Variable Definition and 1000 Threads

See photo! Why does the power dissipated increase and then decrease (see graph)? Is it something to do with emf? Also can internal resistance change as the variable resistor increases/decreases or is it always constant? - this isn't one of the questions they ask I'm just wondering

If your doing an experiment to test how the temperature affects a thermistor (increase temp measure v and I...) why do you need a variable resistor in your circuit? Or if you don't NEED one what beneficial use may it pose anyway? Is it something to do with the current? Thanks

Sorry for the simplicity of the question but I encountered a simple math problem whilst autodidacting myself on classical physics. I seen that a surplus of a specific constant variable "b" was extracted from an integral after a bit of manipulation. ∫xdx was turned into b2∫(x/b)d(x/b) Does the...

I'm micro-optimizing my program written in classic C. When I use and [FONT=Courier New]unsigned short int for a boolean value, I need to switch between values of [FONT=Courier New]0 and [FONT=Courier New]1, so what I need to know is whether it's more efficient to use bitshift operators or...

This is an example from a study guide I'm using at the moment in learning C++. //Test whether a number is prime #include <iostream> using namespace std; int main () { int x, y; bool factorFound = false; cout << "Enter a positive integer: "; cin >> y; x = 2; while (x != y &&...

Hi everybody I want to know what's the function of sinusoidal curve but with sharp peaks both positive and negative? In the other word, peaks (positive and negative) be as follows: /\/\/\/\/\/\/\ I mean sawtooth wave, please give an answer that what's the function of the sawtooth wave as...

Hi, I'm trying to identify the free variable and binding occurrence but I'm not sure if they're right in lambda calculus. $x$ $\lambda x.x$ $(\lambda a.z)a$ $\lambda a.za$ $(\lambda n.n)z$ $\lambda z.(\lambda y.(\lambda x.x)y)z$ $(\lambda t.((\lambda t.(\lambda t.t)t)t))t$ Then for free...

Hi! I'm having some trouble with this problem! A small convenience store pays $100 for a constant supply of shampoo bottles. 20 bottles are shipped to the small business. The convenience store then purchases 30 bottles of conditioner for $6 per bottle. What is the fixed and variable cost for...

I have a few questions about entropy and path Scenario I have a closed system of Ideal Gas- Volume is Fixed , Mol Vol is fixed. At room temperature the system is in thermal equilibrium with its surroundings I then cool this system removing Q . To this system I then re-add Q until it is again in...

http://postimg.org/image/pb0eu3ap3/ So I've got this graph, and magnitude, M, depends on the number of points, N,... but it shouldn't. http://postimg.org/image/pb0eu3ap3/ The line of best fit is... M = a*N ^b It's been a while since I studied, but knowing their relationship would it be...

Hello, want to know if it's correct 1. Homework Statement X and Y two random variables iid of common density f and f(x)=x*exp(-x²/2) if x≥0 and f(x)=0 if x≤0 and Z=min(X,Y) Find -The density of Z -The density of Z² - E[Z²] Homework EquationsThe Attempt at a Solution 1.[/B] FZ(u) = P(min(X,Y...

I'm taking an introduction course for simple physics. All problems are solved with simple single variable analysis. My problem is that this is an introduction where you don't need any advanced math to solve the problems, but I can't remember how to solve the last equation. Would you mind helping...

A simple 2 pole alternator (a synchronous generator), is powered by a steam turbine. The amount of steam to the turbine is kept constant with a constant pressure ##p##, flow rate ##\dot{q}##, and power ##P##. If a variable resistor, inductor, and capacitor are connected in series to the...

Homework Statement Force represented by F(t)=20+t+5t^2 [N] acts upon the rim of a disk. How much time has to pass before the disk has angular velocity of 200 revs\sec? R and I are known. Homework Equations \begin{equation*} \tau=I\alpha \end{equation*} \begin{equation*} \tau=R \times F...

When one was reading some review books for engineering mathematics one has come across that kind of notation, below, and where to find books or materials that deals with these kinds of exponents, they look like this>> x^3x+2.

