Properties Definition and 1000 Threads

Hi guys and girls, Just had a question I have been thinking about for a while. Suppose you have a sound maker than makes a pure tone at a particular frequency. You play this tone for an instant directed directly at a flat wall (not absorbent at all). If you could measure the reflected tone...

Does light intensity and brightness depend on amplitude?

I am working through an explanation of the wave function of the Hydrogen atom. I have got as far as deriving the version of Schrodinger's equation for the one-dimensional problem in which only the radial coordinate can vary: ##[-\frac{\hbar^2}{2m}\frac{\partial^2}{\partial^2...

If the abs(a+b) = abs(a) + abs(b), so the abs(z) = abs(x+iy) = abs(x) + abs(iy) = abs(x) + i abs(y). However, the correct wouldn't be abs(z) = √[x²+y²] ? √[x²+y²] ≠ abs(x) + i abs(y) => abs(z) ≠ abs(z) It's no make sense. What there is of wrong with those definions?

Homework Statement ##D_{ijk}## is an array with ##3^3## elements, which is not known to represent a tensor. If for every symmetric tensor represented by ##a_{jk}## $$b_i = D_{ijk}a_{jk},$$ represents a vector, what can be said about the transformation properties under rotations of the...

I find it strange that Aluminum is high on the activity series but does not react with evolution of hydrogen with many strong acids. I actually tried this when I was a kid. I had access to any acid or salt I wanted. I tried dissolving Al in H2SO4, HNO3, and HCl with no H2 bubbles. Aqua regia...

I understand that the centring of the Fermi energy at the Dirac point is a highly sought after property in Topological Insulators but I'm unsure as to exactly why? I see that the state at the conical intercept will be unique but I'm not sure of what is theorized to happen to the electrons...

Hi, Recently in class, my professor went over a relationship that exists between trigonometric functions, T(x), and their complementary functions. That is: ∫ T(x)dx = W(x) + C ∫ coT(x)dx = -co[W(x)] + C Without really providing a proof, we were told this relationship. I've plugged in numbers...

I read a textbook about limits. I saw several properties about the limits. $$lim f(bx)= b*lim f(x)$$ as x approach cThank you Cbarker1

Apologies for the break from format, but I'm not sure how to make this fit! I'm designing an experiment to compare the insulation properties of several materials. I would like to find the Thermal Conductivity (K) or the U (or R) values of these materials. However essentially all I am after...

http://www.cell.com/abstract/S0092-8674(13)01479-7

Hello sir, I am new to this forum i am looking for thermophysical properties of heavy water for my computer simulation. following properties i found in the wed. can anyone suggest me that these considered properties are correct (ref temp 40 C and 6.549 kPa) density = 1099.99 Kg/m3 specific...

Dear members, I'd like to collect those properties of "spin" that makes it different to a normal (classical) angular momentum or magnetic moment. Please help me, correct, reword my sentences one by one. I'd like to create a short but still understandable and correct list. 1. Spin quantum...

I know I am jumping ahead, as I am still working through part 1 of Spivak's Calculus, and am absolutely not properly equipped to prove his properties (if they are indeed provable). However, as I am trying to work on my proofing skills, my interpretation thus far has been, that these 12...

Is there any material,when made a hollow ball out of it & filled with lighter gas than air,will rise in air according to archimedes principle? But upon removal of that gas,it should not contract itself in volume like any balloon does...it should be able to retain its volume as it is even if...

Hello, I was given the attached 3 degree of freedom spring system with the purpose of analyzing it. I came up with the following equation of motion and then I ran Matlab to calculate the corresponding natural frequencies and mode shapes using eigenvalues and eigenvectors; I was asked to...

Homework Statement A deuteron is the nucleus of a hydrogen isotope and consists of one proton and one neutron. The plasma of deuterons in a nuclear fusion reactor must be heated to about 300 million K. (a) What is the RMS speed of the deuterons? Is this a significant fraction of the speed of...

Homework Statement If A is a 2x2 matrix, then det (2A * adj(A)^-1) = ? Homework Equations Adj(A)A = det(A)I The Attempt at a Solution First, I separated them so it became det(2A) * det (1/ adj(A)) Then taking the 2 out, and it becomes 2^2, so 4 det(A) * det(1/ adj(A)) adj(A) =...

