Standard Definition and 1000 Threads

  1. gfd43tg

    Standard form of linear program

    Homework Statement To preface, I believe this question is equally applicable to either the math or engineering homework forum, but I am having more trouble with the math part than the actual programming. I can't do any programming (with the understanding that linear programming doesn't...
  2. P

    Exploring the Mystery Of Lattice Energy Under Standard Conditions

    My A level Chemistry textbook defines Lattice Energy as "the enthalpy change when 1 mole of an ionic compound is formed from its gaseous ions under standard conditions"; a definition which I can't fully grasp because of the "standard conditions" part. How can gaseous ions exist under standard...
  3. M

    What is meant by standard error for linear and quaratic coefficients ?

    Dear Fellows, If we fit our data to a quadratic equation then What is meant by standard error for linear and quaratic coefficients ? I know that standard error is the standard deviation from the Sampling data. But for individual coefficients what is its interpretation ? Best Wishes Masood
  4. B

    Calibrating Equipment to Standard: Can A Volt Ever Be Accurate?

    I've worked in calibration for a few years and I know that my equipment has to be calibrated by a standard that is a certain amount more accurate than the piece of equipment I'm calibrating, but where exactly does it end where the most accurate piece of equipment is calibrated by the absolute...
  5. tlnarasimham

    In the standard model gravitron is a particle but Higgs boson is not?

    In the standard model gravitron is a particle but Higgs boson is not. The Higgs field causes particles to acquire mass. Mass generates a gravitation field. Is gravitron is in any way related to Higgs boson? Is the Higgs field any way related to gravitation field?
  6. K

    Range of one standard deviation from mean

    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 ?
  7. D

    Standard entropy of a liquid at melting temperature

    I am presented a review of data which gives: vapour pressures of a liquid have been measured and fit to the following equation: Log10 (mmHg) = -3571/T + 8.999 The melting point has been determined to be 392.7 K. A Cp value given for the liquid is 250 J/mol K and the ΔSvap is 117 J/mol K...
  8. L

    How do D-Brane arrangements affect particle masses and the standard model?

    Hi. I've been reading that if one places a Dp brane in a 10d space then it's possible to have a string with [11] Chan-Paton index i.e. a string that starts and ends on the same Dp brane. Since the separation of the brane with itself is 0, this string corresponds to a massless particle. Why is...
  9. O

    Standard deviation in exponential distribution

    What is the significance of the standard deviation (equal to the mean) in an exponential distribution? For example, as compared to the standard deviation in the normal distribution, which conforms to the '68-95-99.7' rule? thanks
  10. D

    Standard Entropy of a liquid at melting point with no S(298.15) given

    Homework Statement Vapour pressures of a liquid have been measured and fit to the following equation: Log10 P (mmHg) = -3571/T + 8.999 The melting point has been determined to be 392.7 K. A Cp value given for the liquid is 250 J/mol K and the ΔSvap is 117.20 J/mol K Homework Equations...
  11. D

    How Do You Calculate Standard Entropy at the Melting Point?

    Homework Statement vapour pressures of a liquid have been measured and fit to the following equation: Log10 (mmHg) = -3571/T + 6.124 The melting point has been determined to be 392.7 K. A Cp value given for the liquid is 250 J/mol K and theΔSvap is 117 J/mol K Homework Equations...
  12. D

    Standard Entropy for Liquid at Melting Point

    Homework Statement The vapour pressures of a liquid have been measured and fit to the following equation: Log10 (mmHg) = -3571/T + 6.124 The melting point has been determined to be 392.7 K. Calculate the standard entropy of the liquid at the melting point. Homework Equations...
  13. tom.stoer

    Standard model gauge anomaly cancellation

    There are quite subtle gauge anomaly cancellations in the standard model. Does anybody know a good summary about the algebraic constraints for number of fermions per generation, value of electroweak charges, etc.?
  14. gfd43tg

    Standard Gibbs energy change definition

    Hello I am working on deriving the expression relating the equilibrium constant K to the change in Gibbs energy. This part seems to be followed okay, but here I am not following why the change in Gibbs energy of reaction is defined this way. I can see why K is defined in a way because...
  15. M

    Standard Sci-Fi Battles Using Fluid as the Medium?

    Hello! I'm working on creating a sci-fi setting for a tactical space combat video game and short story series, and I had a few questions I couldn't find much info on after googling. I'll be playing a little bit loosely with the laws of physics for the sake of gameplay and storytelling, but I...
  16. J

    Exploring the Limitations of Standard Diesel Engines

    this is thing I'm thinking about for few years. why standard passenger car diesel engines are so limited in engine capacities range? if we take petrol engines, there are anything from 1.0 liter to 3.0l Inline 4 cylinders, 2.0-4.0l 6 cylinders (or even bigger in USA), 4-7l V8 etc. but take...
  17. T

    Confused about what the standard order is?