Hey, PF: If I have a function ##f(x)## where ##x## is itself a function of another variable (say time), is the following then true? $$f(x)=f(x(t))=f(t)$$ I ask this because if I have the following system of differential equations $$\frac{dA}{dt}=-Bb$$ $$\frac{dB}{dt}=-Aa$$ where litte ##a##...

Hello all, I have been meditating on this for a while, but can't seem to understand how this simplification came to be. Any help will be greatly appreciated. So, here is what we start with: ##\mathop{\sum_{k=0}^m\sum_{l=0}^n}_{m{\geq}n} x(k,l)## We also know that: l (lower case L) = n-m+k and...

Given the PDF: f(x) = 1/12 , 0 < x <= 3 x/18, 3 < x <= 6 0, otherwise find the expected value, E(x). I know how to find the expected value if there was only one interval, but don't how to do it for two.

Hi. This is not a homework assignment. I am working to get an extrema on a graph that involves a bunch of functions and got stuck on one step: How to get the derivative of: \frac{dy}{dn} = \frac{nc(a+b)}{nc+a} I can't get "n" in a place where I recognize how to get the derivative of it. I...

variable pi formula Diameter (mm) = 0.0000003 : (pi of D - 3.1416 )^2 Pi of D is variable from 3.1416 to 3.1589...

Homework Statement A parallel circuit like that in the figure forms the tuning circuit for an AM radio. If the inductor has a value of 8.6×10-6 H, what must be the maximum and minimum values of the variable capacitor if the radio receives frequencies from 590k Hz to 1670k Hz? a) Maximum C? b)...

Homework Statement Let X be a random variable with the following probability distribution X 0 1 2 3 4 f(x) 1/16 1/4 3/8 1/4 1/16 If another random variable Y = X^2 + 1 is formed, find the mean E[Y]. 2. Relevant equation...

Hi I've been struggling with a fortran 77 code that I need for my astrophysics thesis... Since it's quite old, I'm trying to rewrite some features in order to make it more readable, and I'm trying to make it more rigorous by declaring all variables (I'm declaring "implicit none" everywhere)...

I am reading Manfred Stoll's book: Introduction to Real Analysis. I need help with Stoll's proof of the Inverse Function Theorem (IFT) for real-valued functions of one real variable. Stoll's statement of the IFT for Derivatives and its proof read as follows: In the above proof we read: "...

Homework Statement I am trying to derive the formula for time varying thrust given that I know the initial mass/volume of water in a water rocket. Knowns will include initial pressure, initial volume of water, and nozzle cross sectional area. Homework Equations Bernoullis equation: (p/ρg) +...

Hi. This isn't for any sort of homework. I've run into a deadend where I have a situation like this where I need to solve for "a": a(a+b+c) =d You'd think it would be easy but I can't seem to get "a" by itself. It always end up on both sides of the equation at best which is starting to...

Hello, I am trying to figure out how to clear a variable inside a subroutine from a calling function. The variable in the subroutine acts as a persistent(MATLAB) or static(C), but once in so many calls I want it to be reset to empty as if the subroutine is being called for the first time. I...

I am trying to use a generated random sample in R to estimate the mean and variance for a Poisson random variable. The first one is a Poisson random variable with mean 5. To estimate the above I generate a random sample in R with the following code: P5 <- rpois(100,5) Given the above I want to...

Recently I started seeing integral calculus and right now we are covering the topic of the antiderivative. At first sign it was not very difficult, until we started seeing integral variable substitution. The problem starts right here: Let's suppose that we have a function like this: \int...

Hi, as an engineer i don't have much formal training in theoretical physics so bare with me. As most of you know, we can only understand 4% of our universe with the current models we have. The rest of the 96% is dark matter and dark energy (23% and 73%, respectively). Could these unexplained...

Are many-particles systems theories like the Standard model of particle physics examples of local hidden variable theories?

This is not so much coursework as it is a thought experiment that has been bugging me for a while now. 1. Homework Statement Find the equation for velocity either as a function of distance (x) or time (t). I have an object whose acceleration is given by the rational function a(x) =...

Good day everyone, i have one question. Is it possible to calculate unknown variable on Citizen SR-270x?

