Test Definition and 1000 Threads

I work in a large electrical machine shop. We have a test that no one can explain to me. We energise a dc field frame (in this case 6 pole) with ac and record the current draw, then reverse the polarity of connection, energise and compare values. If a pole is reversed polarity then a difference...

High school student here. I have just over a month until my AP Calculus exam. I love math and I'm confident that I understand all the concepts necessary to ace the exam. Here's the catch: Whenever I work with a ticking clock, I either don't finish every question in time or make a bunch of silly...

Would you consider yourself creative? http://www.testmycreativity.com

I would just like to draw some attention to this recent preprint https://arxiv.org/abs/1703.04426 It reports on a test of time dilation based on a fiber network of optical clocks. No deviation from relativity predictions found.

Hello Experts, I have created this thread especially for clearing some of the important concepts of Antenna and Designing Issues. I have a question for all of you, related to Dipole Antenna. I have designed a Folded Dipole Antenna resonating at center Frequency of 145.800MHz. This antenna is...

Pages 41-44 of this document discuss the various continental nuclear test sites that were considered before the selection of Nevada. While North Carolina seems like an unusual choice at first, it would be in close proximity to Savannah River Site in South Carolina. North Carolina also...

Hi everyone! I'm starting to work with a mini X-ray tube provided by Amptek. I want to use it to calculate the efficiency of a detector I'm going to use latter, so knowing the total flux the tube emmits and measuring the flux the detector receives, that should be enough (both data normalized to...

Hello! I am in 9th grade and I am really interested in physics. I got this book from my uncle on my birthday but it says there is calc in it: https://www.amazon.com/dp/0321973615/?tag=pfamazon01-20 I can't give it back because its disrespectful in my culture. Can I still learn from this, or...

It's a huge problem for me, and only after turning it in, do I realize that I made a few mistakes; then I constantly worry about how that will affect my test score. Has anyone ever experienced this before? How would I cope with it? I don't think I would be able to deal with the stress of...

Could someone please explain to me what is the definition of a pulse current discharge, and what do we mean by pulse current discharge test ?

Hi, I have measured secretion of a hormone and I am normalizing it to the total cellular content of the hormone. I have used Grubb's test for determining outliers (GraphPads online calculator) and there are no outliers in the values for amount of secreted hormone, nor for hormone content...

Imagine I have a complicated second-order differential equation that I strongly suspect can be derived from a Hamiltonian (with additional momentum dependence beyond p2/2m, so the momentum is not simply mv, but I don't know what it is). Are there any ways to test whether or not the given...

I want to study chi square test of homogeneity from any authentic source- book / website especially problems where samples are compared for more than one attribute. What are some relevant sources? Relevant background: I was studying examples from random online sources before I saw this book...

Test for symmetry about the x-axis, y-axis and the origin. |x + y| = 2 About y-axis: |-x + y| = 2 Not symmetric about y-axis. About x-axis: |x + -y| = 2 I say not symmetric about the x-axis. About the origin: |-x + -y| = 2 Not symmetric about the origin. Correct? If not, why?

Test for symmetry about the x-axis, y-axis and the origin. x + |y| = 2 About y-axis: -x + |y| = 2 Not symmetric about y-axis. About x-axis: x + |-y| = 2 x + y = 2 I say not symmetric about the x-axis. About the origin: -x + |-y| = 2 Not symmetric about the origin. Correct? If not, why?

Hi guys. I'm relatively new to the Physics Forums, so forgive me if this question has been asked a bunch already. (I'm sure it has). I'm currently a junior in UCLA and majoring in Physics. I want to go to grad school (not sure which yet) so I'll obviously need to take both the general GRE and...

I'm having someone make something for me. I wanted to know the best way I could test a whole bunch of different materials with different friction, texture and tactility. Where can I get a load of samples to test? I may have to reach out to different sources and purchase the different materials.

Homework Statement Use a comparison test to determine whether this series converges: \sum_{x=1}^{\infty }\sin ^2(\frac{1}{x}) Homework EquationsThe Attempt at a Solution At small values of x: \sin x\approx x a_{x}=\sin \frac{1}{x} b_{x}=\frac{1}{x} \lim...

