Mean Definition and 1000 Threads

Homework Statement a 6.57g sample of NiSO4*6H2O (molar mass 262.84) is dissolved in enough water to make 50.00mL of a green solution and 7.15g of Na2CO3*10H2O (molar mass 286.14) is dissolved in enough water to make 50.00mL of a colorless solution. The two solutions are mixed and a green...

Hi! I search the way to calculate the average orbital kinetic energy like is given in :http://physics.nist.gov/cgi-bin/Ionization/bun.php?Id=AlI (here is for aluminum). I would like use the underlying method to calculate the average orbital kinetic energy for the silicon (Si) element. If you...

Homework Statement Hello! I am trying to compute the bi-geometrical mean on data that contains negatives. But before that I wanted the test the formula that accounts only for positive values using the sum of their logarithms. By doing so I don't get the result I compute by using the "usual" geo...

Emily and Ashli each collected six rocks, and the masses of the rocks are shown in the table below. The mean of the masses of the rocks Ashli collected is 0.2 kilogram greater than the mean of the masses of the rocks Emily collected. What is the value of ‘x’ ?

Homework Statement Hi guys, I am working on a 'daisy world' lab for an environmental systems class. I will share the lab link as it is free: http://www.gingerbooth.com/flash/daisyball/DaisyBall.html Essentially, we focus on a very simplified world where the world is either barren soil or white...

A quantum mechanical oscillator with the Hamiltonian H1=p^2/2m +(m(w1)^2 x^2)/2 is initially prepared in its ground state (zero number of oscillatory quanta). Then the Hamiltonian changes abruptly (almost instantly): H1→H2=p^2/2m +(m(w2)^2 x^2)/2 What is the mean number of oscillatory quanta...

Homework Statement Which of the following is closest to the mean distance between air molecules at room temperature and pressure (298 K and 101325 Pa)? Assume air is made of 79% N2 and 21% O2 by moles. A 0.4 nm B 4 nm C 40 nm D 400 nm E 4 μm Homework Equations PV = nRT The Attempt at a...

Hi everyone in an article they mentioned that the amount added of a product is given by molecules/nm² how can i obtain a molar or mass concentration from it ? best regards

Homework Statement For the first half of a trip a car has velocity v1; for the second half of a trip it has velocity v2. What is the mean velocity of the car? (The book does not mention a direction.) Homework Equations Arithmetic mean: $$\frac{v_{1}+v_{2}}{2}$$ Harmonic mean...

What does it mean when a limit is finite

Looking at relativistic transformations and suddenly we have this transformation matrix with an upper and lower index. See below: A bit of googling tells me the upper index means a co-ordinate. However I'm not sure what the lower index is. Overall I have no idea what makes it so special, or...

... the exact opposite of its dictionary meaning? a means not synchronous means happening, existing, or arising precisely at the same time (https://www.merriam-webster.com/dictionary/synchronous) So if I have two lines like double d = Math.Sqrt(5.0); string s = new String('f', 1239)...

Homework Statement Suppose that x,y are in (0,0.5). Show that: $$\left|\frac{1}{x^3}-\frac{1}{y^3}\right| ≥ 48|x-y|$$ Homework EquationsThe Attempt at a Solution I think that we need a function ##f(t) = t^{-3}## & ##f'(t) = -3t^{-4}##. Now we use the MVT here to show that there is some c that...

If yes, because graphene has infinite effective mass, has it infinite mass as well? http://physics.stackexchange.com/questions/52125/effective-mass-and-fermi-velocity-of-electrons-in-graphene

In our section on path independence, we were asked to find the potential function given a vector field. Our teacher says to use only line integrals to find the potential function, and not any other method. Like if we have ##F=\left< M,N,P \right> ## The first step is to determine if the domain...

I am building a business cycle index, which include 4 variables that drive the index. Each variable I also include autoregessive coefficients that are all significant and negative. I was wondering what is the significance of this? In other words, what is the significance of have autoregessive...

Homework Statement I'm trying to formulate a formula based on an experiment I did. Homework Equations The Attempt at a Solution [/B] where x_1 = mean (one of 5 mean values) x_i = value of variables (there are 4 of them added together) n = number of variables My problem is, for the left...

Hi. I have a rather silly question. When speaking about a single photon? What do people mean when they speak of the polarization of a single photon. For instance, in classic electromagnetic theory, this would be the direction in which the electric field of the wave is oscillating . But does...

My book says that a free neutron, unlike a free proton is unstable. It decays into proton, electron and a antineutrino, and has half life of about 1000s. I do not understand how a single particle can have something called half life. I am finding difficulty to think of a proton being reduced...

What does the N^2 mean in this case? (Image below) Does it mean, for all two pairs of natural numbers, a and b? How would I represent non pair numbers, i.e. how would I write "For integers k,l, and m such that k>1, l>2, m>k+l" all in one line?

Homework Statement I was in lab and we used a mass hanger and disk and plate attached to pulley to and a motion sensor to measure moment of inertia. Angular acceleration was recorded along with other values such as linear velocity and position and all that. The question is: the hanging mass...

So I'm trying to understand something about the Hulse Taylor Binary. Here they talk about the change in periode that actually changes with the period. So what does Pt mean here? And what is actually being explained? P1year also makes no sense to me. Is that the period after one year? And what...

Hi. I once heard somewhere that atoms of heavy elements like gold get unusual properties such as gold's yellow color due to "relativistic contraction" of the orbitals due to their high "orbital velocity". But what on Earth does orbital velocity mean in quantum mechanics? These are quantum...

Gravitational potential energy between 2 objects is ##-{G\times M\times m\over R}.## My question is, does the value of this equation of this equation mean total gravitational potential energy of both objects ? i.e, say the gravitational potential energy of object with mass ##M## is ##p## and...

