Joint Definition and 327 Threads

Homework Statement Homework Equations The Attempt at a Solution The problem is the integral is non-elementary, so now what? Part (b) follows trivially from part (a). But is there some kind of shortcut I have to take, because no matter what substitution I do, the integral...

In quantum mechanics, there doesn't seem to be a joint distribution of position and momentum. But in Bohmian mechanics there is. But Bohmian mechanics is quantum mechanics, so what is the error in my reasoning?

I understand that defining the path of a joint in a mechanism comes under the category of 'kinematic analysis'. I do not understand why engineers do this,when all they need to know is the path of the piston,piston velocity and piston acceleration(kinematic analysis). Take for example this 90...

Hi, I was just wondering if anyone know of an operator, which has some realistic analogue, that would perform the following action: A|N,0> = A|0,N> Where the ket's represent two joint fock states (i.e. two joint cavities) and A is the opeator I desire. I thought that the beam...

I am trying to select a bolt for a butt joint connection. When you guys do bolt selection, are there certain equations you use to determine if the bolt will rigidly hold the 2 parts together in the joint?

Problem statement: Two 3/4-in.-diameter nylon rods are spliced together by gluing a 2-in. section of plastic pipe over the rod ends, as shown in the figure. If a tensile force of P = 500 lb is applied to the spliced nylon rod, what is the average shear stress in the glue going between the pipe...

Dear all, Greetings! I was given a problem from Reichl's Statistical Physics book. Thank you very much for taking time to read my post. Homework Statement The stochastic variables X and Y are independent and Gaussian distributed with first moment <x> = <y> = 0 and standard deviation...

Homework Statement The stochastic variables X and Y are independent and Gaussian distributed with first moment <x> = <y> = 0 and standard deviation σx = σy = 1. Find the characteristic function for the random variable Z = X2+Y2, and compute the moments <z>, <z2> and <z3>. Find the first 3...

Homework Statement Determine whether each joint is in tension or compression (correct answers on the image) Homework Equations sum of force = 0 The Attempt at a Solution On Joint I, I don't understand why IH is in tension. The pin is exerting a horizontal force and...

Hello everyone! The problem: $X,Y,Z$ are random variables that are dependent and uniformly-distributed in $[0,1]$, and let $\alpha$ be a given number in $[0,1]$. I am asked to compute the following: $\text{Pr}(X+Y+Z>\alpha \;\;\; \& \;\;\; X+Y\leq \alpha)$ What I have so far...

Please refer to the attached image. How am I supposed to integrate this, it's impossible to find anything!

(please refer to attached image) The question appears to be simple enough, but i have two queries A) does E[X1 X2] mean the same as E[X1 | X2] B) If not/so, how exactly do I go about computing this. I've seen a few formulas in my lectures notes for computing conditional expectations for...

Homework Statement Roll a 6-sided die 5 times. Event X is when a 1,2,3 shows up. Event Y is when 4,5 show up. Show the joint PMF. Homework Equations The Attempt at a Solution So... here is where I am at... X~Bin(5,0.5) & Y~Bin(5,1/3) P(X=x)=(5 C x)(.5^5) &...

The below gives all the information I was given. I'm pretty sure my answer is right, but a part of me isn't, and that's why I'm asking here. Homework Statement Let (X,Y) have the joint pdf: f_{XY}(x,y)=e^{-y}, 0 < x < y < \infty Find E(XY). Homework Equations...

Hi all,I just started to learn mechanics so please forgive me if i ask something elementary.I have an example from Egor P Popov's Engineering mechanics of solids.(Please refer attachment and sorry about quality of drawing). This is a problem of a pin joint system subjected to vertical load...

Homework Statement Given joint pdf: f(x,y) = (2/(x2(x-1)))(y-(2x-1)/(x-1)) x>1, y>1 find marginal pdf fx(x) Homework Equations fx(x) = ∫f(x,y)dy, 0, ∞ The Attempt at a Solution fx(x) = ∫(2/(x2(x-1)))(y-(2x-1)/(x-1)) dy, 1, ∞ = [-2y(x/(1-x))/x3],1,∞ = undefined. stuck here

Hello, I'm about to be a Sophomore in Fall this year and current major is Software Engineering. My school offers a joint major in Computer Science and Engineering (as well as separate CS and Comp. Engr.). I'm looking into it as I don't want to be pigeon-holed as just a programmer but I'm not...

Suppose u1 and U2 are a sample from Unif(0,1). X= 1{u1<=1/2} , Y=1{u2<=1/3} Get the joint dist of X+Y and X-Y Is it jointly discrete or jointly abs cont? How do info about finding the joint dist??

If "A" were a joint of the body, what is the compressive/tensive force at the joint? I already figured out the torque about A to be 6.840 Nm, but I'm not quite sure how to go about figuring out compressive/tensive forces. Normally, there would be a force associated in the area or angles...