Homework Statement \sum_{x=2}^{\infty } \frac{1}{(lnx)^9} Homework EquationsThe Attempt at a Solution x \geqslant 2 0 \leqslant lnx < x 0 < \frac{1}{x} < \frac{1}{lnx} From this we know that 1 / lnx diverges and I wanted to use this fact to show that 1 / [(lnx) ^ 9] diverges but at k...

Homework Statement Hello, I've stumbled upon an interesting analysis of GLM's in R (http://www.magesblog.com/2015/08/generalised-linear-models-in-r.html). However it's only a graphical analysis so I wanted to make sure the models are fitting by using an actual statistics test. The test...

Homework Statement A thin semicircular rod is broken into two halves. The top half has a total charge +Q uniformly distributed along it, and the bottom half has a total charge -Q uniformly distributed along it. A negative test charge is placed at points A, B, and C. *Image attached* Consider...

TheAdmin submitted a new PF Insights post Test Your NASA Knowledge Continue reading the Original PF Insights Post.

The problem I am trying to show that the following integral is convergent $$ \int^{\infty}_{2} \frac{1}{\sqrt{x^3-1}} \ dx $$The attempt ## x^3 - 1 \approx x^3 ## for ##x \rightarrow \infty##. Since ## x^3 -1 < x^3 ## there is this relation: ##\frac{1}{\sqrt{x^3-1}} > \frac{1}{\sqrt{x^3}}##...

Homework Statement I would like to understand how the limit was changed in the ratio test from step 1 to step 2 in the image that I've posted. I thought that the denominator would look like (2/n+2)(2/n+1) in step 2 since it looks like we are just turning the n's into reciprocals. Any help here...

Hi.. I want to know how can we specify the data(electrical) passing through cable that we are designing in CST design studio to test the effect of EMI on the data passing?

Lab manual is confusing me, and I'm not sure if its actually wrong, or the wording is bad, or if this is because I'm not understanding something. It says: "Before a broth can be tested for nitrate reductase activity it must be examined for evidence of denitrification. This is simply a visual...

I am trying to better understand likelihood ratio test and have found a few helpful resources that explicitly solve problems, but was just curious if you have any more to recommend. Links that perhaps work out full problems and also nicely explain the theory. Similar links you have found...

$\tiny{206.f3a.}$ $\textsf{Use the divergence Test to detemine whether the series is divergent}$ \begin{align} \displaystyle &\sum_{k=1}^{\infty}\frac{\arctan(2k)}{1+4k^2}\\ \textit{take limit}\\ =&\lim_{{k}\to{\infty}}\frac{\arctan(2k)}{1+4k^2}\\ \\ =&\frac{\arctan(\infty)}{\infty}...

$\tiny{206.8.8.17}$ $\textsf{Evaluate the following integral, or stat that it diverges.}\\$ \begin{align*} \displaystyle && I_{17}& =\int_{0}^{\infty}36x^8 e^{-x^9}\, dx& &(1)&\\ && &=36\int_{0}^{\infty}\frac{x^8}{e^{x^9}}\, dx & &(2)&\\ \end{align*} $\textit{first what be the recommended...

Homework Statement Hi there I have problem I hope some can help me solve. My H0, there is no connection between people who received the new and old medication? And them getting well or not well. I suppose to test the following data using Chi-square test in SPSS. \pmatrix{\\\textrm{"""} &...

You got to love this! A top experimental team was assembled to test the "freedom of choice" loophole (if you can call it that). Usually, when random settings are needed in a Bell test, a computer generated value is obtained (pseudo random), or similar. This is relatively "local", and subject...

Hey! :o To check the convergence or divergence of series there are the following tests: Trivial test If a series $\sum a_k$ converges, then the sequence $a_k$ is a zero-sequence. With this test we can just prove the divergence, but not in general the convergence of a series. \ Ratiom...

$$\sum_{k=1}^{\infty}\left(\frac{k}{k+1}\right)^{2k}$$ $\textsf{how do you use absolute converge test on this?}$ ☕

Homework Statement Use variation of parameters to solve ##\frac{d^2y}{dx^2} + 4y = sec(2x)## Homework Equations Really just curious about comments, see picture. The Attempt at a Solution I'm having a hard time deciphering the comments I got back on an exam. For the first comment, is there a...

hi all, i just want you to tell me if my ideas are correct or not : As far as i can see the R^2 test is usually used in OLS (ordinary least squares) method where many conditions for data is showed (something like linearity in coefficients, expectation values for perturbations must be zero, and...

