Difference Definition and 1000 Threads

Summary

This is probably a silly question, though it's confused me a little so I thought I'd ask. It is my understanding that a function is loosely defined as a mapping between two sets, whilst a variable can represent an element of either of those sets. I'll take the example of velocity, since it's...

How did you find PF?: Google search How we can differentiate failure and fracture using Stress Strain Curve [Mentor Note -- thread moved from the New Member Introduction forum]

We have defined lipids as"molecules which are insoluble in water"then why don't we consider polysaccharide as lipids as polysaccharides are insoluble in water and also on the basis of what these biomolecules are classified, We say that carbohydrates are polyhydroxy ketones/aldehydes and lipids...

Hello! I have some data points obtained from a measurement and one of them is defined as the reference point. I need to compute the difference between that reference point and all the others (including itself) and plot the difference as a function of another variable (which doesn't have an error...

(NOTE: I have had a few similar postings lately on this subject, but they were much broader in scope, so I am posting only for this particular case; everything else has been figured out.) If given that limx -> a f( x ) = +∞ limx -> a g( x ) = +∞ what is the epsilon-delta formulation for...

Sometimes I see people saying that a material is strong and stiff and ... What is the difference between strong and stiff in the chemistry sense? Could it be strong but not stiff or stiff but not strong?

So to do this problem I need the relevant formula for phase difference which is this: I first need to find wavelength and this is lambda = velocity/frequency So lambda = 257/641 = 0.40093603744 m Hence phase difference (in radians) = 2pi * (2/0.40093603744) = 31.3 rads My concern is that...

You often hear this debate about the role of the observer in Quantum Mechanics. How you view this role is usually dictates the interpretation you prefer. If it's Copenhagen, then the observer is more robust and plays a crucial role in wave function collapse. If it's Many Worlds, then the...

So for my scheme I obtained ##\frac{\mu}{h^2} U_{p}+(\frac{v_{1}}{2 h}-\frac{\mu}{h^2})U_{E}+(\frac{v_{2}}{2 h} - \frac{\mu}{h^2})U_{N} - (\frac{v_{1}}{2 h}+\frac{\mu}{h^2})U_{W} - (\frac{v_{2}}{2 h} + \frac{\mu}{h^2})U_{N} + \tau = f## however I am not sure this is correct. I am quite new to...

V at surface = k Q / r = 9 x 109 x (1 x 109 x (-1.6 x 10-19) / (1 x 10-2) = - 144 V V at a point far away = 0 V From the sentence "electric potential difference between the surface of this sphere and a point far away" means that the question asks about V at surface minus V at far away so the...

Hi all, I have ran into some confusion about the equivalence principle; perhaps I should state what I understand and then proceed to ask questions. It is my understanding that the equivalence principle states that spacetimes are locally Minkowski, and so the rules of SR apply in that locality...

Right now we are learning about the Lewis definition of acids and bases. I don't get the clear difference between co-ordinate covalent and ionic bonds. For example, AlCl3 is listed as a co-ordinate covalent bond because experiments show that it behaves like a covalent molecule. Why can't it be...

Hello everyone, I have been pondering on the behavior of the E field in conductors. In electrostatics (where the charges are not moving): a) Electric fields are time- independent but position-dependent b) Electric fields are always zero inside a charged or uncharged conductor. At the...

I read the chemical formula for Potassium Hydroxide (Caustic soda)=NaOH (1)I also read the chemical formula for caustic potash having same chemical name Potassium Hydroxide =KOH. I want to know what is the difference between these two chemical compounds in terms atoms, molecules, ions? Why...

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My notes seem to imply this should be obvious : If i consider the covariant deriviative then i get something like christoffel= nabla ( cov derivative ) - partial So difference of two of them will stil have the partial derivatuves present ,assuming these are labelled by a different index ...

What is difference between subgroup and closed subgroup of the group? It is confusing to me because every group is closed. In a book Lie groups, Lie algebras and representations by Brian C. Hall is written "The condition that ##G## is closed subgroup, as opposed to merely a subgroup, should be...

I know this topic was raised many times at numerous forums and I read some of these discussions. However, I did not manage to find an answer for the following principal question. I gather one deals with the same set in both cases equipped it with two different structures (it is obvious if one...

Special Relativity explains that there is no universal reference frame, all observations are relative. So a traveller departs on a return jouney on an aircraft and finds on return that his/her time has slowed down relative to a person who remained on the ground (this is tested fact). But...

Hello all I was wondering someone could help clear up my understanding about the difference between Absolute and Gauge Pressure. After some reading i have been told that the Absolute Pressure is pressure taken at 0 relative to a vacuum. I am trying to understand what this actually means...

Me and some colleagues discussed accuracy of measurements. We didn't agree on how to treat the accuracy if two values are used to find the value, i.e. the difference between two values. Situation (explanation) The weight of a mass m of approximately 5 μg is to be scaled. The scale has an error...

See fig(a), S1Q=7lambda S2Q=9lambda I think since source S2 is lagging behind. So, we should add the phase 4pi instead of subtracting it from the cosine function. Wouldn't subtracting the phase further delay the wave more.

