c$$ , (dot here means dot...

|r|2=r.r=uiei.ujej Why are i and j different because we are dotting the same vector?

Homework Statement Let V = RR be the vector space of the pointwise functions from R to R. Determine whether or not the following subsets W contained in V are subspaces of V. Homework Equations W = {f ∈ V : f(1) = 1} W = {f ∈ V: f(1) = 0} W = {f ∈ V : ∃f ''(0)} W = {f ∈ V: ∃f ''(x) ∀x ∈ R} The...

Griffith's writes in chapter 7 electrodynamics that D1.a - D2.a = sigma. a. But minus sine comes when we evaluate the dot product first. How does the minus sign occur without evaluating the dot product?

If we have a some wire (length L) with a PD of V from one end to the next and a current I moving along it we can work out the Poynting vector. It's pointing radially inwards and so tells you the energy per unit time per unit area flowing into the the surface of the wire. What I don't understand...

I have seen the other threads on an infinitely long wires vector potential.Its obvious that really small wires are just infinitely long cylinders: ∇xA=B ∫∇xA.da=∫B.da ∫A.dl = ∫B.da = φ(flux) For an infinite cylinder A.2πri=B.2πrih A=Bh A=μ0*I*h/(2π*r) Now for a cylinder of radius limr->0 =>...

Hi guys, I have encountered a problem in fluid mechanics that gives a three-dimensional vector differential equation \begin{equation} a \vec{f} + \nabla{a} + b \nabla{c} = \vec{0} \end{equation} where a, b, and c are unknown scalar functions of three-dimensional space and f is a known vector...

Homework Statement I don't understand how to form an equation using the knowledge that, 'When ##t=4##, ##P## is moving parallel to the vector ##\mathbf {j}##'. I've seen the solution, and not a single part of it makes sense. I haven't attempted any question like this before, so I have no idea...

Hi I wish to use Python to create art which can be exported as dxf files for use with laser cutters.While Processing is available for Python, it only creates raster images. What are my options if I want to create vector images? This may be the wrong forum for this question... If it is, where...

Homework Statement Given $$\phi = x^{2} +y^{2}-z^{2}-1 $$ Calculate the unit normal to level surface φ = 0 at the point r = (0,1,0) Homework Equations $$ \hat{\mathbf n} = \frac{∇\phi}{|\phi|}$$ $$ z = \sqrt{x^{2}+y^{2} -1} $$ $$ \mathbf n = (1,0,(\frac{\partial z}{\partial x})_{P})...

in this problem i can solve v = ω x r = <0, -ωrsinψ, 0> in cartesian coordinates but i don't understand A in sphericle coordinates why? (inside) A = ⅓μ0Rσ(ω x r) = ⅓μ0Rσωrsin(θ) θ^ how to convert coordinate ?

Homework Statement Hello, I am currently studying mathematics and physics on my own, and I ran into a type of problem in physics that is a bit unclear to me. Say we have pulley at the top of an inclined plane with a base angle of alpha and the top angle is alpha. Homework Equations I assume...

Hello! I just started reading about ##Z_2## graded vector spaces (and graded vector spaces in general) and I want to make sure I understand from the beginning. So the definition, as I understand it, is that a graded vector space can be decomposed into subspaces of degree 0 and 1. So ##V=V_1...

Homework Statement I reference problem 9.10 Purcell's Electricity and Magnetism (3rd ed). A very thin straight wire carries current ##I## from infinity radially inward onto a conducting shell with radius R. Show that the total flux of the Poynting vector away from an imaginary tube of radius...

Hi. If I have a vector v , say for velocity for example then v.v = v2 and I differentiate wrt t v.v I get 2v.dv/dt but if I differentiate v2 I get 2v dv/dt but v.dv.dt is not the same as v dv/dt so what am I doing wrong ? Thanks

Reading Chandrasekhar's The mathematical theory of black holes, I reached the point in which the Newman-Penrose GR formalism is explained. Actually I'm able to grasp and understand the usage of null tetrads in GR, but The null tetrads used in this formalism, are very special, since are made by...

Information Given: In the figure, a square of edge length 17.0 cm is formed by four spheres of masses m1 = 4.70 g, m2 = 2.90 g, m3 = 0.800 g, and m4 = 4.70 g. Question: In unit-vector notation, what is the net gravitational force from them on a central sphere with mass m5 = 2.90 g? Attempted...

Homework Statement Homework EquationsThe Attempt at a Solution My answer is d = |(a-b)x(p-b)|/|(b-a|). I first find out the area of the parallelogram produced by BA and BP and divide the area by length AB to get the height. Why am I wrong?

Homework Statement Is the following conclusion correct? Assume there's an equation with vectors on both sides. Taking the dot product of this equation with vectors on both sides loses information, but information will not lose when taking dot products with higher rank tensors on both sides...

