Dimensions Definition and 1000 Threads

I am trying to teach myself AS maths. This is from Introducing mechanics a txt book by Jefferson and Beadsworth. exercise 2C question 1 part vi) Question given vector b=6i-3j-2k; |b| is established as = 7 by calculation Question Calculate the angles between b and positive x-, y- and z-...

Homework Statement tp=√(Gh/c^5) This quantity, tp, is called the Planck time and is thought to be the earliest time, after the creation of the Universe, at which the currently known laws of physics can be applied. Extra info(I don't know is it going to be helpful for solving this...

What are the "Extra Dimensions" in the LHC experiment? First of all, I'd like you people to know that I'm a 10th grader. So yes, silly questions may follow. As the topic says, I want to have an idea of what the 'extra dimensions', that might possibly be discovered in the LHC experiment...

what are the dimensions of angles?

Homework Statement A particle leaves the origin with an initial velocity v = 3.92i , in m/s. It experiences a constant acceleration a = -1.00i -0.80j , in m/s2. What is the velocity of the particle when it reaches its maximum x coordinate? i-component of velocity? j-component of the...

Problem in equations of kinematics in two dimensions..please help Hi, I'm a first year physics student and am studying equations of kinematics in two dimensions and projectile motion. I was given the following question as homework to prep for my first exam this Wednesday. I'm pretty solid on...

Homework Statement Let A = (a_1, . . . , a_{2008}) \in \Re^{2008}, where a_i = \frac{1}{2^{i}} for each i = 1, . . . , 2008. Find the distance from the point A to the origin. Please express your answer in the form \sqrt{\frac{a}{b}} where a, b are integers. Homework Equations Extended...

Given F = (-20i + 50j = 10k) 1. The component of the foce projected along the pole AO. 2. The magnitude of the projected component of the F along the pole AO. I have no idea where to begin, I think I need to find the angles but I'm not sure how in three dimensions. (please excuse...

Well i do understand about the 8 fundamental dimensions in physics, but i cannot understand what makes only the length, mass and time to commute with one another to produce derived units like force or acceleration. Why cannot we have a unit something like K^2 or sqrt(candella)?

Just wondering. All this stuff of the brane world, where spacetime is a 3-brane inside a 10 dim world... is not the same than telling that we want to use non compact extra dimensions?

Homework Statement Find the dimensions of a rectangular box with the largest volume with surface area 64cm^2. Homework Equations area of a rectangular prism 2xy+2yz+2xz The Attempt at a Solution took 2xy+2yz+2xz=64 rearranging for z: z=(xy-32)/(y+x) partial derivative of z...

1) Which of the equations below is dimension- ally correct? a. y = (2 m) cos(k x), k = 2 m-1 b. v = v0 + a x my work for: a) cos(kx) = 2ym-1 So this would lead to k = (1/x)cos-1(2ym-1) But i don't know whether the COSINE operation on RHS changes m-1 to any other unit or not. So...

Hello folks, this is going to be a bit longish, but please bear with me, I'm going nuts over this. For a term paper I am working through a paper on higher dimensional spacetimes by Andrew, Bolen and Middleton. You can http://arxiv.org/abs/0708.0373" . My problem/confusion is in...

hi, as the topic title suggests, is that possible? i was reading an article on string theory and i vaguely recall that humans live in a 3d world with an additional dimension of time. if we can live in such a space time dimension, would it be possible that there are organisms/beings living...

Hello there, I'm currently trying to get my head around General Relativity for a term paper; the twist is that I'm dealing with an arbitrary amount of dimensions, that is 4+d, where d is unspecified. Now the maple tensor package does calculation with some fixed amount of dimensions just...

Hi people, I just need to verify that I understand this correctly. For some four dimensional manifold and group of isometries: the dimension of the isometry group is given by the number of Killing vectors, while the dimension of the orbit group is given by the number of linearly...