    In my previous two math classes I'd get the answer wrong if I put the number first then the variable as my answer. Now in this class this way of doing it is wrong. I'm seriously confused now. For instance the last two classes said that it was standard practice to write an answer like: 3x+4. This...
  18. N

    Standard Deviation of Kinetic Motion

    If thermodynamic temperature can be interpreted as the average kinetic energy in a system, is there a quantity defined as the standard deviation? For example, let's say you poured some hot water into a cup of cold water. The instant you poured it the standard deviation of the system would be...
  19. U

    Standard change in entropy and change in entropy

    In the Gibbs free energy equation, does the standard change in entropy equal q(sys)/T(system)? Or in math terms: T(surr) * q(sys)/T(sys) = T(surr) * dS(standard) Thus dS(standard) = q(sys)/T(sys) (surr) = surroundings (sys) = systems (standard) = at standard conditions
  20. M

    Voltage and standard reduction potential?

    We're doing electrochemistry this week and this concept confuses greatly. I know that voltage is the work per unit charge. And electrons move from high potential(is this voltage as well?) to low potential- what is meant by this by the way? How is this related to standard reduction potential? If...
  21. T

    Confused about mean and standard deviation for samples

    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...
  22. I

    Power distribution standard and safety measures help please

    good day everyone, I wonder if anyone can direct me please on the international standard number or name that explain the safety and standard procedures in better distribution of power in breakers and panels from transformers. in short, as I learned in my school and as best practice that...
  23. L

    Dispersion or standard deviation?

    In some textbooks ##\Delta \hat{x}## is called dispersion of coordinate ##\Delta \hat{x}=(\langle \hat{x^2} \rangle-\langle \hat{x} \rangle ^2)^{\frac{1}{2}}##. For me that is standard deviation. What do you think?
  24. R

    MHB Transform Random Var CDF to Standard Normal: F(x)=1-exp(-sqrt x)

    How to transform a random variable CDF to a standard normal Given F(x) = 1- exp (-sqrt x), for x greater that 0 Thanks.
  25. nomadreid

    Missing step in standard proof of |P(N)|=|R|

    There are several ways to show the one-to-one correspondence between P(N) (= the power set of the natural numbers) and the set of the reals (or, equivalently, the set of reals in the interval [0,1).) Continued fractions, and all that. However, one argument is the following (sorry, this argument...
  26. R

    What Is the Standard Deviation of the Volume?

    Hello A manufacturer produces blocks of metal of length 100 standard deviation 2, width 200 standard deviation 1 depth 150 standard deviation 3 The mean volume will be 100x200x150 but what will its sd function be? (The figures I've given are just for clarity) Thanks in advance...
  27. M

    Linear function standard basis.

    Does anyone know what L is? I'm trying to see if I could find videos on it on YouTube. On the first question this is what I think- [a;b] is a vector by the way: 1) [2;1]c1+[7;4]c2=[1;0] [2;1]c1+[7;4]c2=[0;1] I could have also combined those two by having the linear combination equal to a size...
  28. D

    Standard Additions plotting in excel

    Homework Statement I have a set of values from a laboratory work (standard Additions practical), which I am required to plot. I am finding difficulties in plotting the values in excel because the horizontal axis must have some negative integers. Homework Equations The Attempt at a...
  29. S

    Finding the Standard Deviation from Probability

    Homework Statement For a certain random variable X, P(X≤500)=.5 and P(X>650)=.0227, find σ. Homework Equations μ=expected value=mean Variance=∫(X-μ)2fx(X)dx evaluated from -∞ to ∞ σ=√Variance The Attempt at a Solution I'm not sure what the relationships between the...
  30. S

    Converting Normal Distribution to Standard Normal

    Homework Statement Let X1,X2,X3 be a random sample from a normal distribution with mean μ≠0 and variance σ2=1/24. What are the values of a and b, respectively, in order for L=aX1+4X2+bX3 to have standard normal distribution?Homework Equations σ=1/√24 Converting normal distribution to...
  31. F

    Converting Density to Standard Density

    I have an application where I need to find the density of a substance at standard conditions (101.325kPA, 15°C) from the density at recorded conditions (varies). The first application is for natural gas at approximately 11Barg (160 psi, 1100kPA), 80°C (176°F). The second application is for...
  32. M

    What is a Standard State or Reference State of an element?

    What is a Standard State or Reference State of an element? Can someone please give me a simple explanation of what a standard state or reference state is? I don't quite understand the way wiki describes it which is - The standard state, also known as reference state, of an element is...
  33. S

    Spontaneous symmetry breaking in the standard model

    In the standard model, the Lagrangian contains scalar and spinor and vector fields. But when we consider spontaneous symmetry breaking, we only account for the terms contain only scalar fields, " the scalar potential", in the Lagrangian. And if the scalar fields have vacuum expectation value...
  34. Spinnor

    Adjust parameters of Standard Model so only photons, e-, e+ remain?

    Could you have a hypothetical universe with only photons, electrons, and positrons by adjusting the parameters of the Standard Model to eliminate all the "other" stuff? If so is String Theory flexible enough to model a hypothetical universe with only photons, electrons, positrons, and...
  35. gfd43tg

    Which Methanol State to Use for Heat of Reaction Calculations?

