Test Definition and 1000 Threads

Homework Statement A 50 KVA,6360 V/230 V transformer is tested on open and short-circuit to obtain its efficiency,the results being as follows: O.C.: Primary Voltage-6360 V, Primary Current-1 A, Power Input - 2 kW S.C: Voltage across primary winding-180 V Current in secondary...

Homework Statement ∞n=1∑(-1)n\stackrel{10n}{(n+1)!} Homework Equations The Attempt at a Solution I already found that the limit does equal zero by using the ratio test on bn. What I'm having trouble with is determining if it decreases or not. I know you can't take the derivative...

Hi all I am comparing the performance of two models and have calculated the coefficient of determination R squared for each. I would like however to test the significance of this value. The F test however requires that the number of degrees of freedom for each model. The trouble is one...

I am not sure if this is the right sub-forum to post this question in or not, if not I appologize for posting in the wrong place - it looked like the most likely forum to be the correct one. In a sci-fi book I was reading, the author talked about an 'artificial symbiote' being created by 15...

Hello everyone, I need to work out the flexural modulus (Ef) of a test specimen that is subjected to a 3-point bend test. I know that: Ef = L3m/4bd3. I have: Support Span(L)= 0.1m width(b)= 0.01m depth(d) = 0.01m Max normal stress σf= 98.1 MPa Strain (εf) = 0.0525 Max force (applied...

Hi y'alllll! Need some guidance on a little issue, As you very well know, european standards (ecss) exist for space systems but they are generally outlined for launch vehicles. Do specific standards exist for payload fairings? For example a test sequence is outlined for general space...

1. A 30kg box is placed on a 15° slope and a person pushes on the box up the slope to keep it from sliding. If the coefficient of static friction is 0.15, what is the minimum force that the person must exert to keep the box in place? Answer Choices: A. 273N B. 241N C. 33.5 N D. 64.7 N E. 294 N...

For when there is a negative test charge: The work done to get from infinity to r would be negative, corresponding to a decrease in potential energy so since dr must be a path element and therefore in the negative direction (towards the source of the E field) does that mean the...

When considering tempered distributions, I am only aware of the definition of test functions of a real variable. However, is it okay to use test functions of a complex variable z that are analytic in a strip that includes the real axis? (of course they still must fall off fast enough as the...

Homework Statement Ok, so in a lab I was preforming Izod impact tests on notched polymer specimens. To complete my calculations I need to determine the correct cross-sectional area to use (Which is baffling me as the simple things usually do) The sample was loaded with the notch facing...

I need help deciding which AP Physics test to take. Currently, I am a junior taking AP Physics BC, which my teacher claims is between AP Physics B and C. It looks like all we will learn this year is mechanics, maybe touch on electricity. Our teacher isn’t giving us any AP test questions or...

Homework Statement Determine if the following series is divergent or convergent: ## ∑_1^∞ \frac {(2)(4)(6)...(2n)}{n!} ## 2. The attempt at a solution I understand this can be simplified to: ## ∑_1^∞ \frac {(2^n)(n!)}{n!} ## This can easily be seen to be divergent. But when I...

Null results so far for the elusive gravitational search, but were they expected to be found at this range? arXiv:1402.4974 (cross-list from gr-qc) [pdf, ps, other] Implementation of an F-statistic all-sky search for continuous gravitational waves in Virgo VSR1 data J. Aasi, B. P. Abbott, R...

How does one derive the second derivative test for three variables? It's clear that D(a,b) = fxx * fyy - (fxy)^2 AND fxx(a,b) Tells us almost all we need to know about local maxima and local minima for a function of 2 variables x and y, but how do I make sense of the second directional...

Looking for ideas... At my work, we test a number of products that come with flying leads, using this kind of connector: http://www.digikey.com/product-detail/en/33-1404/GC400-ND/258507 I'm looking for something a little more durable. These things have plastic clips to hold the leads in the...

In one case I get the results as a significant difference in the other with the same dana, the difference is not significant. Data sample A B I 5 8 II 4 28 http://imageshack.com/a/img542/467/o61k.jpg Same data and got significant difference...