Hi, Homework Statement I am having difficulties understand parts of the solution to the following problem in Statistics: Let X and Y be two random, continuous variables, where X is distributed U(0,1) and Y|X=x is distributed U(x,x+1). I am asked to find the marginal density of Y. Homework...

A joint pdf is given as pxy(x,y)=(1/4)^2 exp[-1/2 (|x| + |y|)] for x and y between minus and plus infinity. Find the joint pdf W=XY and Z=Y/X. f(w,z)=∫∫f(x,y)=∫∫(1/4)^2*e^(-(|x|+|y|)/2)dxdy -∞<x,y<∞ Someone told me I can not use Jacobian because of the absolute value. Is that true? So...

Dear Friends, Hi,I am senior mechanical engineering student and I'm working on my final project which is designing an AGV vehicle.I designed a space chassis for it and have a problem with analyzing the joint I designed using Solidworks.I do not know how can I should define support...

A joint pdf is given as pxy(x,y)=(1/4)^2 exp[-1/2 (|x| + |y|)] for x and y between minus and plus infinity. Find the joint pdf W=XY and Z=Y/X. f(w,z)=∫∫f(x,y)=∫∫(1/4)^2*e^(-(|x|+|y|)/2)dxdy -∞<x,y<∞ Someone told me I can not use Jacobian because of the absolute value. Is that true? So far this...

A joint pdf is given as pxy(x,y)=(1/4)^2 exp[-1/2 (|x| + |y|)] for x and y between minus and plus infinity. Find the joint pdf W=XY and Z=Y/X. f(w,z)=∫∫f(x,y)=∫∫(1/4)^2*e^(-(|x|+|y|)/2)dxdy -∞<x,y<∞ Someone told me I can not use Jacobian because of the absolute value. Is that true...

Homework Statement f(x,y) = x2 + xy3 for 0 < x < 1, 0 < y < 2 and 0 otherwise. Calculate P(X+Y < 1) Homework Equations The Attempt at a Solution P(X+Y < 1) = P(X < 1-Y) which means y is now bounded by 0:1 instead of 0:2 and x is bounded by 0:y. So we get ∫[0-1]∫[0-y] x2 +...

Homework Statement We sample a population 50 times with replacement, with all individual sampled equally likely. We survey the gender and quality of life. The counts are: Male: 13 high quality, 11 low | female: 18 high, 8 low. Let P_M, P_F, P_H, P_L to denote these population proportions for...

I'm practicing the past year papers to prepare for my coming finals. Please make necessary corrections if you feel something wrong with it, thanks! Also, I'm supposed to do this in less than half an hour, so any suggestions on how to shorten this answer is really much appreciated! Homework...

Hello everyone, I am a high school senior. I got accepted to UC Berkeley, and will be attending the school this coming fall. I want to pursue nuclear engineering in college. Since UC Berkeley offers joint major programs, I would like to pursue a joint major (nuclear + another engineering...

Homework Statement Let X and Y have the joint probability density function f(x,y)=k(1-y), if 0<x<y<1 and 0 elsewhere. a)Find the value of k that makes this pdf valid. b) Find P(X<3/4,Y>1/2) c) Find the marginal density function of X and Y d) Find the expected value and variance of X and...

Homework Statement Suppose X and Y have the joint probability density function: f(x,y) = x+4y, 0<y<x<1 f(x,y) = 0 otherwise Find P(X>4Y) Homework Equations The Attempt at a Solution I'm not sure how to do this. I've already found marginal pdf's for x and y.. although I...

Homework Statement The joint PDF (probability density function) ##p_{X,Y}(x,y)## of two continuous random variables by: $$ p_{X,Y}= Axy e^{-(x^2)}e^{\frac{-y^2}{2}}u(x)u(y)$$ a) find A b) Find ##p_X (x), \ p_{y}, \ p_{X|Y}(x|y), and \ p_{Y|X}(y|x)## Homework Equations The first...

Homework Statement Let X and Y be random variables of the continuous type having the join p.d.f.: f(x,y) = 8xy, 0<=x<=y<=1 Find the marginal pdf's of X. Write your answer in terms of x. Find the marginal pdf's of X. Write your answer in terms of x. Homework Equations The...

Two rods of different materials with coefficients of linear expansion α1 and α2 respectively; Young's moduli Y1 & Y2 respectively; of initial lengths l1 and l2 respectively are joined at one end. the free ends are fixed to two vertical walls as shown in the fig. Temperature of the surrounding...

I have this question: and I'm a little confused. To calculate joint distributions in the earlier questions i was using:P_{(\xi1,\xi2)}(x1,x2)=P_{(\xi1)}(x1)P_{(\xi2)}(x2)But that would mean that if:P_{(\xi1,\xi2)}(2,0)=0\ either\ P_{(\xi1)}(2)=0\ or\ P_{(\xi2)}(0)=0which can't be true in...

