Distribution Definition and 1000 Threads

My end goal is to extrapolate observed intelligences in the animal kingdom to determine whether or not it is statistically likely that a simulation argument is probable (though this could easily be used for the Fermi Paradox as well). Defining terms: "intelligence." Obviously all animals would...

I have a 2x4 on it's edge that spans 10 feet in my ceiling. I want to hang a swing that can hold 250 pounds near the center of this span. What would I need to do in this situation in order to get minimal or no deflection?

In kinetic theory, the number of molecules hitting a unit area of a surface per unit time with speeds between v and v + dv and angles between \theta and \theta + d \theta is found to be a function of sin(theta) and cos(theta). There will often be a practice problem asking to show that the...

Homework Statement A car is on a ramp of angle theta with the horizontal with the front of the car pointing up the ramp. Its weight distribution is uneven so that more of its weight is towards the rear of the car therefore the center of mass is closer to the rear of the car. The car is very...

Homework Statement In a company, out of a sample of 20 bulbs, the mean number of defective bulbs are 2. Out of 1000 such samples, how many samples would have atleast 3 defective bulbs? Homework Equations Mean = n * p where n is number of bulbs and p is probability of a bulb being defective...

Homework Statement Can someone explain why f(x) = 1/(b-a) for a<x<b ? Homework EquationsThe Attempt at a Solution shouldn't it be 0? since its a continuous random variable and so that interval from a to b has an infinite number of possible values?

This thread is prompted by a closed thread which left it’s OP’s original question unanswered. ->https://www.physicsforums.com/threads/average-wavelength-for-blackbody-radiation.423536/ The original question asked: is the ratio, of (a) the wavelength corresponding to the average energy in the...

So let's say I do some measurements and obtain a set of measured values. The measurement is characterized by random errors so by making enough measurements, they approach a normal distribution. In other words, my set of measured values can be approximated by a normal distribution characterized...

Hello everyone, I am working on a project in astrophysics in which I need to include now some type of particle distribution (as a function of the radius). I was wondering if there is some accepted function that would describe the number of particles per radius in astrophysics. Saturn's rings...

Homework Statement For the circled part , i don't understand why it's 4 and 6 . I know that it's about distribute the moment according to the ratio that we have determined earlier . Homework EquationsThe Attempt at a Solution For 4 , shouldn't it be 240*0.4 = 96 ? For 6 , shouldn't it be...

Homework Statement Initially there is a spherical charge distribution of with a radius ##R_0## and uniform charge density ##ρ_0##. Suppose the distribution expands spherically symmetrically such that its radius at time t is ##R_0 + V t##, where V is the velocity. Assuming the density remain...

When computing the probability distribution of bosons, why is A = 1 for photons? Does this not imply that photons will have an increasingly high probability of being present as E approaches 0? What is the significance of such a situation?

Hey! :o I am looking at the following: The average tallest men live in Netherlands and Montenegro mit $1.83$m=$183$cm. The average shortest men live in Indonesia mit $1.58$m=$158$cm. The standard deviation of the height in Netherlands/Montenegro is $9.7$cm and in Indonesia it is $7.8$cm...

Diffusion of gases seems to follow normal distribution. I imagine deviations from the mean would depend on temperature, mean free path and speed of gas molecules. Any other? Cheers, Glenn

What does the distribution curve of IQ in the world population look like? If the average IQ for all countries is 90 (Richard Lynn and Tatu Vanhanen “IQ and the Wealth of Nations”), with an average IQ for sub-Saharan Africans of 70, I suppose that the distribution curve is higher on the downside...

If the normalized probability density of the normal distribution is ## p(x) = \frac {1}{\sqrt{2\pi}\sigma} e^{-\frac{(x-\mu)^2}{2\sigma^2}} ##, then if ##\sigma = 0.0001## and in the special case ## x = \mu##, wouldn't the probability density at this point, ##p(\mu)##, exceed 1 since it is equal...

Homework Statement Hi, I have the probabilty density: ##p_{n}=(1-p)^{n}p , n=0,1,2... ## and I am asked to find the characteristic function: ##p(k)= <e^{ikn}> ## and then use this to determine the mean and variance of the distribution. Homework Equations [/B] I have the general expression...

