Value Definition and 1000 Threads

  1. E

    MHB Find the value of the iterated integral

    Give your answer in exact form. Format ±X/Y ± is if the value is positive or negative (Duh) X is the numerator (e.g. 7) Y is the denominator (e.g. 11) the question:
  2. T

    Find the probability of energy value after a given measurment

    Homework Statement I am having a issue conceptualising the problem as I believe the answer is 0. Part c) Homework EquationsThe Attempt at a Solution My answer is 0 and it for the following reason. A the being say time t=0 the system is in some arbitary state, then when I got to measure the...
  3. J

    Expectation Value of a Stochastic Quantity

    Homework Statement I'm working on a process similar to geometric brownian motion (a process with multiplicative noise), and I need to calculate the following expectation/mean; \langle y \rangle=\langle e^{\int_{0}^{x}\xi(t)dt}\rangle Where \xi(t) is delta-correlated so that...
  4. Jonforall

    Must we always use absolute value for lens magnification?

    My brother's physics teacher says that magnification and height of image are always positive. Is she right?
  5. L

    Find the smallest value for the polynomial

    The graph below shows a portion of the curve defined by the quartic polynomial P(x) = x^4 + ax^3 + bx^2 + cx + d. Which of the following is the smallest?https://imgur.com/a/1VuGSiA(A) P(-1) (B) The product of the zeros of P (C) The product of the non-real zeros of P (D) The sum of the...
  6. D

    Is the Extra Term in the Expectation Value Calculation Zero?

    Homework Statement Show that, for a general one-dimensional free-particle wave packet $$\psi (x,t) = (2 \pi h)^{-1/2} \int_{-\infty}^{\infty} exp [i (p_x x - p_x^2 t / 2 m)/h] \phi (p_x) dp_x$$ the expectation value <x> of the position coordinate satisfies the equation $$<x> = <x>_{t=t_0}...
  7. M

    MHB Which is the mean value of the sample?

    Hey! :o We have the following hypotheses: $$H_0: \mu\geq 60 \ \ \ , \ \ \ H_1:\mu<60$$ A test is executed with a sample of size $25$ and an estimated standard deviation $S'=8$. From the test we get a p-value of 5%. I want to determine the value of the mean of the sample $\overline{X}$. The...
  8. Pattarasak

    I Measurement of the mean value of the number of photons?

    Hi everyone, I do experiment in field of quantum optics and I want to calculate the mean of the number of photons (MNP). In the most of papers, MNP can be calculated by using average power which is measured by power meter. But my power meter is defective. For now, I have only the avalanche...
  9. Saracen Rue

    Determine what value of a allows for largest probability

    Homework Statement There are two possible solutions for 'a' for which ##f(x)=|x^x-x^a|## is a probability density function. Determine the value for a which produces a PDF with the largest probability of random variable 'x' falling within two standard deviations either side of the mean.Homework...
  10. Y

    MHB Solve Logarithms Problems: Find Profit & Interest Rate

    Hello all, I have a few small questions regarding logarithms, which I would like to ask your help with. 1) A car loses 50% of it's value every 4 years. How many years does it take for the car to lose 1/3 of it's value ? (I think you need log with basis of 2 here, but not sure) 2) A company...
  11. kvothe18

    I Mean value of the nuclear tensor operator

    Does anyone know how can you prove that the mean value of the tensor operator S12 in all directions r is zero? S12 : http://prntscr.com/j3gn40 where s1, s2 are the spin operators of two nucleons.
  12. F

    The value of potential difference between two points

    Homework Statement Homework Equations ##ΔV=Ed## The Attempt at a Solution ##V_A=E l## ##V_b=0## , because point B is perpendicular to the electric field ##ΔV = V_a + V_b## = El Is my answer correct ?
  13. M

    MHB Greatest probability - Expected value

    Hey! :o The geometric distribution with parameter $p\in (0,1)$ has the probability function \begin{equation*}f_X(x)=p(1-p)^{x-1}, \ \ x=1, 2, 3, \ldots\end{equation*} I have shown that $f_X$ for each value of $p\in (0,1)$ is strictly monotone decreasing, as follows...
  14. Jakub