Homework Statement The joint probability density function of X and Y is given by f(x, y) = c( x3 + xy/4 )  0 < x < 1 0 < y < 2 (a) For what value of c is this a joint density function? (b) Using this value of c, compute the density function of Y . (c) Using this value of c, nd PfX...

As I've been looking at universities this year, a lot of them offer a joint bachelors and masters in math for undergrads, and I'm unsure if this is a good idea. I'm afraid that I won't get a thorough, well-rounded education if I rush through things, but on the other hand it could be helpful get...

Given that the joint probability Pr(w,x,y,z) over four variables factorizes as Pr(w,x,y,z) = Pr(w) Pr(z|y) Pr(y|x,w)Pr(x) show that x is independent of w by showing that Pr(x,w) = Pr(x)Pr(w). Attempt: if we simply assume Pr(x,w) = Pr(x)Pr(w), then: \begin{align} Pr(w,x,y,z) &= Pr(w)...

I would like to impedance match a few joints in a circuit and would appreciate some thoughts about this, since I would like the match to be as perfect as possible. The problem is complicated by the fact that the available equipment only consists of trimpot(s). The joints are mostly cables to...

X and Y are independent, exponentially distributed random variables - with possibly different parameters Determine the density func. of Z = X / Y How to attack ?

Homework Statement Hi, so I am having trouble understanding the steps to get to certain densities. For example, suppose i have data y1,...,yJ ~ Binomial (nj,θj) We also have that θj ~ Beta (α,β) Now our joint posterior is: p(β,α,θ|y) ~ p(α,β) ∏ (\Gamma(α+β) / \Gamma(α)\Gamma(β))...

Homework Statement Hi all, I'm looking at the joint pdf F(x,y) = (8+xy^3)/64) for -1<x<1 and -2<y<2 (A plot of it is here: https://www.wolframalpha.com/input/?i=%288%2Bxy%5E3%29%2F64+x+from+-1+to+1%2C+y+from+-2+to+2 ...sorry about the ugly url) and trying to find the marginal PDFs for X and...

Hi all, I'm looking at the joint pdf F(x,y) = (8+xy^3)/64) for -1<x<1 and -2<y<2 (A plot of it is here: https://www.wolframalpha.com/input/?i=%288%2Bxy%5E3%29%2F64+x+from+-1+to+1%2C+y+from+-2+to+2 ...sorry about the ugly url) and trying to find the marginal PDFs for X and Y. I know I want to...

i have to design an actuation system which will change the angle with which the power is transmitted through a motor,the range of angle is about,--35 to +35,w.r.t to the vertical,what should i use,a u joint or a velocity joint?there is a predefined load on the shaft(bending + torsional),what...

You know how sometimes, you take a long time to write a question, and then you submit, but it takes you to a login screen and then you lose everything you wrote? Anyhow...I would just like to verify some work here. The problems states that there are 3 mutually independent random variables...

Homework Statement f_xy(x,y)= 24xy for o<x<1 and 0<y<1-x let z=[1-x]/y and w=y determine joint density of wz and E(z) Homework Equations The Attempt at a Solution E[z] = Integral [0,1] integral [0,1-x] 24xy*(1-x)/y dydx = 2 The joint distribution doing a...

Homework Statement Suppose that f_{X,Y}(x,y)=\lambda^2e^{-\lambda(x+y)},0\le x,0\le y find E[X+Y]Homework Equations The Attempt at a Solution I just want to double check I didn't make a mistake: E[X+Y]=E[X]+E[Y]=\int_0^{\infty} x{\lambda} e^{-\lambda x} dx + \int_0^{\infty} y{\lambda}...

I have to calculate the number of M6 Button head screws required to hold a door panel of 40 kg when 700N (calculate at the center line of the mounting holes) of force is applied laterally. I want to consider only lateral case when the force is applied perpendicular to the door panel. Any idea...

I'm curious if anyone has any experience working for two advisers, particularly in two different fields. In my case, I'd focus on synthesizing materials in a chem lab (that focuses on synthesis) and then working in a EE/physics lab that would focus on characterizing said material, in particular...

Homework Statement We are given a belief network such that the overall joint probability after accounting for conditional independence is: P(a,b,c,d,e) = P(a)P(c|a,b)P(d|b)P(e|d,b) The values provided are: P(a = false) = .02 P(b = false) = .95 P(c= false|a=true, b=true) = .97 P(c=...

Find the joint CDF of 2 R.V with joint PDF of triangular support Homework Statement Given the 2 random variables X and Y, their joint density given by: f(x,y) = c(x + y^2) for all (x,y) in the triangle 0<y<x<1 and f(x,y) = 0 elsewhere. Compute the joint distribution function F(X,Y)...