Assumptions Definition and 111 Threads

Thought experiment: Alice, Bob, and the planet Zolan. Alice is floating in space 10 light seconds from the planet Zolan (Z) with a radio emitter and detector. She and planet Z are in the same rest frame. Bob has the same devices as Alice but is on planet Z. Bob then accelerates from...

I'm trying to reach a more thorough understanding of what's going on when we calculate equilibrium concentrations and was wanting to understand more what assumptions we make in order to follow through with the calculations. Let me ask off of an example: Consider mixing equal amounts of NH3...

Hi there, Consider a related rates problem, Gas is being added into a balloon at a rate of dE/dt = x ft^3/sec Find the rate at which the radius is changing at time h. This is a completely false problem; I am just giving an example. My question is, How would you know if there is a...

I've been figuring out the use of the nonparametric bootstrap and if I understand correctly, this is the procedure: 1. Take an original sample, a vector x = (x1, ..., xn) 2. Generate k vectors, each called a 'bootstrap sample', of the same length as x by random sampling (with replacement)...

I am currently working on an assignment using Tanagrams. I have the information that I have: • 2 large, and congruent, isosceles right triangles • 1 medium isosceles right triangle • 2 small, and congruent, isosceles right triangles • 1 square • 1 parallelogram The pieces can be...

So I started my first ever university course, at U of T. (It's a summer course.) The class textbook, which is called "An Introduction to Proofs and Problem Solving", should give you an idea of what the class is about. Anyway, the first thing that my Professor taught us is that you should never...

College sophomore here and just wanted to ask for an explanation of terms that I have come across in my math and philosophy courses thus far, but without direct teaching of them. I've seen these terms used in forum discussions and mentioned off-handedly by profs., but don't have a specific...

To prepare for a future physics course, I googled Newton’s Laws and then found about the Work Energy Theorem. I can see how Newton’s Laws makes sense but I don’t get why the kinetic energy formula is correct. The only experiment for the Work Energy Theorem I can find does not meet the...

Can someone please tell me if I have solved the problem? Is the math correct? Were the assumptions correct? Thank you in advance Homework Statement Show that: I(B) = 44 uA I(C) = 4.4 mA V(CE) = 1.2 V...

This isn't a homework problem - I'm just confused by something in a textbook that I'm reading (not for a class, either). I'd appreciate an intuitive clarification, or a link to a good explanation (can't seem to find anything useful on Google or in my textbook). My book states that one of the...

I would like to understand under what circumstances rate laws can leave out rate terms from certain reactions, in general, as a process of approximation. I am familiar with the basic method regarding the steady-state approximation already. Any books, websites or articles which are good or...

I have trouble understanding the mathematical arguments behind this view but I thought I would post it, in case anybody has any information/understanding/insights. The basic idea is that the mathematical assumptions on which the validity of Bell's inequality depends are that all the random...

Hello, Working through some reduction of order problems. I'm not sure about why the structure of a particular solution is assumed. Here's what I mean: Given y"-4y = 2 and a known solution is e^-2x, use reduction of order to find a second solution and a particular solution. Using a...

Assumptions 1) a=absorption 2) f=fission 3) ∅=neutron flux 4) time independent 5) group 1, fast neutrons 6) group 2, thermal neutrons 7) All fission neutron are boring in fast group 8) All neutrons created by thermal group, thus vƩf2 exists vƩf2 does not 9) Down scattering occurs but up...

Is there a Metric for the Sun and Earth other than the Schwarzschild Metric who has the Schwarzschild Radius on the interior of the body? What are the assumptions that turn that from GR to Newtonian? Rs(Earth)=8.87*10^-3m Rs(Sun)=2954m

It seems to me that classically physics is based upon the idea of measurement, that the length of a meter, the duration of a second, and the mass of an object is the same for one person as it is for another. Wheeler in his Geometrodynamics further was able to express mass and time in terms of...

The proof that 1/2+1/4+1/8+...=1 goes like this: X=1/2+1/4+1/8+... 2X=2/2+2/4+1/8+... 2X=1+1/2+1/4+... 2X-X=1+(1/2-1/2)+(1/4-1/4)+... X=1 The assumption that goes with this is that we can pair up the first term of X with the second term of 2X and so on without having the smallest term of...