Homework Statement For what values of k is (scalar product of vectors a and b) = a_{1}b_{1}-a_{1}b_{2}-a_{2}b_{1}+ka_{2}b_{2} a valid scalar product? The vectors a and b are defined as: a = a_{1}e_{1} + a_{2}e_{2} b = b_{1}e_{1} + b_{2}e_{2} where e_{1} and e_{2} are unit vectors...

Do you know why it's important for rubber to be resilient? and does anybody have an example of an object that is made out of rubber which must be resilient? and does anybody know why it's important why tires and children's play grounds are made from resilient materials? Many thanks,

Hi, I'm doing one of my physics HL coursework's (IB) on the behaviour of electric putty when conducting electricity. My teacher can't explain to me what electric putty actually is and I can't find it on the internet, so could anyone tell me if the conducting properties of electric putty are...

Homework Statement Hey everyone, So I've got to prove a couple of equations to do with the Levi-Civita tensor. So we've been given: \epsilon_{ijk}=-\epsilon_{jik}=-\epsilon_{ikj} We need to prove the following: (1) \epsilon_{ijk}=-\epsilon_{kji} (2)...

I know what is lattice constant but it has been given that nano particles have reduced lattice constant due to huge fraction of atoms being in surface. How come the lattice constant of nano particles reduced due to high number of atoms present in surface? Why do the surface area, hardness...

Homework Statement Let S ⊆ R be such that (i) a, b ∈ S ⇒ ab, a + b ∈ S (ii) for all x ∈ R exactly one of the following holds x ∈ S, x = 0, −x ∈ S. Show that S = {x ∈ R ; x > 0} (the set of positive numbers P) 2. Relevant theorems (T1) a² > 0 ∀ a ∈ R. (So a²∈P) (T2) All positive...

Homework Statement You and a friend each have one rope. You tie the two ropes together and stand as far apart as possible, each holding one end of the new longer rope and pulling to put it under tension. You then begin moving your arm in such a way as to produce a harmonic wave with a...

What do physicists think about water as an example of something with emergent properties? I wonder if the concept of emergent properties has become main stream in modern physics. If so, what happened to reductionism? Does this go for water?

Homework Statement 1. Let ##p(x) = a_{0} x^{n} + a_{1} x^{n−1} + ... + a_{n} , a_{0} \neq 0 ##be an univariate polynomial of degree n. Let r be its root, i.e. p(r) = 0. Prove that ## |r| \leq max(1, \Sigma_{1 \leq i \leq n} | \dfrac{a_{i} }{ a_{0} } | )## Is it always true that? ## |r| \leq...

Are different electrical frequencies allocated to specific applications because of their properties or to regulate the spectrum so that each assigned frequency range is unique to one entity? I guess a related question is: Are we going higher in frequency ranges for things like automobile...

Hey, Ive a question in my textbook and I don't really know what to do! The question is: I know I need to prove that the relation is 1)Symmetric 2)Reflexive 3)Transitive But how do I prove this

Homework Statement I've solved a problem in my engineering homework to a point where I have the following data: ψ = arctan(3) = 71.57 (degrees) , inverse tangent of 3 δ = 30 degrees solve for gamma and chi (χ): tan(2gamma) = tan(2ψ)cos(δ) sin(2χ) = sin(2ψ)sin(δ) Homework Equations...

Homework Statement Use the Poisson distribution W=(λ^n/n!)*e^-λ to calculate <n> Homework Equations <n>=ƩW*n The Attempt at a Solution Since W = (λ^n/n!)*e^-λ I wind up with <n>=[(λ^n/n!)*e^-λ]*n But I really don't know where to go from here. Should I do a Taylor Series. I've...

I want to circulate cold water through copper tubing curled in a spiral about a fan. I'll cool the water with a large block of ice that I can remove and replace like a battery. To avoid making a mess I can freeze the ice inside of a copper housing, and pump the water in copper tubes around that...

Problem: Let $O$ be an $n \times n$ orthogonal real matrix, i.e. $O^TO=I_n$. Prove that: a) Any entry in $O$ is between -1 and 1. b) If $\lambda$ is an eigenvalue of $O$ then $|\lambda|=1$ c) $\text{det O}=1 \text{ or }-1$ Solution: I want to preface this with that although this is a 3-part...