Homework Statement If z is east and y is north then x is? A. West B. East C. North D. South E. Down Homework Equations I have trued getting the proper orientation but the direction I would have obtained is not an option 'up' a comment would be appreciated The Attempt at a Solution

25 questions, multiple choice, 5 choices per question. Correct = 6 points blank = 1.5 points wrong = 0 points. I should know how to do this, but have a cold and simply can't wrap my head around it… Danke Schoen!

Hello guys, I was searching for what voltage does IEC standard call for Di electric test that should be done to low voltage panels? is it 2.5 KV for 1 minutes? If yes how how low voltage cable rated 600/1000 V can withstand 2.5KV without insulation failure?

Hello, I was trying to interpret the formula of Pearson's Chi-squared test: \chi^2 = \sum_{i=1}^{n} \frac{(O_i - E_i)^2}{E_i} I thought that if we assume that each O_i is an observation of the random variable X_i, then the above formula essentially considers the sum-of-squares of n...

Homework Statement Use $$\sum\limits_{n=1}^∞ \frac{1}{n^2}$$ to prove by the comparison test that $$\sum\limits_{n=1}^∞ \frac{n+1}{n^3} $$ converges.Homework Equations $$\sum\limits_{n=1}^∞ \frac{n+1}{n^3} \equiv \sum\limits_{n=1}^∞ \frac{1}{n^2} + \sum\limits_{n=1}^∞ \frac{1}{n^3} $$ The...

Homework Statement Hester suspected that a die was biased in favour of a four occurring. She decided to carry out a hypothesis test. When she threw the die 15 times, she obtained a four on 6 occasions. Carry out the test, at the 5% level, stating your conclusion clearly. Homework...

Homework Statement $$\sum\limits_{n=1}^∞ \frac{1}{n√(n)} $$ Since $$ \frac{1}{n√(n)} \equiv \frac{1}{x^{3/2}} $$ this is a convergent p-series. But, when I attempt to prove this by the limit comparison test with known convergent series such as $$\sum\limits_{n=1}^∞ \frac{1}{n^2}$$ ex...

Hey, not too sure about what function i would compare this integral from 1 to infinity of (3x^3 -2)/(x^6 +2) dx. I also have to show that it converges. Thanks!

http://arxiv.org/abs/1401.6562 This looks very interesting, they are claiming a potential test for quantum gravity . What do we think?

So Thursday we had our first big test in class. I had managed to ace everything in the homework leading up to the test. I got cocky, and then I ended up bombing the test. I rushed through the test and completed it in about half the time I should have. The teacher offers a review with each...

This is technically a "homework" type question so I just need a bit of help. I'm just learning maple and writing a very basic procedure. I'm testing primality exhaustively by using the mod function. (Yes, maple has a built in procedure for this, but this is just an exercise). ISPRIME...

Homework Statement Question 1 Which statement is true of the coefficient of static friction? Answer It is the force resisting motion. It is proportional to the static friction force. It is a dimensionless quantity expressing the ratio of limiting friction to normal reaction...

Hey I've been lurking on this forum all day trying to find answers / help to problems I can't solve in my calculus text. So I finally got the bright idea to make an account and ask questions :) Although first I want to mention that I'm very rusty in math so I may need the special step by step...

Homework Statement Let ##X_1, ... , X_n## be iid normally distributed random variables ##N(\mu, \sigma^2)##, ##\mu \in \Bbb{R}##, ## \sigma^2 > 0##. a) Design a uniformly most powerful test with significance level ##\alpha## for testing ##H_0: \sigma^2 = \sigma^2_0## vs ##H_1: \sigma^2 >...

Something I've wondered about the Double Slit Experiment is what happens to photons which fail to pass through either slit, and what is their behavior? Why not put some detectors on the source side of the slits during a double slit experiment to try to determine whether the photons are...

I just had a interview yesterday and found that every student must pass the swim test once they get into MIT, is this true? Is the swim test hard? What if I don't know how to swim at all? What should I do then?

Hello, I am posting this here becase this is not a homework, it;s just something I need to know. Please tell me what these two waveforms mean? I know that they're both lightning impulse waveform but what is the difference between those two, what gives them their shapes?

FDA examining antibacterial soaps, body washes http://www.cnn.com/2013/12/16/health/fda-antibacterial/

Hi there , I have two cast iron crankshafts for an engine I'm building , now even though they are similar in every way , made ofr the same engine etc etc, there is one thing I noticed different and it got my attention , I took a stainless steel screwdriver and hit each one of the cranks at...