This may be a stupid question, but I have been curious about it for awhile. Before string theory, extra dimensions seem not to be taken seriously. But if gravity warps space doesn't it need another dimension to warp into? I saw Brian Green on TV and I thought he suggested that you don't, but he...

This is a question in my textbook: "The hyperplanes H1 and H2 have dimensions p and q, respectively. What is the smallest dimension which the hyperplane H3 must have in order to be sure to contain both H1 and H2?" I reasoned it out like this. A basis for H1 would be x1 + x2 +...+ xp...

I bought a book on susy and there is a chapter on spinors in d-dimensions. Now, maybe I am extremely dumb but I just can't understand the first few lines! EDIT: I was being very dumb except that I think there is a typo...See below... BEGINNING OF QUOTE Consider a d-dimensional...

As far as I remember, I heard from someone that the matrix \gamma^5=i\gamma^0\gamma^1\gamma^2\gamma^3 also known as the chirality operator in 3+1 dimension is not defined in odd dimensions. I do not understand why that should be the case. Suppose I am in the 4+1 dimension and I choose one...

Is there any fundamental difference between the 3 dimensions of space that we experience. Such as the difference that we intuitively feel between the time and space dimensions

Homework Statement If A is a 6x6 matrix with characteristic polynomial: x^2(x-1)(x-2)^3 what are the possible dimensions of the eigenspaces? The Attempt at a Solution The solution given is that, for each each eigenspace, the smallest possible dimension is 1 and the largest is the...

How does one calculate the number of components a Dirac spinor in arbitrary dimensions? As far as I understand, the textbooks treat the four spacetime dimensions and here the spinor has four components because the gamma matrices must be 4x4 in nature to satisfy the required algebra. Now suppose...

I read somewhere that string theory could be disproved if it is found out that the universe expanded at a certain speed as this would cause the extra dimensions to unravel and therefore mean that string theory could not describe our universe. I do not understand why the extra dimensions would...

I don't know anything about GTR, nor do I know anything about differential geometry. But I have one maybe stupid question: As far as I know space-time in general relativity is represented by a pseudo-riemannian manifold. And according to Whitney's (or Nash's? - don't know who is in charge here)...

Homework Statement Does the wave function have a dimension? If it does, what are the dimensions for 1D and 2D box problems?Can you generalise this to n dimensions? Homework Equations The Attempt at a Solution Yes, it does have dimensions. For 1D box it's [tex] m^{-2} [tex]...

My main question is if the Maxwell equations have been generalized to include extra dimensions in an generally accepted form, or is it still under investigation? I've already read http://arxiv.org/pdf/hep-ph/0609260v4 but I didn't quite like the add-hoc assertion We assert that in all...

Recall that for a function f:A\subset \mathbb{R}^n\rightarrow \mathbb{R}^m, the derivative of f at x is defined as the linear map L:R^n-->R^m such that ||f(x+h)-f(x)-L(h)||=o(||h||) if such a linear map exists. We can show that for certain geometries of the set A, when the derivative exists...

Hi, I have a Mechanics vector problem here split in two parts. First to solve the magnitude of the resultant vector and then to give the bearing at which it's acting at. Worked out most of it, but the last answer to the question isn't the same as mine. Kind of difficult to explain the question...

I was told by my old physics teacher that there is proof (mathematically) for around 14 dimensions or something crazy like that. I think he said it was in relation to string theory and the amount of dimensions they need to oscillate as we think but seriously, we have x,y,z planes and time...

SU(3) needs to act on a minumum of 4 compact dimensions. SU(2) needs a minimum of 2 dimensions U(1) needs a minumum of 1 dimension Thus SU(3)xSU(2)xU(1) needs 7 extra dimensions. Because of this, string theoretists do not use the extra dimensions to generate the gauge groups, and they use...

Homework Statement Consider a Rocket in space, far removed from external gravitational influences, and suppose the engine starts up. As long as the engines are running, its instantaneous velocity v is a function of its mass. V is given by: V = A + B log(D/m) A, B, D are physical...