I asked my teacher, and I was told that volume is the independent variable, and that pressure is dependent. The textbook I'm using said the same thing. After looking up some graphs of the law, I found that both pressure and volume were used as independent variables. It seems counter-intuitive...

For a generic function ##f##, why is that we use the variable ##x## as the argument of the function? What is the significance of this variable in regards to the object that is the function? Does it denote what the function is able to transform? i.e., ##f(z)## usually denotes a function that...

Hi , When DC is applied to a transformer there is no secondary induction because DC current creates no changing flux in the Core. If I could change the reluctance, or permeability is another word I guess, of the transformer core while still having DC applied to the...

Hey guys, I'm reading my modern physics book over break and I remember hearing that mass changes as you approach the speed of light. But is it really the mass that is changing or just the amount of momentum a certain mass can have. So is mass really varying or is it the energy capacity of mass...

sir, i am looking for fixed DC (110VDC and 220VDC) from my variable AC source (0 to 220V). please support me. rajesh.p 9010770003.

Homework Statement Suppose the conductivity of the material separating two coaxial cylinders, of radius a and b (a < b) and held at a potential difference ##V##, would not be uniform. Specifically, ##\sigma(s) = k/s##, for some constant ##k##. Find the resistance between the cylinders. [Hint...

Hi i want to know how to make a 3D metal box whose length, width, and height i can change. For example, i have a box of 3 m x 3 m x 3 m. i should be able to extend any dimension by a maximum of 1 meter i.e 4 meter (say). I want to use this to store items whose size is unknown, but the limits of...

What I am about to do is write an example of what I call "Physics Math." I am working on a GR problem backward: I have a motion I want to exhibit and am trying to work out the connection coefficients. The problem is that they are in terms of the wrong variable...The equations are expressed in...

So I have X1 and X2 are iid standard normal. Then I have Y=X1^2+ X2^2 and Z=X1/(X1^2+x2^2) I'm supposed to find the distribution of Y and Z and then determine if they are independent. Clearly Y is chi squared with degrees of freedom 2. But I have no idea how to find the distribution of Z...

Homework Statement Solve the following: [/B] y'' = c2 / (x2 + c1*x) * y c1, c2 are constants, x is variableHomework Equations As above The Attempt at a Solution I have used the method of Frobenius and regular power series and obtained an infinite series on top of an infinite series, which is...

Is there a simple formula to find the amount of money in an account given a situation like this... You deposit x into the account Each year you get interest Year one the interest is 1% Year two the interest is 2% Year three the interest if 3% and so on Is it possible to get a simple general...

Homework Statement Let X denote a continuous random variable with probability density function f(x) = kx3/15 for 1≤X≤2. Determine the value of the constant k. Homework Equations I'm not sure if this is right but I think ∫kx3/15 dx=1 with the parameters being between 2 and 1, The Attempt at a...

Homework Statement If X is uniformly distributed over (0,1), find the PDF of Y = |X| and Z = e^X Focusing on the |X| one Homework Equations Derivative of CDF is the PDF The Attempt at a Solution So I start by writing down the CDF of X, Fx(x): 0 for x <0 x for 0 ≤ x ≤ 1 1 for x ≥ 1 And I...

Homework Statement Here's the problem with the solution provided: Homework Equations Fundamental Theorem of Calculus (FToC) The Attempt at a Solution So I understand everything up to where I need to take the derivative of the integral(s). Couple of things I know is that the derivative of...

Homework Statement Evaluate: I(y)= \int^{\frac{\pi}{2}}_{0} \frac{1}{y+cos(x)} \ dx if y > 1 Homework EquationsThe Attempt at a Solution I've never seen an integral like this before. I can see it has the form: \int^{a}_{b} f(x,y) dx I clearly can't treat it as one half of an exact...

Although the speed of light is constant in GR, within coordinate spacetime the speed of light varies. For example, light travels more slowly near a black hole than in remote space. The same is theoretically true of the speed of gravity. But is there any supporting empirical evidence?

Is this possible? It seems like it should be but, it's difficult to find an explicit relationship between a general function of one variable x (let's say we are only interested in functions that decay to zero as they go to plus or minus infinity) it seems like summing a bunch of gaussians of...