    I Small Reduced Chi Squared interpretation

    Hello everyone, I would be happy if someone explained the small reduced chi squared value to me. I have fitted a set of measured data with an exponential function, which I need for some sw calculations. The fit seams great, the origin sw also provides the reduced chi squared, but it is very...
  15. S

    Expectation Value and Probabilities of Spin Operator Sy

    Homework Statement (a) If a particle is in the spin state ## χ = 1/5 \begin{pmatrix} i \\ 3 \\ \end{pmatrix} ## , calculate the expectation value <Sy>(b) If you measured the observable Sy on the particle in spin state given in (a), what values might you get and what is the probability of...
  16. J

    MHB Expected Value of Gambling Strategy - Martin's Winnings

    This question comes from the "Introduction to Probability" book (Blitzstein & Hwang). Martin has just heard about a gambling strategy: bet 1 dollar that a fair coin will land heads. If it does, stop. If it lands tails, then double the bet for the next toss, now betting 2 dollars on heads. If it...
  17. Jeviah

    How to get the third value (A), using partial fractions

    Homework Statement y(w)= 3/(iw-1)^2(-4+iw) Homework Equations N/A The Attempt at a Solution 3/(iw-1)^2(-4+iw) = A/iw-1 + B/(iw-1)^2 + C/-4+iw for B iw = 1 B=3/-4+1 = -1 for C iw = 4 C= 3/(4-1)^2 = 1/3 I know the answer for A should be -1/3 however I am unsure how to obtain this as if the...
  18. Sandro Romualdez

    Vectors: Proving the value of a•(b x c)

    Homework Statement Given that vector a = (1, 2, -5), b = (-12, 41, 75) and c = a + 2b, explain why (without doing any calculations whatsoever) the value of a•(b x c) = 0 Homework Equations No specific equations, as the question asks for the value without making any calculations. This problem...
  19. R

    Finding the maximum value of current through the inductor

    Homework Statement Homework EquationsThe Attempt at a Solution [/B] I got the first 2 parts, but I'm having trouble with the last one. For the time the switch S1 is closed, I derived ##q(t) = CE(1 - \cos(\frac{t}{\sqrt{LC}}))##, by writing the loop equation ##\frac{E}{L} - \frac{1}{LC}q =...
  20. renec112

    QM: expectation value and variance of harmonic oscillator

    Homework Statement A particle is moving in a one-dimensional harmonic oscillator, described by the Hamilton operator: H = \hbar \omega (a_+ a_- + \frac{1}{2}) at t = 0 we have \Psi(x,0) = \frac{1}{\sqrt{2}}(\psi_0(x)+i\psi_1(x)) Find the expectation value and variance of harmonic oscillator...
  21. hilily

    I Why “If Lz has a well-defined value, then Lx and Ly do not”?

    On Griffiths's book page 166 first paragraph he said " It's not merely that you don't know all three components of L; there simply aren't three components—a particle just cannot have a determinate angular momentum vector, any more than it can simultaneously have a determinate position and...
  22. S

    I Linear mapping of a binary vector based on its decimal value

    Given an ##N## dimensional binary vector ##\mathbf{v}## whose conversion to decimal is equal to ##j##, is there a way to linearly map the vector ##\mathbf{v}## to an ##{2^N}## dimensional binary vector ##\mathbf{e}## whose ##(j+1)##-th element is equal to ##1## (assuming the index starts...
  23. mishima

    B Absolute Value Inequality, |x|>|x-1|....where's my mistake?

    Rule: Suppose a>0, then |x|>a if and only if x>a OR x<-a So |x|>|x-1| becomes: x>x-1 which is false (edit: or more accurately doesn't give the whole picture, it implies true for all x) OR x<-x+1 2x<1 x<1/2 which is false
  24. CricK0es

    How Should Error Be Calculated When Determining Angles from Voltage Maxima?

    Homework Statement I have taken 5 sets of readings of voltage against angle for an experiment to determine specific rotation. (I'm using the maxima to determine the phase shift) So, having averaged these values and determined the maximum, I can then trace back to the angle at which this...
  25. M

    A Value at Risk, Conditional Value at Risk, expected shortfall

    I am working on Value at Risk and expected shortfall/conditional Value at Risk.The formula I have is this: What I do not understand is numerator of the second part. If for example I want to look at an expected shortfall when p=0.01 (ignoring the average and the standard deviation). what value...
  26. M

    MHB How can I determine the biggest trig value without a calculator?

