Pure Definition and 482 Threads

How to get pure DC from an ac whose voltage or amplitude is increasing by time until it reaches a particular fixed value and then drops to zero

I am following Vaidya metric and how it is related to pure radiation from Wikipedia. But when it reaches the line where stress-energy tensor is equated to product of two four-vectors, I cannot follow from where they are assumed to be null vectors, and why if the stress-energy tensor is given in...

I recently had a discussion with someone about Quantum Mechanics. His story was confusing to me but I could detect that he made an error in his thinking which I proceeded to explain : You are trying to reason from the idea that the 'collapse of the wave-function', which precedes the...

First of all (and I know this is not the place I'm supposed to introduce myself,) I'd like to say hi to the forums. Now onto my question. For the past few weeks, I've been thinking about an idea I had. That idea was to use pure oxygen to oxidize a combustion reaction in an engine. I'm sure...

I understand why an impure solid will have a decreased melting point, however, in my recent organic chemistry lab section I mixed two finely ground pure solids together and observed that the mixture melted at a lower temperature than either pure solid. I understand this in principle, but...

Homework Statement A solid sphere of radius R is set into motion on a rough horizontal surface with a linear speed v0 in forward direction and angular speed ω0##=\frac{v_0}{2R}## in counter clockwise direction. Find time after which pure rolling starts. Homework Equations For pure rolling...

Hello, I am really struggling to write a math formula that I need for my website plugin. A=(Length) B=(Width) C=(Square Inch) A*B=C 0<=C<=16 then C*.84 17<=C<=34 then C*.70 35<=C<=65 then C*.56 66<=C<=99 then C*.42 100<=C<=150 then C*.35 151<=C<=500 then C*.31 I wrote this formula in excel...

In psychrometrics it is outlined time and again that we cannot achieve a pure humidification process i.e, add only moisture to unsaturated air without a change in its Dry Bulb Temperature(DBT).While pondering over the idea I came up with a possible way of doing it (if it is correct at all) and...

As a fresh pure math phd student, I aim to become a mathematical physicist, and currently I try to schedule out what I should do step by step in this four years on phd program. But in my university, there is no professor in this field could help me as my advisor. So I wish to get some advice...

Can pure* water be made to fluoresce if illuminated by some particular frequency of Ultra-Violet light ? [* No chemicals added ]

I am trying to find the theoretical power required to compress nitrogen from a pressure P1 to P2, as well as the final temperature T2 after compression. I found no formula that were anywhere near complete, but I found this tool, which tells me that from 300K@1Bar, I need 271.4kw (271kj/s) to...

I use to hate math during high school. However some eight years after graduating and being in the military help with my attitude towards math. I am reviewing a GRE math review book and I haven't been able to put it down. I just learned quadriatic equations and am pursuing into intermediate...

Studying the production of the bound state of ##μ^+μ^- ## in the scattering experiments of ##e^+e^-## at electron positron colliders ##e^+e^-\toμ^+μ^- ## via ##e^+e^-\to 2γ\toμ^+μ^- ##. This bound state further can decay into ##e^+e^-## or ##2γ##. I am confused about the vertex ## 2γ\toμ^+μ^-...

I am planning to study the following pure mathematics areas (on my own) and wanted to know if this is the best sequence: 1- Formal Logic 2 -Philosophical Logic 3- Sentential Logic 4- Predicate Logic 5- Symbolic Logic 6 -Set Theory 7 -Pure Mathematics (Intro, Pure Math I and II and Hardy) -...

I was just wondering what people thought about this program. I know a couple of kids who are graduating with their M.S. in pure math from DePaul and they are going to university of Oregon and Toronto for the phd's.

Hello. I am in desperate need for advice. I have searched for advice everywhere and each time failed to obtain it. This is my last resort. Please help me and bare with me while I explain the problem. I am 28 years old guy. I have literally whole day free to pursue whatever goals I see fit...

when a sphere starts moving with initial velocity ##v_0## and zero angular velocity in a plane surface having friction, then first it will start rotating till it starts pure rolling. that is, its velocity of centre of mass will decrease due to backward friction and angular velocity will increase...