It seems like division between two units is a simple intuitive concept to grasp, such as velocity, for every interval of time, a particle travels a certain distance. However, I've always had trouble trying to find an intuitive sense for multiplication between two units, e.g. what exactly does...

The below image shows the end part of a formal proof of the inertia tensor. There's a weird symbol in there that I've never seen before, and google isn't bringing much in the way of explanation. Anybody know what it is? At a guess I'd say it has quite a strong connection to the Kronecker delta...

Obviously ##\mathbb{R^2}## is convex, that is, any points ##a,b\in\mathbb{R^2}## can be connected with a line segment. In addition, ##f## is differentiable as a composition of two differentiable functions. Thus, the conditions of mean value theorem for vector functions are satisfied. By applying...

Homework Statement The concentration of electrons per unit volume is given (atoms/m^3), temperature is also given in Kelvins (100 K). Other values were also given such as valence but I'm pretty sure that they are irrelevant. Homework Equations λ = 1/ pi * d^2 * n λ=kT/4∗π∗√2∗r^2*p The Attempt...

I very often hear scientists talking about how according to modern theories it's completely possible to something manifest out of nothing, and therefore there is nothing illogical of saying that universe came out of nothing. How is this 'nothing' defined and trough what logical process? Very...

I am getting more and more confused when people say or ask if something exists? (Say force, virtual particles, or even spin) Such as, "is wavefunction real?" "Are virtual particles real?" "Are force real?" Are those types of questions usually ill-defined or not well-posed? Or they are just...

Homework Statement What does the symbol [=] mean? Homework Equations The Attempt at a Solution I tried looking this up online but can't find anything. I think it has something to do with dimensional analysis or denoting the units of a quantity. E.g., is it valid to write: t [=] seconds ?

I am trying to read Hugh Everetts thesis about the universal wave function, which is now called the many worlds interpretation of QM. At page 53 ff. he discusses measurements. He talks about a system composed by two state functions, saying that the two subsystems can be considered as measuring...

Homework Statement This is not homework. This is a question given in class with the answers already given. Neither the teacher nor the students have been able to figure out how to obtain the answers though, so my question is how to find them? Here is a picture of the question. The standard...

Homework Statement Find laplace of e-atu(t) where a > 0 Homework Equations Laplace is integration from -inf to +inf f(t)e-stdt u(t) is 1 for t more than equal to 0. The Attempt at a Solution Well i got the answer as X(s) = 1/(s+a). But the book said something like ROC like region of...

Data Data obtained from a survey conducted by a tyre manufacturing company, using a sample of 60 tyres of a certain category, on the distance tyres ran before they became unsuitable for further use. Problem i. What is the modal class ii. Taking the mid value of the modal class as the...

I am faced with a problem in combinatorics while trying to set up a pool. Instead of explaining my real problem, I prefer to give you a simplified example: Say I am given a population of N persons of varying height ##h_i##. The height of each person ##i## in the population is known to me. Now I...

Homework Statement In this problem we will be generating and analyzing lists of normally distributed random numbers. The distribution we are sampling has true mean 0 and standard deviation 1. If we sample this distribution N=5 times, what do we expect the mean to be? How about the standard...

Homework Statement There is almost no helium gas in the earth’s atmosphere - indeed the price of He has increased in recent times due to worries about a limited supply. (Bad news for parties and for all the scientists who use liquid He as a coolant.) we know that the “escape velocity” required...

I've read that this is one of the meaning that define a lepton and I was curious to see what this means. Other resources aren't being very clear.

How do delocalized electrons participated in organic reactions

Why is the term ##(\sin\theta\,\dot{\theta})^2## fourth order in the small ##\theta##, as claimed by the sentence below (5.108)? By small-angle approximation, ##(\sin\theta\,\dot{\theta})^2\approx\theta^2\,\dot{\theta}^2##. For this to be fourth order, it seems like we must have...

Hello all, I have the random variable ##X## with CDF and PDF of ##F_X(x)## and ##f_X(x)##, respectively. Now I have a function in terms of the random variable ##X##, which is ##e^{-X}##, and I want to find the mean of this function. Basically this can be found as...

This is the line: read(A, *) B The variable A is defined earlier in the code. I searched around the internet, and the 'read' syntax requires an input from the keyboard. However, the syntax I saw is read(*, *) var, so the two arguments are both asterisks. What if the first asterisk is defined...

What is "coefficient of restitution between A and B" mean ? Thank you for helping

I am reading European engineering publications, and the circle with a slash shows up about half of the time in front of length measurements. For example, Ø15 x 1.12 mm. What does this mean?

Can you help me figure out what the equation in the attached image means? What I do know is: h(p) is a Monge parameterization height function depending on radius (p), this is a boundary condition for a differential equation, and p0 is the outer boundary, with the inner boundary creating a...

I read in http://www-library.desy.de/preparch/books/vstatmp_engl.pdf page 29 (43 for pdf) that the mean volume is: <V> = \int_{-\infty}^\infty dr V(r) N(r| r_0,s) I have two questions. Q1: why do they take the radius to be from -infinity to +infinity and not from 0 to infinity? Q2: is there an...

[Moderator's note: thread spun off from post in a different thread quoted below.] That seems to me a rather extraordinary claim. Could you demonstrate how for instance cosmological redshift can be explained in a coordinate independent fashion?

Hi there. I want to compare the mean lifetimes of two particles which decay in a way given by two known reaction formulas, such as ##\rho^0 \rightarrow \pi^+ + \pi^-## and ##\Xi^- \rightarrow \Lambda^0 + \pi^-## In this case it's easy: since the first one corresponds to a first interaction...

What made you interested in astrophysics/astronomy? Why is it beautiful? Why is it important?