I was recently trying to prove the variation of parameters formula for an nth degree equation, and I have come up with a question about the assumptions made during the derivation. During the derivation we assume that: u1'y1(k) + u2'y2(k) + . . . + un'yn(k) = 0 for k < n-1. It leads to the...

Homework Statement a stone is thrown vertically upwards with a speed of u metres per second. a second stone is thrown vertically uppwards from the same point with the same initial speed but T seconds later than the first. prove that they collide at a distance (4u^2-g^2T^2)/(8g) metres above...

I attached the problem and its solution. I was looking at this solution and got a little confused. Why did they say that "Assume that S = {v1, v2, · · · , vn} is a basis for V and c is a nonzero scalar. Let S1 = {cv1, cv2, · · · , cvn}. Since S is a basis for V , V has dimension n. Since S1...

Assume that we can expand the Helmholtz potential about T=T_c, M=0 in a standard Taylor series form of functions of the variables, A(T,M)=\sum^{\infty}_{j=0}L_j(T)M^j=L_0(T)+L_2(T)M^2+L_4(T)M^4+... Why A(T,M) must be even function of M? Coefficients can be expanded about T=T_c...

Hi How to be mathematically correct about assumption of independence about arrivals of clients at a bank? Physically I understand that there is no possible dependence between2 sequent arrivals of clients but anyway when I make this assumption I want to be correct according literature...

Hi people Newton's Second Law a=F/m assumes that either a body is pointlike or that force is transmitted instantaneously across it. Special relativity which applies to Newton's First Law and which was developed from the assumption of a finite velocity of energy transmission, has enjoyed...

Hey I'm taking a course which involves electrodynamics and i am currently reading about radiation. By expanding the relative distance between the current distribution r' and the point we're looking at r in a powerseries and assume that r' << r for all r' and r we obtain the vector potential...

Long story short I have an integral which is something like this: (in Mathematica code) Integrate[1/{(1 - b^2)*{((1 - y)*z + y)^2 + (1 - y)^2*(1 - z)^2} + 2*(b^2 + 1)*{(1 - y)*(1 - z)*((1 - y)*z + y)}}, {y, 0, 1} ] Written without assumptions. b is actually only in [0,1] and I think I...

What are the most general assumoptions for the derivation of Planck's law in quantum statistical mechanics: - thermodynamical equilibrium - non-interacting bose gas (photons) Do I miss anything?

It's been a while since I've done any work-energy questions, and I just noticed how vague some questions could be (or maybe I don't understand it that well). Anyway, suppose I have a box moving down an incline where the only forces acting on it are its weight, the normal force, and friction...

What are the Debye model`s assumptions for heat capacity or density of states? According to the einstein model we assume that N oscillators of the same frequency [ω][/o] and in one dimention. In three dimention N is replaced by 3N, there being three modes per oscillator.

Hi, An airline knows from past experience that the probability of a person booking a seat and then not turning up is 0.04. A small plane has 50 seats and 55 bookings are made. a) A binomial distribution is used to model this situation. What assumption must be made? Comment on how...

Homework Statement I'm having some issues coming up with a proof for |- (Box(P) ^ Box(Q)) -> Box(P ^ Q). Box is the unary operator for "necessary for". Homework Equations Axiom 1 A -> (B -> A) Axiom 2 (A -> (B -> C)) -> ((A->B) -> (A -> C)) Axiom 3 (~a -> B) -> ((~A -> ~B) -> A)...

Homework Statement I want to know how to set assumptions in Matlab. i want to integrate 3*a*x/b but i want to tell MATLAB that b is less than a. Homework Equations The Attempt at a Solution I know how to set assumptions that a variable is real/nonreal/positive/negative. eg...

In the course of proving that \sqrt{3} is irrational, I had another question pop up. To prove that \sqrt{3} is irrational, I first assumed 2 things: \sqrt{3} is rational, and the rational form of \sqrt{3} is in it's lowest form. I then broke the proof up into cases and showed that none...