I have calculated characteristic function of normal distribution f_{X}(k)=e^{(ika-\frac{\sigma ^{2}k^{2}}{2})} and now I would like to find the moments, so I know that you could expand characteristic function by Taylor series f_{X}(k)=exp(1+\frac{1}{1!}(ika -...

Hello, guys. I am trying to solve for characteristic function of normal distribution and I've got to the point where some manipulation has been made with the term in integrands exponent. And a new term of t2σ2/2 has appeared. Could you be so kind and explain that to me, please...

Hello Everyone Hope you will be fine I am trying to estimate assembly wise power distribution of pwr core. Can anyone let me know if F7 tally correspond directly to power distribution or else i need some additional calculations?

In a digital communication channel, assume that the number of bits received in error can be modeled by a binomial random variable, and assumed that a bit is received in error is 1×〖10〗^(−5) . if 16 million bits are transmitted, What is the probability that more than 150 errors occur? Find the...

Assuming that the number of marks scored by a candidate is normally distributed, find the mean and the standard deviation, if the number of first class students(60% or more marks) is 25, the number of failed students(less than 30%marks) is 90 and the total number of candidates appearing for the...

I'm trying to figure out why my back hurts when I sleep and I can't figure out the physics behind it. So I sleep on an air mattress. The mattress fits firmly into the frame, which puts a constraint on the mattress to where it cannot expand on it's sides. Think of the mattress as being in a box...

Homework Statement On average, 2 students per hour come into the class. What is the probability that the time between two consecutive arrivals is in the interval <10 minutes; 50 minutes>. Homework Equations p(k)=P(Y=k)=((lambda*t)k*(e-lambda*t)/k! The Attempt at a Solution I've tried using...

Hey all, So the question in Jackson 1.4 is that I have 3 spheres that all have a total charge Q on them, but each sphere has different material properties. For instance, I have a conducting sphere, a sphere with a uniform charge distribution, and one with a charge distribution that has a...

Hi everyone. I've been considering switching out of using a Windows laptop in favour of Linux. What I'm curious of is do any of you here on PF use the Linux OS. If so, which distribution do you use (Ubuntu, Fedora, etc.)? What has been your experience using Linux? Appreciate any insights any of...

Homework Statement find the average energy of a system with n energy states (0, 1E, 2E, 3E...nE) Homework Equations P(E) = e-BE/Z - where B=1/KbT and Z= ∑e(-BE)n <E>=∑(nE* (e-BE)n) /Z The Attempt at a Solution i feel like I've gone down the correct path - that is finding result of the sums. Z...

Homework Statement An initial particle distribution n(r, t) is distributed along an infinite line along the z-axis in a coordinate system. The particle distribution is let go and spreads out from this line. a) How likely is it to find a particle on a circle with distance r from the z-axis at...

Homework Statement Hi everybody! I'm very stuck trying to solve this problem, hopefully some of you can give me a clue about in which direction I should go: Determine the multipole expansion in two dimensions of the potential of a localized charge distribution ##\lambda(\vec{x})## until the...

Homework Statement A barbershop has two barbers: an experienced owner and an apprentice. The owner cuts hair at the rate of 4 customers/hour, while the apprentice can only do 2 customers/hour. The owner and the apprentice work simultaneously, however any new customer will always go first to the...

The question asks: A physical device can be in three states: A,B,C. The device operates as follows (all time units are in hours): The device spends an exponentially distributed amount of time in stateAA (with mean of 12minutes) and then with probability 0.6 goes to state B, and with...

So the problem asks: A computer server runs smoothly for Exp(0.2) days and then takes Exp(0.5)days to fix. The server is running fine on Monday morning, t=0. Find the probability that the server was fixed at least once (i.e. at least one complete repair was done) in the next 7 days and the...

This is my first time using this site so please excuse me if I missed any guidelines. 1. Homework Statement A plastic rod having a uniformly distributed charge Q=-25.6pC has been bent into a circular arc of radius R=3.71cm and central angle ∅=120°. With V=0 at infinity, what is the electric...