I have been reading about dimensions, and I understand that: A dot has no dimensions A line has 1 dimension A square has 2 dimensions A cube has 3 dimensions A tesseract has 4 dimensions And time is another dimension just like those In theory we can think of lines and squares, but we...

Hi All, Let's consider a Copper bulk material. This one can be reproduce (ad infinitum) by using a cubic unit cell (fcc) of lattice constant a. Let's cut this bulk along the (110) plane and expose the Cu(110) surface to the vacuum. My question is: which are the x and y dimensions of a (1x1)...

What do they mean by a dimension that's curled up? I'm having a hard time with this notion. What would such a dimension be like?

This has been bugging me for a while, but feel to tell me if it's a nonsensical or silly question.. Suppose there were 4 spatial dimensions instead of 3. How would we go about constructing the Pauli matrices? Assuming each matrix still only has 2 eigenvectors, we require 4, 2x2 mutually...

What will be the dimensions of temperature in a particular second, say the 10th?

Has anyone ever analysed Einstein's equations in 1+1 spactime dimensions? It seems to me like this would provide a convenient toy model for teaching or learning general relativity. For one thing the spacetime curvature can be visualized as curvature of a 2-dimensional surface.

Homework Statement 1. What is the meaning of Planck’s units? Hint: Compare the strength of the 4 fundamental forces. 2. Calculate the Planck’s dimensions as a function of the SI units. 3. What are the dimensions of the human being in terms of Planck dimensions?Homework Equations Plancks's...

Where can I get a list of standard sizes for I beams? (Preferably in SI units, just to save me time)

Homework Statement a Mess of 5kg is being hauled up a smooth invlined place at 30 degree to the horizontal with an acceleration of 1.5ms^-2 by mean of a string parallel to the incline: a) What is tension in the string Homework Equations Fnet= ma Rules of right angled triangles (SOC CAH...

Homework Statement Two masses A and B and of mass 1.6kg and 2.4kg respectively are connected be a light string which passes over a a frictionless trolley. Calculate: a) The accelaration of the 1.6kg mass. b) The tension in the string c) The net force on the 2.4kg mass d) The Kinetic Energy of...

[SOLVED] Motion in two dimensions question. At wit's end. Hi, I'll try to keep this short. I have a Physics exam tomorrow and was doing some textbook questions and can't figure out this one problem. It's killing me! I have the answer (supplied by the back of the book), but just can't seem to...

I am no expert in the string theory, but I was curious why it has so many dimensions. After thinking about it, I think I know why. It has to do with the assumption of 2-D strings. This can be understood with an analogy. We can make any color using combinations of red, blue and yellow. If we plot...

Homework Statement Write the difference between movement in one dimension and movement in two dimensions,also which are the different types for each of these movements Homework Equations The Attempt at a Solution

new to physics and my first question first,i am a nearly newbie high school student in physics, please i would like to learn physics from the internet enough to let me think ?...also i have a question in dimensions and please anyone explain how can you measure the 4d of matter although (i...

Hey I have two questions that I do not know how to answer...help? Please try to answer at a grade 10 level! And, this isn't a homework question. 1. A yard is to be enclosed by 40 meters of fencing. If all of the fencing is used, what dimensions will result in a yard with an area of 75m^2...

Homework Statement A plane flies a square route with each side 1500m in length (north, west, south then east) If a wind was blowing from the east at 20 km/h the entire trip, find the total time it will take for the plane to complete the journey, given that the plane is flying at 80 km/h...

I am currently part of a group (University) working on a project that is focused on designing a linac to find the Higgs Boson. I have a question about the the limiting factor for the tube/tunnel. Currently we have two considerations: 1) The thickness of the walls required to maintain the...

Apologies if this is the wrong forum, but I have a pair of thematically connected questions that I can't really fit anywhere else. Please move if this is better suited to the quantum physics forums. My first question being: The Poincare-Bendixon theorem states that chaos can only occur for...