I came up with my own design problem, after completing a refrigeration design problem on the completion of my thermo I class. My design problem is this: I want to accelerate air to 56m/s via a compressor and then a nozzle. I'm trying to do a cost analysis of how much power I would save if the...

Hi, All: The standard way of approaching the birthday problem, i.e., the problem of determining the number of people needed to have a certain probability that two of them have the same birthday, is based on the assumption that birthdays are uniformly-distributed, i.e...

I will refer to Griffiths' textbook Introduction to Electrodynamics, Third Edition. On page 70 he calculates divergence of E and implicitely assumes that divergence of rho is 0, where rho is charge density distribution. On page 223 he calculates rotB and says that rotJ = 0, where J is current...

Hi! As a part of a mathematical construction I used the rate of change of F(s) with s, i.e. dF/ds. F and s are smooth functions. The problem is that s(u,v,w) is a function of u, v & w and actually I need to find the rate of change of F with respect to u, v & w. The question is: what does...

To derive the blackbody spectrum, we set up the situation by assuming that a cavity is in thermodynamic equilibrium with a heat bath. My questions are: 1) Is the heat bath the black body? 2) Why is it called a blackbody? 3) Why does the cavity have to be in thermal equilibrium with...

In a lot of textbooks on relativity the Levi-Civita connection is derived like this: V=V^ie_i dV=dV^ie_i+V^ide_i dV=\partial_jV^ie_idx^j+V^i \Gamma^{j}_{ir}e_j dx^r which after relabeling indices: dV=(\partial_jV^i+V^k \Gamma^{i}_{kj})e_i dx^j so that the covariant derivative is...

In a linear elastic analysis using Abaqus CAE what assumptions does abaqus make of a simple truss structure. Cheers Gordon

I was wondering if it assumed the gas could not turn into a liquid?

So lately I've been digging into geometry and I always seem to come back to the same question, how can we really test to make sure our math values can correctly apply to world that we live in? First, let's assume that we live way back in time and our scale of measurements where limited (for...

Hi, In many statistics textbooks I read the following text: “A models based on ordinary linear regression equation models Y, the dependent variable, as a normal random variable, whose mean is linear function of the predictors, b0 + b1*X1 + ... , and whose variance is constant. While...

What are the major assumptions made by Bohr to explain atomic spectra from hydrogen? I had this on a test last week and was just wanting to know the answers. I was not required to answer it but am worried I will see it again. I looked through the book and can't find anything that is...

I was reading in a book, says \mu is a measure with compact support K in C, meaning \mu(U)=0 for U\cap K=0.. Is \mu(K) assumed to be finite in this case? It doesn't say in the book, but they make a statement which is true if that's so. Is there usually some assumption about measures being...

There are numerous lists online of the basic assumptions of science--too many for me to feel comfortable that there is actually a standardized consensus on this. Here is my question. What are the most generally accepted 'a prioris' of science? And how well do they stand up under careful...

The other thread here made me read up a bit on Bell, EPR, Aspect's and so on.. An important part is ofcourse the assumptions discussed intensively in the other thread. vanesch expressed my view about this: Why isn't it obvious here that the mistaken assumption is within quantum theory? Is...

when we derive the wave equation for a an o0ne dimensional wave moving at constant speed we assume that the wave move losslessly that is a plot of \psi(x,t) with x at any time t is same to the extent that one can be obtained from the other by translation. similarly what are the assumptions when...

Homework Statement I'm not going to write the full question as its not neccessary, but this is the gist of it. Electrons are fired at protons and a search is made for a neutral particle created in the impact. Both the electron and proton still exist after the impact, along with this new...

assume there's a road the cars have length of "d" m, and space btw them is "k", and are moving at "di/dt" and at some time, ahead of them is blocked trafic, and in there the cars moving @ "do/dt" and so i am analyzing portion of the road that has blocked traffic, like how many cars in...

I just read that string theory "started out as a generalization of quantum field theory where instead of point particles, string-like objects propagate in a fixed spacetime background". Is this true? And if so, did anyone try to do the same with a curved spacetime? What did they get? Or perhaps...