Maxwellian velocity distribution is obtained by $$g(v_x)\propto e^{-mv_x^2/2k_B T}$$ and when extended to 3 dimensions the distribution becomes: $$\propto e^{-mv_x^2/2k_B T}e^{-mv_y^2/2k_B T}e^{-mv_z^2/2k_B T} = e^{-mv^2/2k_B T}$$ Now looking at the speed distribution we take a spherical shell...

Homework Statement I am told that the gravitational force of a mass m located inside an isotropic distribution of spherical radius R and total mass M is given by Fg = -GmM(r)/r^2 where r is the distance between m and the center of distribution and M (r) is the mass contained below the distance...

Hello PF, I am trying to analyze a a beam, connected to another beam at one side at multiple locations (bad quality drawing below). The top side of the beam extends further and sit on another beam, while the shorter lower side is directly connected to another beam. They are all bolted...

Homework Statement The average lifetime of muons at rest is τμ0 = 2.2 μs. A laboratory measurement on the decay in flight of muons in a beam emerging from a particle accelerator yields an average lifetime of τμ = 6.6 μs, as measured in the lab frame Σ. (g) [3 points] Given a large ensemble of...

I am doing a project for a course and it asks me to draw annotated drawings of the distribution network including generators, transmission systems, distribution system and low voltage loads which in general is all fine. However, I have come across a question that asks me to draw an annotated...

Homework Statement Gas particles of a particular gas have a speed distribution function of fv = Cv/(v2 +vo2)2 a. Find the value of C b. Calculate the most probable speed c. What fractions of the particles are moving faster than the most probable speed Homework EquationsThe Attempt at a...

Hi guys, I have a question about computing conditional probabilities of a Poisson distribution. Say we have a Poisson distribution P(X = x) = e^(−λ)(λx)/(x!) where X is some event. My question is how would we compute P(X > x1 | X > x2), or more specifically P(X> x1 ∩ X > x2) with x1 > x2? I...

Is the distribution the same as Boltzmann distribution? Have anyone made a mathematic equation for the KE of free electrons on a piece of metal?

Hello, I have a question about Boltzmann Distribution. I wonder why partial N of Nj is 1 and partial U of Nj=Ej. because N is constant, partial N of Nj has to be 0 and Partial Nj of U has to be 0 as well. They are constants so, to make sense of the equation, alpha and beta have to be 0 but...

please am new here and i need a help, i can use poisson distribution to get a probability but how can i use it to get several outcome? like over and under ,1x2? thanks

Hey guys, I am building a small water ramp that will extend from a dock and into the water with a buoy at the end. I could probably just use trial and error, but thought it would be fun to make some rough calculations to help my design. This picture (http://imgur.com/a/bHYfG) shows the...

Is this a ground breaking observation or does it agree with other observations? atures and the Wing-Ford band, presented in a recent paper. arXiv:1610.03854 [pdf, ps, other] The observed spatial distribution of matter on scales ranging from 100kpc to 1Gpc is inconsistent with the standard...

Hello everybody, - In quantum mechanics, the state ## | \psi \rangle ## of a system that is in thermodynamic equilibrium can be expressed as a linear combination of its stationary states ## | \phi _n \rangle ## : $$ | \psi \rangle = \sum_n c_n | \phi _n \rangle $$ It permit us to express the...

I'm looking for the inverse functions of the Maxwell-Boltzmann distribution and Planck's Law. Planck's Law in terms of the wavelength. Any of you know of any literature on this topic?

Homework Statement Consider helium as ideal gas with a Maxwell distribution of speeds. (a) Investigate the maximal value Fmax at the peak of the Maxwell distribution F(v): Calculate this value for He at T = 300 K and at 600 K, and for N2 at 300 K b) For He at 300 K, obtain speeds v1...

Hello. Given a range of time in which an event can occur an indefinite number of times, we say a random variable X folows a poisson distribution when it follows this statements: X is the number of times an event occurs in an interval and X can take values 0, 1, 2, … The occurrence of one event...

Homework Statement The Lorentz Distribution is given by p(x) = \frac{1}{pi}\frac{ϒ}{(x-a)^2+ϒ^2} for -∞≤x≤∞. a) Sketch the distribution for a=0, ϒ=1, and compare the form to the Gaussian Distribution. b) Calculate the first moment of the distribution assuming again that a =0 and ϒ =1. c)...