This is a self-assigned question. Not homework. I may have the right answer, but would like some reviewing. It came to me while reading on a CS topic, this did not come from a math textbook, otherwise it would be slightly more in context. I did not use any formula (so 2 would be empty) and 1...

Is it possible, in principle, for an experiment to distinguish between an ensemble of pure states and an ensemble of mixed states? If so, how? In particular, I am thinking of an ensemble of particles whose spin has been measured, one at a time, on the "Vertical" axis. The ensemble consists of...

Hi, I'm hoping someone here can shed some light, I'm currently in my 3rd year of my Physics degree and have discovered I really don't have the mind to memorise / reproduce paragraphs of text. Even if I understand the concepts it takes me a LONG time for my brain to take text in. Maths however I...

If a drill bit that was cut out of a single large diamond were made, would it last forever, assuming it was never used to drill through diamond and was never exposed to a laser? Would it ever get dull or break?

Hey, I have a question for evaporation--What is the real driving reason for evaporation? I usually believe that it is a pure diffusion process: the saturated pressure of liquid at the liquid vapor interface is higher than the partial pressure of vapor in the ambient, and this pressure difference...

i am trying to find the pure bending moment of this beam 1. Homework Statement simply supported solid beam 3m long W=100mm D=200mm with a UDL of 2tonnes/m and a point load in the centre of 200N Homework Equations is the pure bending moment at the peak of the bending moment diagram i have...

The short question: For the current state of a given system, is there a way to determine whether the state is pure or mixed? Of course, one can take as many ensembles as you need, do as many experiments as you need, and determine where the state sits in the entire state space. However, I find...

Hi guys. I had a question concerning a pure proton plasma with a given temperature and its loss of energy due to the Stefan-Boltzmann law. From my understanding, the Stefan-Boltzmann law applies to objects that contain electrons. I don't think that's true but I would like to know if it is. If...

Hello All, In this recent Navy publication, a team of researchers said they have discovered cusp confinement. This could be a major step towards fusion power. I am working on a write up of this publication. I am trying to understand their inferometry data. As far as I can tell, the...

Hi all, So I'm finishing my first year in college and I did Calculus(based on Stewart). However, I don't feel I learned a lot during this year. There were not many proofs, the only proofs I studied was induction and contradiction(and some proofs in Stewart). I honestly do not like the book at...

PROBLEM: Show that Special Relativity predicts a precession of π(GMm/cl)2 radians per orbit for any elliptic orbit under a pure inverse-square force. where G is gravitational constant, M is mass of larger body, m is mass of smaller orbiting body, c is speed of light and l is angular momentum...

Considering the majority of the universe is intergalactic space and that light gets dimmer by the inverse square law. If you pick a random place in the universe you are going to see no light (Light that's bright enough for the eye) and hear no sound. Is this accurate to say?

Hey guys! Let me throw in who I am before I introduce my question. I finished my year of graduate school last May, figured out an advisor and a field (something related with Brownian motion on manifolds), and I'm overall happy with it all. No plans of dropping out, I enjoy the company of my...

It is well known that when the vapor pressure of a substance is bigger than the external pressure, it boils. In vacuum there are no particles and therefore no pressure, shouldn't therefore, even diamond as for example, boil in complete vacuum?

Hi guys I'm here to ask the age-old question, namely, I am thinking of transferring from my highly ranked university where I finished my first year in an Engineering Physics type program to the university in my hometown where I want to study Pure Math (it is too late to transfer faculties at my...

I'm a third year physics student and I can't decide between computational-based physics and plain physics. I've taken a few programming courses and have been programming as a hobby since I was around 12. I originally wanted to do a lot of math and physics to apply it to programming for graphics...

Hi there, I need to choose my major in a week and it's between physics or astrophysics. Most of the courses are the same except a few: The different courses: Physics: statistical mechanics, solid state physics, and nuclear and particle physics Astrophysics: Intro to astro...