I am sure that the vector potential of a toroid isn't 0 even though its magnetic field is , does anyone have a derivation for the its the vector potential at a point P(x,y,z) outside the toroid ? i expect that since its curl is 0 we have a general form of : A = f(!x)ex + g(!y)ey+m(!z)ez Such...

Hi, I've got this problem I'm trying to work out. The problem seems simple, but I don't think I have a good way to construct a way to solve it. This is the problem. Let P and Q be two points with position vectors p and q and let R be a point midway between these two. Find an expression for the...

I studied the vector analysis in Arfken and Weber's textbook : Mathematical Methods for Physicists 5th edition. In this book they give the definition of vectors in N dimensions as the following: The set of ##N## quantities ##V_{j}## is said to be the components of an N-dimensional vector ##V##...

How do we express the locality of a vector space in general relativity? I mean, it's not clear what the boundaries of a given vector space are. To put in another way, we could, in principle, blindly consider that we have the entire of ##\mathbb{R}^4## at our disposal to describe, say, the...

I was going through vector and scalar quantities (the way they are taught in high school), and this is how I think students are supposed to understand it: Scalar quantities are quantities that add like numbers. For e.g. Mass. If I add 100 g of water to a bucket and then add a further 100 g, I...

According to my understanding, option D is the only possible value of R. I don't understand how options A, B and C are included. Please explain this question. Thanks. (regards)

Hi all, i tried to do this question but got stuck on the last point . Can anyone help me please? The general form of vector potential: I got the answer for A1 vector potential but don't know what assumptions i need to get the expression for the A2. Does anyone know how one can derive it...

Homework Statement Problem- Determine if the set of all function y(t) which have period 2pi forms a vector space under operations of function addition and multiplication of a function by a constant. What I know- So I know this involves sin, cos, sec, and csc. Also I know that a vector space...

I feel like the vector space ##\mathbb{R}^n## differs from other vector spaces, like ##\mathbb{P}##. For example, if we wrote down an element of ##\mathbb{P}##, like ##1+2t^2##, this is an object in its own right, with no reference to any coordinate system or basis. However, when I write down an...

I learned that the Poynting vector was the electromagnetic density of momentum but recently, while reading the Electromagnetic_stress–energy_tensor article at Wikipedia, I thought about the implications of the momentum conservation equation and arrived to an inconsistency, this equation is...

Homework Statement Two parallel very long threads are uniformly charged with linear charge density of 10-8 C/cm . Distance between them is 15 cm. Find electric field vector at a distance of 15 cm from both threads. Homework Equations E*dA=Qenclosed/permittivity of free space The Attempt at a...

Homework Statement What's the vector equation for a plane which contains the point ##(-2,2,1)## and whose vectors ##(1,1,2)## and ##(2,1,-1)## are parallel to it? Homework Equations I think the relevant here is - The plane equation. The Attempt at a Solution [/B] We can go through...

AIUI, every normal matrix has a full eigenvector solution, and there is only 1 *normalized* modal matrix as the solution (let's presume unique eigenvalues so as to avoid the degenerate case of shared eigenvalues), and the columns of the modal matrix, which are the (normalized) eigenvectors, are...

Given an ##N## dimensional binary vector ##\mathbf{v}## whose conversion to decimal is equal to ##j##, is there a way to linearly map the vector ##\mathbf{v}## to an ##{2^N}## dimensional binary vector ##\mathbf{e}## whose ##(j+1)##-th element is equal to ##1## (assuming the index starts...

Homework Statement Take as input from the user an integer N. We don't want the user to enter very large integers, so exit with an error message if N>20. You may assume that N is an integer (and not a real number) and also that it is positive. Make two vectors v1 and v2 using v1.append() and...

Homework Statement Write an alternate vector equation for the following line. Change both the point and the direction vector: w⃗ =(4,−1,3)+t(−2,1,7) Homework EquationsThe Attempt at a Solution Did I write a proper alternate vector equation here? I'm still new to vectors in 3-space any tips or...

Homework Statement The velocity of a plane is 625 km/h northwest. a) Draw a diagram of this vector, including the magnitude and direction. b) Determine the horizontal and vertical components of this vector. Round your answers to the nearest whole number. c) Give the coordinates of the vector...

Homework Statement Given the following diagram, use vector addition to sketch the resultants: a) u→−2v→ b) 3v→−u→ Homework EquationsThe Attempt at a Solution For this question I am fairly certain that it is correct but for some reason I'm doubting myself. I was wondering if I could get some...

Homework Statement Find u→ in Cartesian form if u→ is a vector in the first quadrant, ∣u→∣=8 and the direction of u→ is 75° in standard position. Round each of the coordinates to one decimal place. Homework Equations none The Attempt at a Solution I'm certain this is correct, but some guy at...

Homework Statement Hi, I'm having some doubts about the gradient. In my lecture notes the gradient of a scalar field at a point is defined to point in the direction of maximum rate of change and have a magnitude corresponding to the magnitude of that maximum rate of change of the scalar field...