    How do I determine which trig value is bigger or smaller without using a calculator? Sample: Which is bigger: cos 2 or sin 2?
  27. SuchBants

    Uncertainty larger than the plotted value

    Homework Statement I'm determining g by the extension of a spring. I used a PASCO motion sensor to record the displacement of the spring towards the sensor since it is more accurate than myself using a ruler. The uncertainty in the distance on the sensor is 0.8%. I get the uncertainty in...
  28. L

    B Find the missing energy value given a set of data (Hypothetical question)

    Hypothetical question: Let's say there's a granite cube with a volume of 60 cubic centimeters. A cannon ball is shot at it, reducing it to rubble, and the kinetic energy of the ball was 10,000 joules. We use the same ball with the same kinetic energy output on a stronger unknown substance with...
  29. opus

    Finding the exact value of cos(arcsin())

    Homework Statement Find the exact value of ##y=cos\left(arcsin \frac {5} {11} \right)## Homework EquationsThe Attempt at a Solution I'm stuck at square one. I know that I must evaluate arcsin first, which will give me an angle θ. From that angle, I can take the cosine of it and that much makes...
  30. C

    (Numerical) Boundary Value Problem for Schrodinger's Equation

    Homework Statement Suppose we have the standard rectangular potential barrier in 1D, with $$ V = \left\{ \! \begin{aligned} 0 & \,\text{ if } x<0, x>d\\ V_0 & \,\text{ if } x>0,x<d\\ \end{aligned} \right. $$ The standard approach to solve for tunneling through the barrier is to match the...
  31. Rectifier

    What Is the Value of the Infinite Sum \(3 \sum_{k=1}^\infty \frac{1}{2k^2-k}\)?

    The problem I'd like to calculate the value of this sum: $$3 \sum^\infty_{k=1}\frac{1}{2k^2-k}$$The attempt ## 3 \sum^\infty_{k=1}\frac{1}{2k^2-k} = [k=t/2] = 3 \sum^\infty_{t=2}\frac{1}{2 \left( \frac{t}{2} \right)^2-\frac{t}{2}} = 3 \sum^\infty_{t=2}\frac{1}{ \frac{t^2}{2} - \frac{t}{2}} = 3...
  32. M

    MHB Why can't real numbers satisfy this absolute value equation?

    Explain, in your own words, why there are no real numbers that satisfy the absolute value equation | x^2 + 4x | = - 12. Can we say there is no real number solution here? If so, is the answer then imaginary taught in some advanced math class?
  33. yecko

    Initial value problem question

    Homework Statement Homework Equations ## y(t)\mu(t) - y(t_0) \mu(t_0) = \int_{t_0}^t \mu(s) g(s) ds## ## y(t) = \frac{1}{\mu(t)} \left[y_0 \mu(t_0) + \int_{t_0}^t \mu(s)g(s) ds\right]## The Attempt at a Solution (7 lines)I have done the first part, which seems correct, yet I am stuck with...
  34. sparkie

    Calculating Serial Baud Rate from Measured Value

    Homework Statement The problem is to calculate the baud rate of a serial transmission by measuring the length of time required to send the ASCII character 'Z' over a serial port. The serial port settings are 9600 baud with a start and stop bit, no parity and a data size of 8 bits. Homework...
  35. M

    I Comparing two absolute value equations

    Hello, How does one go about algebraically checking if |x+|y+z|| and ||x+y|+z| are equal?
  36. T

    Finding the min value using the derivative

    Homework Statement Hi I'm having a trouble with finding min value of given function: f(x) = sqrt((1+x)/(1-x)) using derivative.First derivative has no solutions and it is < 0 for {-1 < x < 1} when f(x) is given for {-1 < x <= 1}. For x = - 1 there is a vertical asymptote and f(x) goes to +...
  37. Monoxdifly

    MHB [ASK] Induction Determine the value of n if 1 + 3 + 6 + .... + n(n - 1)/2 = 364

    Determine the value of n if 1 + 3 + 6 + ... + \frac{1}{2}n(n - 1) = 364 What I did: I know that 1, 3, and 6 are the result of arithmetic series with the starting value 1 and the difference 2, thus that sum can be written as S1 + S2 + S3 + ... + Sn = 364. However, by assuming that Sn =...
  38. Robin04