Hi everyone, I'm trying to find a function of single variable f(x) with the following properties: -It is symmetric around zero -It is differentiable everywhere -f'(x)≥0 for all x>0 -f'(x)=0 when x=0 -f'(x)≤0 for all x<0 (I think these last two actually follow from the first three?)...

Hi, I am sort of hung up with a particular step in a derivation, and this has caused me to ponder a few properties of partial derivatives. As a result, I believe I may be correct for the wrong reasons. For this example, the starting term is (\frac{\partial}{\partial x}\frac{\partial...

I have written a short paper that addresses the question posed in the title. You can find a copy of the paper here: http://www.math.csusb.edu/faculty/pmclough/LP.pdf. I think the paper may have some pedagogical value. If you have any comments or suggestions regarding the paper or any different...

Three objects (A, B, and C) are brought close to each other one at a time. A and B attract, but B and C repel. Simple true/false question involving "is this one positive/negative/etc." What I'm unsure about is whether or not A could possibly be neutral, or more specifically, is there any way to...

Homework Statement Prove the following properties of relations: 1) If R is asymmetric then it's antisymmetric. 2) If R is asymmetric then it's irreflexive. 3) If R is irreflexive and transitive then it's asymmetric. The Attempt at a Solution 1) If R is asymmetric on a set X, then for all...

1.show that there is no axiom for set union that correspond to "Existence of additive inverses" for real numbers, by demonstrating that in general it is impossible to find a set X such that $A\cup X=\emptyset$. what is the only set $\emptyset$ which possesses an inverse in this sense? 2. show...

I'm interested in solutions of an equation f'(x) = -\frac{xf(x)}{Af(x)+ Bx^2} with some positive initial value f(x)>0, and with positive constants A,B>0. First question: Does an explicit formula exist? I couldn't figure it out. Second question: I see that f(x)>0\implies f'(x)<0, and on...

When a particle decays into two different particles, they are said to be entangled. If one of these is absorbed by an atom or there is a subsequent interaction with another particle, what happens to the previous or initial entanglement? Does it diminish or completely go away? For example...

Hello, Quick run-down: I am attempting to model thin film materials (e.g. Ti-Al-N) for thermal analysis. I am confused on how to figure out the number density of Nitrogen for a ceramic. All the tables I have in school textbooks are for gas (~0.0013 g/cm3). I can find density of...

in the following exercises, assume that x stands for an unknown real number, and assume that $x^2=x\times x$. which of the properties of real numbers justifies each of the following statement? a. $(2x)x=2x^2$ b. $(x+3)x=x^2+3x$ c. $4(x+3)=4x+4\times 3$ my answers a. distributive property b...

please help me break down this computations into the simplest possible steps using properties of real numbers. a. 5+37 b. 6*17 c. 12*16 d. 64+55 i'm not quite sure where to start.

Its been a while since I've done this stuff, and I don't have a text handy. I know that for sets, intersection distributes over union, I don't remember if the same will hold for vector spaces over addition? for example does A \cap (B + C) = A \cap B + A \cap C

Hello, I want to know what factors determine that a signal (radio wave, microwave, infra red) cannot be use for broadcasting but only point to point communication. I know that it has to do with frequency and the energy associated with it but cannot seem to have a concrete reason because of...

I have the following vector field:E=E_0(-sin(\phi),cos(\phi),0)^T and [/itex]E_0[/itex] is some constant. Does anybody here have an idea what this electric field does to a metallic sphere that is in it? Thereby I mean, does it create a dipole moment or does it create a current and so on?

justify each of the steps in the following equalities. i don't know where to start. what i know is i have to use properties of real numbers. please help! 1. $\displaystyle \left ( x+3 \right )\left(x+2\right)\,=\,\left ( x+3 \right )x+\left ( x+3 \right )2\,=\,\left ( x^2+3x \right )+\left (...

can you give an example of symmetric property of equality and transitive property of equality. the generalization of these properties are a bit abstract for me. thanks!

Hi, I'm wondering if there's any possible way to do voltage gating to a sample while observing it with a microscope, in order to measure its optical properties while changing its electrical parameters. Thanks