$\tiny{206.10.5.84}$ \begin{align*} \displaystyle S_{84}&=\sum_{k=1}^{\infty} \frac{(4x)^k}{5k}\\ \end{align*} $\textsf{ ratio test}$ $$\frac{a_{n+1}}{a_n} =\frac{ \frac{(4x)^{k+1}}{5(k+1)}}{ \frac{(4x)^k}{5k}} =\frac{4xk}{k+1} $$ $\textsf{W|A says this converges at $4|x|<1 $ so how??}$

Hello, I'm checking the similarity of two methods for my research (a gold-standard method and another one which I need to check if it’s eficiente compared to the gold-standard) with student t test. I have the following datas (N=3): method 1 (gold-standard): 120, 347, 116; method 2: 2603...

Good day guys :cool: I need your help. I am going to run the open field test for social behavior, I need to put two rats in open field arena and then to measure what time they will spend close to each other or far from each other, also to see the distance they cover. Essentially, I need to...

In pascal triangle, if all the elements of a row(except 1 in both end) are divisible by the row number, then the row number is a prime. Or if the coefficient of binomial expansion (except 1's) are divisible by the power, then the power is a prime. It is inefficient to check all the coefficient...

As I understand it most, if not all, experiments carried out to test Bells theorem test the local hidden variables assumption that photons have definite polarisations. What I would like to know is whether experiments on properties other than polarisation have been carried out. If not are there...

$\tiny{206.b.46}$ \begin{align*} \displaystyle S_{46}&=\sum_{k=1}^{\infty} \frac{2^k}{e^{k}-1 }\approx3.32569\\ % e^7 &=1+7+\frac{7^2}{2!} %+\frac{7^3}{3!}+\frac{7^4}{4!}+\cdots \\ %e^7 &=1+7+\frac{49}{2}+\frac{343}{6}+\frac{2401}{24}+\cdots \end{align*} $\textsf{root test}$...

I have a hypergeometric distribution with: N=total population of red and green balls, I now this K=total number of red balls, I don't know this n=sample size (number of investigated balls), I can choose this k=number of investigated balls that are red, I don't know this Red balls are a problem...

Homework Statement Determine whether the system is linear Homework Equations Superposition The Attempt at a Solution I am comfortable solving the case where the bounds are from negative infinity to t. I have provided an example of that solution I found online. I attempt to solve that...

How can i test the concentration of h2o2?

I am a high school student replicating the Faraday Effect. I plan to insert a clear liquid, such as distilled water, into a container that will be located inside of solenoid. I plan on using a test tube, however, I have doubts on whether or not the curved bottom of a test tube will alter the...

i wanted to ask you that i am having financial problem for preparing for exams for getting admission into international universities. are there online test series for physics,chemistry,maths in free

hi there, i am going to study for GRE Physics test . i want anyone to guide me for an easy book for that . and i want to know which of this 2 books is more related to the gre test - physics for scientists and engineers by Serway & Jewette - fundamental of physics by Halliday & Resnick

If $\{x_n\}_{n \ge 1}$ is real sequence and $\limsup\limits_{n \to \infty} \frac{1}{n} \log |x_{n+1}-x_n|<0$, prove that $\{x_n\}$ is Cauchy sequence. My work: Let $a=\limsup\limits_{n \to \infty} \frac{1}{n} \log |x_{n+1}-x_n| <0$. Then, for every $\varepsilon >0$ there exist $N \in...

All composite number comprised of atleast two factor e.g 57 = 3 * 19 and 1 * 57 14927= 11*1357 = 23*649 = 59*253 = 1*14927 We can get to know 57 is a composite number , as the factor 3*19 is achieved, as below, from 11^2. The first factor reduces and the 2nd factor increases, till first factor...

Hi guys, Can you help me with my problem please? if a steel ball 10 kg falls from 1 metre (free fall) and hits a concrete beam, how can I solve a single degree of freedom system to get the impact force and compare it with the test? Acceleration of the steel ball is known (so impact force can...