    Find the Value of k: Ball's Momentum and Height

    Homework Statement We release a ball from a height h and it bounces for a time t. What is the value of k (the quotient of the ball's momentum before and after collision with the ground)? Homework EquationsThe Attempt at a Solution I'm kind of lost here. :/ [/B]
  39. D

    Finding the Average Value of a Function

    https://imgur.com/a/Maq1N 1. Homework Statement Attached above is the problem statement. Essentially, they've given two different volumes involving some unknown function f(x) and ask that you find its average value over the given closed interval. Homework Equations Relevant equations include...
  40. Richie Smash

    Find the value of beta in degrees

    Homework Statement In triangle ABC AC= 9cm, BC=5cm and angle ACB = β in degrees. Given that cos2β=0.84, determine (i) the exact value of sin2B (ii) the value of β if 90°<β<180° (iii) the length of AB Homework Equations sin2θ+cos2θ=1 The Attempt at a Solution Using that equation In relevant...
  41. aquaelmo

    Find the cdf given a pdf with absolute value

    Homework Statement Consider a continuous random variable X with the probability density function fX(x) = |x|/5 , – 1 ≤ x ≤ 3, zero elsewhere. I need to find the cumulative distribution function of X, FX (x). 2. Homework Equations The equation to find the cdf. The Attempt at a Solution FX(x)...
  42. D

    Expectation Value of Q in orthonormal basis set Psi

    Homework Statement Suppose that { |ψ1>, |ψ2>,...,|ψn>} is an orthonormal basis set and all of the basis vectors are eigenvectors of the operator Q with Q|ψj> = qj|ψj> for all j = 1...n. A particle is in the state |Φ>. Show that for this particle the expectation value of <Q> is ∑j=1nqj |<Φ|...
  43. Richie Smash

    Value of x for which f(x) is undefined

    Homework Statement Given f(x)=\frac{3x-2}{x+1} Calculate the value of x, for which f(x) is undefined. Homework EquationsThe Attempt at a Solution Hi, I've never come across this before and I'm not finding anything on the internet, I would post my attempt but the problem is I don't know where...
  44. Richie Smash

    Find the value of alpha and beta (matrix equation)

    Homework Statement Hello, I have three matrices A = [3 -4 2 1] B = [α β] C= [α 5] The question now states AB = C Find the values of (alpha) and (beta). Homework EquationsThe Attempt at a Solution I found the inverse of A, then I multiplied each side of the equation AB=C by the inverse...
  45. D

    Engineering Calculating the effective value and frequency of AC Circuit

    Homework Statement For AC Circuit shown in the picture, ##C=60nF##, ##L=100uH##, ##X_3=-100Ω##, ##Z_2=50Ω## and ##Φ_2=\frac {\pi}{6}##. When the switch is closed the ammeter shows a current ##I_1=0.6A## and the voltmeter shows ##U_l=60V##. The measuring instruments mentioned are ideal...
  46. J

    Lag Compensator Find Value of 'a'

    Homework Statement [/B]Homework Equations I used voltage divider rule. The Attempt at a Solution I get value of a = 3 Book answer is 1.5. Is book wrong or am I wrong?
  47. mertcan

    I Derivative of infinitesimal value

    Hi, it may be interesting question but what is the d (dy)/dx (y is function of x)? I think it is nearly zero but if it is 0 then how can we prove it?
  48. Y

    MHB Determining Value of a in Matrix A with $\lambda$ = 0

    Hello all, Given the following matrix, \[A=\begin{pmatrix} 2 & 6\\ 1 & a \end{pmatrix}\] and given that \[\lambda =0\] is an eigenvalue of A, I am trying to determine that value of a. What I did, is to create the characteristic polynomial \[(\lambda -2)*(\lambda -a)+6=0\] and given...
  49. S

    I What does a zero-value of the Born-condition mean?

    Hi, I was wondering what is the physical meaning of these integrals: \begin{equation} \int_{-\infty}^{\infty} \psi \psi^* dx = 0 \end{equation}\begin{equation} \int_{-\infty}^{\infty} \psi x \psi^* dx = 0 \end{equation} \begin{equation} \int_{-\infty}^{\infty} \psi p \psi^* dx = NA...
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