The definition of species is "a group of organisms that can interbreed with each other". So, how is interbreeding of two dogs of different species, say a german shepherd and a pitbull, possible? And the concept of a "pure" and "impure" breed - how will you explain it? As according to the...

Hello guys, Homework Statement the problem goes as follows: "Which measurement should you do on a statistical ensemble of qubits in order to distinguish between the pure state |Ψ>= cos(θ)|0> + sin(θ)|1> and the mixed state ρ=cos^2(θ)|0><0| + sin^2(θ)|1><1| " Homework Equations I am not...

Hi everybody! I was wondering how much importance there is in studying pure math, for the budding theoretical physicist? mathematical physicist? Also I was wondering whether a mathematical physicist would work more on mathematical methods that physicists can use or do work like Einstein...

Is it true that there always exist a unitary matrix that can take a state vector of an arbitrary pure state to another arbitrary pure state ? (of course assuming same hilbert space). If true, how do we prove it ? it look like it is true via geometrical arguments but i have not been able to...

I have been offered admission by St Johns College Cambridge University for Natural science. In the first year I have to choose 3 experimental sciences along with maths. My options are physics, chem, materials science, computer science and some biological options. I am looking into a career in...

Hello, I've just been accepted and will begin as an undergraduate in physics this fall. I'm planning on taking classes, in addition to the required courses, concentrated in particle physics, QM, field theory, etc. Also, I took courses on Set Theory and Topology, and fell in love with what I...

Hello, Due to all the buzz by Mars One, my friend and I have been discussing hypothetical possibilities for long term colonization of Mars. He suggests the only long term solution is to extract O2 from the Ice on Mars and give the planet a breathable atmosphere. he did the math and calculated...

Suppose we heat a pure substance in solid phase at a constant pressure corresponding to it's triple point data up to it's triple point temperature where all the three phases of the substance are known to exist in equilibrium. Will further addition of heat at the same pressure result in...

Hello, 1. I am puzzled about which to be : theoretical physicist or pure mathematician ! what should i do ? 2. If i decided to be a theoretical physicist : should i study some pure maths to make new theory in physics ? Like general relativity : the maths used on it was before it a pure maths...

I believe this is an error minimization problem so I am trying to solve the following equation Min((∑ ( (S(t) - A cos(b t + C)))^2 ) Where S(t) is the input signal, t is time and I will sum over t, A is the amplitude, b is radians per second (frequency), and C is the phase angle. I...

this probably is a wrong section but i did not know where else to put it (feel free to move it to where it belongs). that said could someone recommend me a pure math linear algebra book? preferably with LOTS and LOTS of examples! i think i have decent grasp of the basic theory but i have been...

Hello All, I've been searching for days to try and solve this but I'm going round in circles so thought I'd fire it out to into the ether! I'm analysing a gantry system that is essentially cantilevered from one end but the part of the problem I'm struggling with can be simplified thus...

There are the famous experiments, which show, how an Oxygen soap bubble gets attracted by a magnet due to it's paramagnetism. And how a Nitrogen bubble gets repelled by it (in air)But how does one calculate the attraction force of this pure Oxygen soap bubble in air due to a magnet. I'm Sorry...

I just started number theory, and I feel completely lost. I never did proofs in calc. I am used to watching the professor do examples, then with solutions manual at home see how the problems are done and use the manual if I get stuck. This book on NT has no homework problems or solutions. I just...

This is how one poster tried to explain it to me but for people who have only taken a basic physics course in college it leaves a lot wanting. "If a system is in a pure state, and you know what the pure state is, then your knowledge of the system is complete, and all uncertainty is quantum...

Homework Statement Suppose a wheel with radius R is resting on a non-inclined surface. A torque \tau is applied to the wheel center. In an attempt to prevent wheel from spinning, the ground applies a static friction force to the wheel at the contact point (parallel to the surface), then the...