Mean Definition and 1000 Threads

In an equation, there was an Ept (just those letters) embedded within that equation, does anyone know what it means? LaTeX code doesn't seem to be working either.

I'm filling out a grad application to Berkeley, and one of the forms has the title "Publications and Presentations" and asks I have no publications and I haven't given presentations in the context of a conference or the like, so it seems reasonable to leave this blank. However...

I have an experiment in which I want to extract the distribution function of a process. I expect it to be Gaussian. Each data point measured is an entire distribution, f(x), but I am forced to average over many points such that the result of the experiment is the sum of many measurements of...

What does the "r" in the formula F = - GMm/r^2 mean? Does it mean distance between the two bodies or the radial displacement ? Is the "r" a vector or a scalar?

Hey gang, I was wondering if there is a non-parametric version of the single set TTest? I know that often people refer to the Wilcoxon signed-rank test, but my understanding is that only tells you about the median, correct? Is there an equivalent that deals strictly with the mean? Cheers!

Hi, I am having trouble with this concept... "A mean speed (c) is calculated by multiplying each speed by the fraction of molecules that have that speed, and then adding all the products together. When the speed varies over a continuous range, the sum is replaced by an integral. To employ...

It is an option on the multimeter, I have read a little bit saying it has to do with transistors and it is a "test" for it...

I have a multimeter and for the "ohmeter section" for resistance it goes from a range of ~ 200 Ohms to 2000 kilo-ohms and then says also... Max. Open Circuit Voltage: about 3V Overvoltage protection: 250V AC Thank you in advance

\text{Consider the following decomposition of the time series }{Y}_{t}\text{ where }{Y}_{t}={m}_{t}+{\varepsilon}_{t},\text{ where }{\varepsilon}_{t}\text{ is a sequence of i.i.d }\left(0,{\sigma}^{2}\right)\text{ process. Compute the mean and variance of the process }{\nabla}_{2}{Y}_{t}\text{...

When I see something like "Humans and Bananas share 50% the same DNA with one another!", I have several questions. First of all, a banana has 530 million base pairs whereas a human has approximately 3 billion. Even if we took the first 530 billion base pairs of the human genome, this would only...

Homework Statement Radioactive nuclei are produced in an irradiated sample at the rate of 10 s-1. If the number in the sample builds up to a maximum of 1000, calculate the mean life and the half-life of the radioactive nuclei Can anyone advise on this one not sure how mean life is found...

I know that delta h(Enthalpy) is heat and it is also the total kinetic energy of the system. Temperature is the average kinetic energy of the system from enthalpy. For example, a bathtub may have the same temperature as the ocean, but the total enthalpy will be greater for the ocean...

Homework Statement I have been reading a lot about physics and equation that look like the photo I attached. What do the brackets and the EXP mean? Homework Equations The Attempt at a Solution

What does it mean to boost something along the z axis? To give some acceleration to it, or to spatially translate it? I think it's the 2nd?

Homework Statement Given: 1. a_{1} < b_{1} 2. a_{n} = \sqrt{a_{n-1}b_{n-1}} 3. b_{n} = \frac{a_{n-1} + B_{n-1}}{2} 4. The sequences a_{n} and b_{n} are convergent. Prove: The sequences a_{n} and b_{n} have the same limit. The Attempt at a Solution Assume by contradiction that...

What does p = mv really mean? For example, why is there a physical law based upon the product of mass and velocity? Why does a human made operation, multiplication, give a quantity called momentum? If we define momentum as the product of m and v, why can't we define by some other operation, like...

Definition/Summary The mean value theorem states that if a real-valued function f is continuous and differentiable on an open interval (a,b), then there is a point c in that interval such that f'(c) \ =\ (f(b) - f(a))/(b - a). It also applies if the condition of differentiability is...

I understand that dot product of vectors means projecting one vector on to the other. But I don't understand what is the physical significance of a cross product? I have read that cross product gives the area of the parallelogram which has each of the vectors as its sides...but why do we want to...

Does the existence of the "Axis of Evil" observed by WMAP and Planck mean that there is a special frame of reference in the universe?

Homework Statement Math and verbal SAT scores are each N(500, 10000) 1)If the math and verbal SAT scores were independently distributed, which is not the case, then what would be the distribution of the overall SAT scores? Find its mean and variance. Homework Equations The...

I know some folks may get tired of questions about the finite/infinite scope of the universe. Sorry for that. But as you know, many concepts are hard to wrap one's head around. Let me make my question as clear as possible from the outset: -I am NOT asking whether the universe is infinite or...

Does block universe mean that time and motion are illusions?

Say I have an N X N array of points, I would like a formula to give the mean distance between the points. There are lots of short distances but only two long ones (diagonal). There are plenty of algorithms to do this but I would like to work out a formula if there is one. Can someone point me in...

Hello people of Physics Forums, In my research into transmission lines, I have come across the following function: x = ( a - i * b * tan(t) ) / ( c - i * d * tan(t) ) In the above equation x, a, b, c and d are complex and t is real. If my analysis is correct, varying t from -pi/2 to...

Consider an unbreakable nail. A nail of length 10cm moving at 0.866c. If i stop the nail by hitting its cap, would the tip end countinues to travel?

my question is on part ii, my range ( as shown in the photo), is between 4.52 and 16.28, so my working would be (6+10+4+4)/(6+10+4+4+1) X100% ... the answer given is 72% which is differnt form my answer? which part of my working is wrong ?