    Hello, I am confused about the following scenario. Suppose I have the reaction CO (g) + 2H2 (g) → CH3OH (g) and I am asked to solve for the heat of reaction at 800 C. My query is the following: when finding the heat of reaction at standard state, which heat of formation I should use...
  36. Chronos

    SN1a under fire as standard candles

    This paper, http://arxiv.org/abs/1402.2717, discusses an alternative model for SN1a progenitors and offers observational predictions to test it based on SN2014J. If the model is validated it would have far reaching consequences for cosmology.
  37. S

    Standard deviation is wrong whatever I do?

    After filling out the table, I used it to finally calculate the standard deviation as 0.105. Just to make sure, I ran it through Microsoft Excel and got 0.942809042. I put two together and figured I'm doing something wrong after the xw column because Excel agrees that the mean is also 1.7...
  38. M

    Calculus III; standard form of & angle to eliminate the cross produc

    Hi; I've been trying to solve the problem myself but i really don't what could be wrong; The problem says : Make the change of variables x=ucos−vsin y=usin+vcos where the angle 0<(phi)<2 is chosen in order to eliminate the cross product term in x^2+xy+y^2=6 Then find the standard form of...
  39. V

    Database of theories beyond the standard model?

    I am a programmer and physics fan. A speaker (Lawrence Krauss?) at https://origins.asu.edu/events/great-debate-parallel-realities-probing-fundamental-physics (not on youtube yet) said physics theories beyond the standard model are an under-determined problem. There are 7,000 theories that fit...
  40. END

    Standard Deviation Conceptual [intro. Stats]

    Hello, PF! [My question pertains to a non-rigorous, undergraduate introductory Probability and Statistics course. I'm no math major, so please correct me if I've mishandled any terms or concepts as I try to express myself. I'm always eager to learn!] * * * In a discussion of the...
  41. C

    Places to study Physics Beyond The Standard Model.

    I am a MSc student and I am looking for a place to do my PhD in Physics Beyond the Standard Model (Theoretical side). Any suggestions for a place to apply?. I know that there are the traditional elite places like MIT, Standford, Berkeley and so on but I am looking for other suggestions given...
  42. P

    What is the Standard State of Carbon?

    Homework Statement Graphite can be change into diamond according to the following equation: Cgraphite ==> Cdiamond Consider the following reaction equations: Cgraphite + O2 (g) ==> CO2 (g) ΔH = -393.5 kJ/mol Cdiamond + O2 (g) ==> CO2 (g) ΔH = -393.4 kJ/mol Which form of...
  43. N

    What is standard early inflationary cosmology?

    I am wondering whether discussions of inflationary cosmology in these forums generally includes or explicitly excludes prior Plank era and GUT era dynamics. I never gave it any thought until reading the following. The Wikipedia article provides a perspective I just don't remember from other...
  44. N

    Degree of freedom and formula for standard variation

    For a set with n points of data, why is the "degree of freedom" of the standard variance n-1? Hell, what does "degree of freedom" actually mean? Heck, my book "proves" this by saying that since ##\sum_1^n (x_i - \bar{x}) = 0## (obviously), then ##\sum_1^n (x_i - \bar{x})^2## must have n-1...
  45. M

    Heading to Standard Angle: Is 330 Degrees 30 Degrees?

    Hi all, Would a heading of 330 degrees be equivalent to a standard angle measurement of 30 degrees? I'm used to calculating by subtracting the heading from 90, but the angle is too large for this problem. I know it seems to be a ridiculously simple question compared to others on this forum...
  46. skate_nerd

    MHB Is the Statement True or False?

    Studying for my proofs final right now...there's a problem on the study guide: True or False. Assume standard properties of real numbers. Support your answers. (a) For all \(x\) in the real numbers, there exists a \(y\) in the real numbers such that \(x+y>0\). The answer: True. Given an \(x\)...
  47. S

    Using a Platinum Electrode & HCl in a Standard Hydrogen Electrode

    In Standard Hydrogen Electrode why only Platinum electrode should be used and why should it be dipped in HCl?why can't we use any other metal dipped in any other acid other than HCl?
  48. Z

    MHB Standard deviation for proportions

    Hi,,,can u please explain me how to calculate standard deviation and standard error for a binomial distribution when you have several samples? For exapmple: I don't know the population size. I take a sample of 10 and check for a particular characteristic. Let's say number of successes for this...
  49. B

    Multiplying matrix units and standard basis vectors

    Hello all, I don't have a question on homework specifically, but I need clarification on something I'm reading in the textbook. I will be starting an abstract algebra class in the spring and it's been quite a few years since I've had linear algebra, so I'll be reviewing that material before the...
  50. Q

    Symmetry Groups of the Standard Model: SU(3) x SU(2) x U(1)

    I have a question regarding symmetry groups. I've often heard that the Standard Model is a SU(3) x SU(2) x U(1) theory. From what I understand these groups contain the symmetries under which the Lagrangian function is invariant. If so, what does every one of the 3 groups above contain (what...
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