This is the work I've done so far... I=p^2/2dv...I=(10)^2/2(1.2)(343)=.12112 I(A)=P...(.12112)(4pi(500)^2)=380522.366 I=P/A...380522.366/4pi(4000)^2=.0018925 10log(I/I0)...10log(.0018925/10^-12)=92.77db 92.77-7(4)=64.77db I am winging it and that's the closest I can get to the right answer...

#Code nr.1 x=[1,2] def double(l): return [a*2 for a in l] double(x) print(x) #Code nr.2 def f(x): x[0]=x[0]+1 return x x=[3] f(x) print(x)

I am working out an example problem from one of my textbooks and I am a bit confused on why a value is negative. The problem asks: Calculate the final speed of a free electron accelerated from rest through a potential difference of 100 V. This is a conservation of energy problem. Ultimately you...

Imagine a container of salt water at 0V (Relative to ground),Now you've put in it 2 electrodes,one at +500V (Electrode A), The other at +250V(Electrode b), Normally positive ions should go to the negative electrode , and Negative ions should go to the positive electrode , But in our example the...

What is the difference between electrodynamic suspension (EDS) in maglev trains and quantum levitation? I'm having trouble distinguishing the difference between both.

and when are they the same thing? In quite simple terms.Many thanks

I've been thinking about this from time to time, I'll try to make this short and understandable. So we go back to the early universe within our current best model of extrapolation called the Big bang theory. In the early universe as it was expanding we have a very dense and energetic matter...

What is difference between 1. kind Cristoffel symbol and 2. kind Cristoffel symbol? Is the Cristoffel symbol in ricci curvature tensor 1. kind or 2. kind?

I saw there are two types of methods for RF imaging, Inverse Scattering" and "Diffraction tomography. What are the differences between them?

Hello, I'm slowly getting crazy about this stuff. I'm trying to understand what are thermal inertia/effusivity and information have been incoherent so far. The best example of that is seen on wikipedia where the only mention of thermal inertia is in the article...

What is the difference between those horns/waveguides and regular metal pieces with a same geometry? Why the microwave companies sell those parts at hundreds and thousands dollars? Why we cannot buy some metal sheets or pipes on McMaster-Carr with very low price and make some microwave...

I'm not really sure what I need to find exactly. From what I'm seeing, I could give C1 the max potential difference of 125V because it has the lowest capacitance, and because V = Q/C, this means the capacitor with the highest potential difference across its plates will be the one with the lowest...

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Hi everyone, While finding the solution for one of my exercises, I found the following answer. I'm seriously questioning if the equations provided in that answer are reversed. According to my understanding, if two vectors ##\vec{S}## and ##\vec{T}## are parallel (same direction) the magnitude...

Hello everybody, Im confused with the difference of the both coupling phenomena, is it just the difference in the amount of electron? So spin-orbit-coupling is just the coupling between orbit and spin of one electron and the russel-saunders is the coupling of a spin of many electrons and the...

I feel confused about proving the two terms are idempotents.

I always read that the static friction applies when the object is not moving. If it starts moving then you have kinetic friction. But suppose the case of a block on conveyor belt. The block is moving, but I was told that that friction was static friction. Or suppose the Death Wall. I've also...

I find λ first and I get λ = 3/10 m phase difference = ##\dfrac{2 \pi (1) }{\dfrac{3}{10}} = 6.7 \pi## Answer key = B What is my mistake? Thanks

Firstly, I'm given this complicated circuit as shown below. What I have to do first, is to simplify it, which I will need help in checking. One question here: It's not possible to simplify this by adding resistors in series and capacitors in series am I, right? Or is it possible in this case...

Can a photon with energy greater than energy level difference of atom be absorbed by atom?Is there any case in that photon share a part of energy for atom and keep other part of energy for itself?

Where does energy come from in potential difference appearing in Hall effect?It is magnetic force causes this potential.But we know that magnetic force does not do work on motion charge particles, then where is the energy come from?It seems contradiction that magnetic forces cause the potential...

I was recently working on a problem of Griffiths and in the solution's manual it used an argument to solve a diffential equation that caught my attention. It said that it would look first to the steady state solution of the ODE. I tought "All right, I get that" but when I got to translate the...

My question is all in the context of this paper. I have problems understanding a definition and a method. Sina, C. et al. Mitochondrial gene polymorphism is associated with gut microbial communities in mice. Sci. Rep. 7, 1–9 (2017). This is a segment of the introduction: " Since common inbred...

Hi guys, I'm trying to understand between gyroscope angular displacement and euler angles? for example { Δx = Δx + h * Rx * SCx);} this is gyroscope output about anguler displacement.This value can be used to determine angle that device created.Why we should euler angles to fly.(I know...

I have a 4D array of dimension ##100\text{x}100\text{x}3\text{x}3##. I am working with `Python Numpy. This 4D array is used since I want to manipulate 2D array of dimensions ##100\text{x}100## for the following equation (it allows to compute the ##(i,j)## element ##F_{ij}## of Fisher matrix) ...

Hello. Could you please explain to me what the difference is between quantum computers and quantum accelerators?

These quantities are evidently not equal unless v1 = v2, but surely the change in kinetic energy should be the same in different frames of reference? I was wondering what mistake or misconception I have made because this has been bugging me for a little while. Thank you in advance!