I know this question had often been asked on PF but I don't get them. What do mean when we say that space is expanding? I mean that space is no physical entity that can expand. Space is just (apparently) "nothingness". Please solve my confusion.

Hello, Brief context to this question: I'm an economics student and I've recently seen a lecture by phycisist-turned-economist Eric Weinstein, who says that "neoclassical economics is a naturally occurring gauge theory". In response to this, I tried to find out about group theory and gauge...

If we know the mean number density of galaxies in the universe, the redshift z and the Hubble constant. Is it possible to find the mean distance between galaxies at such redshift? The redshift gives a ratio of two distances between the same pair of bodies, at two different time due to the...

Hi All: I am curious about the definition of mean curvature and its apparent lack of invariance under changes of coordinates: AFAIK, mean curvature is defined as the trace of the second fundamental form II(a,b). II(a,b) is a quadratic/bilinear form, and I do not see how its trace is invariant...

Hello look at (3.24). Above it, it states "We make the same switch to polar coordinates (x, φ) in the (x, y) plane, and substitute y ≡ (ax/nπ):" Should (x, φ) be (r, φ)? Is this a typo? Thank you. http://aphyr.com/data/journals/113/comps.pdf

Homework Statement The atmosphere of a star has a mean radiation pressure of 0.33 N m-2and a mean gas pressure of 8300 N m-2. Calculate: a) the mean number density of particles in the stellar atmosphere, and b) the radiation pressure in a stellar atmosphere with twice the effective...

The smallest amount of energy possible is called quantum of energy and is = hf. But are frequencies also quantized? or are they continuous. If frequencies are continuous, then energy can be continuous, no? I am thinking that Planck's constant would mean each frequency has its own quantum...

So I was looking at one of the definitions of first order DE's. But I don't get what this statement means: let a function f(x) be defined on an interval I.

Hi, could you please explain to me what does the following formalisms mean? i'm interested in the body part. Thank you in advance.

Homework Statement GMR_{hollow cylinder}=Re^{-Kμ} where K=\frac{AR^4-R^2r^2+Br^4+r^4ln(R/r)}{(R^2-r^2)^2}, where R is the outer radius and r is the inner radius, and mu is the relative permeability. We are to determine the numerical values of A and B. I am stumped on how to begin attempting...

http://i.imgur.com/DkYMylb.png, probably easier to understand than me trying to type it out. so far I tried exapanding the (y_i - y(x_i))^2 and and then subbing in y_i = ax + b. This gives me part of the answer but I'm not sure if it's legal. I'm generally struggling to find a workable...

Title says it all. I'm reading a lot about the transition metal dichalcogenides and I often see something like 2H-MoS_2 What does that 2H- mean? My best guess is that it has something to do with a hexagonal lattice or stacking or something. Anybody know?

I'm applying for Pusan National University (Busan, South Korea) undergraduate admissions and Physics is my choice of major the question they ask is: Please describe how much have you learned about your intended major? do they want to know my previous experience about learning Physics...

Homework Statement Consider a classical one-dimensional nonlinear oscillator whose energy is given by \epsilon=\frac{p^{2}}{2m}+ax^{4} where x,p, and m have their usual meanings; the paramater, a, is a constant a) If the oscillator is in equilibrium with a heat bath at temperature T...

I was wondering if there is a mathematical difference between the RMS free path and the mean free path of molecules in an ideal gas. For example, When I calculate the mean free path, I use use the average velocity and the scattering rate which is a function of the average velocity. I then...

Homework Statement Let X1, X2,...,Xn be a random sample from the exponential distribution with mean θ and \overline{X} = \sum^{n}_{i = 1}X_i Show that \overline{X} ~ Gamma(n, \frac{n}{θ}) Homework Equations θ = \frac{1}{λ} MGF Exponential Distribution = \frac{λ}{λ - t} MGF Gamma...

When 197 workers aged 18-25 were asked how many hours they worked in the previous week, the mean was 37.7, with a standard deviation of 13.3. Does this suggest that the population mean work week for these age groups differs from 40 hours? Answer by compiling parts.a. Identify the relevant and...

What does "cross section area" mean when dealing with stress/strain? Homework Statement For clarification, here is an example problem: A circular steel wire 2 m long must stretch no more than 0.25 cm when a tensile force of 400 N is applied to each end of the wire. What minimum diameter is...

Homework Statement Silver has a density of 10.5E3 kg/m3 and a resistivity of 1.6E-8 Ω*m at room temperature. On the basis of the classical free electron gas model, and assuming that each silver atom contributes one electron to the electron gas, calculate the average time, Tau, between...

does it mean extract electrons from the out put of laser beem

This isn't a homework question, but while working on some questions in Physics AP C, I've come across several questions involving 0 PD (potential difference). My question is simple; what does 0 PD mean? so far i know that 0 potential difference of any kind is arbitrary, since it represents the...

Hi guys, I am having trouble showing that \mathbb{E}\left[(Y-\mathbb{E}[Y|X])^{2}\right]=0. I understand the proof of why E[Y|X] minimizes the mean square error, but I cannot understand why it is then equal to zero. I tried multiplying out the square to get...

Homework Statement What does it mean? Is this the interval such that 95% of the means from a sample mean distribution (frequency distribution of means of sample size n) are a certain number of standard deviations from the population mean? Homework Equations The Attempt at a Solution

Homework Statement Here is a slide in my notes: I am kind of confused about mean and standard deviation. So in my notes it says X1 to Xn are independent measurements. Then it says each independent measurement has a mean μ. But how is this possible, if they are independent measurements (in...