I'm going to try my first chemistry experiment. http://www.chemteach.ac.nz/investigations/documents/chloride_mohr.pdf I bought 35g of potassium chromate and 5g of silver nitrate. 5g of silver nitrate is only enough for one test. What should I do with the silver afterwards? Is it...

I was searching the internet for information on Bell tests, when I found an article entitled "Taco Bell tests grilled stuffed nacho." Does anyone know how the stuffed nachos are used in Bell tests? http://www.huffingtonpost.com/2013/10/11/taco-bell-grilled-stuft-nacho_n_4086345.html...

**g_{ij} = ** **g^{ij} = ** **\Gamma_{ij}^{k} = ** <tex>R^{i}_{jkl} = </tex> <tex>R_{ij} = </tex> <tex>R = </tex> <tex>T_{ij} = </tex>

Homework Statement An incompressible fluid with density ρ is in a horizontal test tube of inner cross-sectional area A. The test tube spins in a horizontal circle in an ultracentrifuge at an angular speed ω. Gravitational forces are negligible. Consider a volume element of the fluid of area...

Hey guys. I am having some trouble visualizing one aspect of the Second derivative test in the 2 variable case (related to #3 below). Essentially, what does the curve look like when f_{xx}f_{yy} > 0, BUT f_{xx}f_{yy} < [f_{xy}]^{2}? To be more detailed, if the function is f(x,y), H(x,y) is the...

Homework Statement Does \sum_{n=1}^{\infty}a_n where a_n = \frac{(n+1)^{1/3}-n^{1/3}}{n} converge or diverge? Homework Equations The Attempt at a Solution The ratio test is inconclusive, as is the root test. The limit is equal to 0, but that doesn't say much. I've tried to find...

Hello, I'm creating a musical device which has stainless steel bars cut with a laser cutter. They are all the same length but vary in width. I created a set of test lengths (50 in total) and tested the pitch of each one using a tone analyzer. Now I'm looking to fit a curve to the data so...

Homework Statement Test the series for convergence or divergence Homework Equations A_n = Ʃ 1/(2+sin(k)) from k = 1 to ∞ The Attempt at a Solution I looked at this and I thought that sin(k) does not have a limit as k goes to infinity. So I was thinking that Lim k--> ∞ A_n =...

Homework Statement We threw a bunch of darts at a dart board to find the statistics of the positions. They ranged from -20 to 20 and the data is right here. ( each column corresponds to the dart number, it is just a syntax thing) The frequencies are below. Dart 1 Dart 2 Dart 3 Dart 4...

Homework Statement Homework Equations ƩMA = Ʃ r x F Total Force of x,y= 0 root(rx^2+ry^2)= Magnitude The Attempt at a Solution I cannot find i) my method 0=2000+3000(0.4)-Rc -3200N=-Rc(up) 0=3200-2000-3000+Ry Rx=1800 How to find to magnitude, when roller only got...

I'm getting a bit confused with the stats of a chi squared test, everyone in physics labs seems to use this as a test but I don't know why it's appropriate? My main question is how would I take a linear equation in say excel which has been fitted to a series of (x,y) data points (I do have...

Homework Statement http://i1345.photobucket.com/albums/p679/Duk_Bato/Untitled_zps84f60bfd.png Homework Equations ƩMA = Ʃ r x F The Attempt at a Solution 1.6 * T+ 0.8 * sin 40 *T = 1.2 * 250 T (1.6 + 0.8 * sin 40 ) = 300 T = 300 / ( 1.6 + 0.8 * sin 40 ) T = 141.9 N RX=...

Hi, I was wondering how I might make my own nitrate test strips. I am not really sure how/if they are any different from normal red/blue pH strips. I am looking for a way to compare nitrogen content in different soils. I know they make cheap kits, but I was hoping there was a way to do it...

I've got 3 problems that I got wrong on my most recent test (college 1st year physics). I need to figure out what I did wrong and hopefully someone here can help me. I know all my answers are wrong because I got marked wrong but I'm unsure why, or if there's another way or a better way to go...

Homework Statement Use the Limit Comparison Test to determine if the series converges or diverges: Ʃ (4/(7+4n(ln^2(n))) from n=1 to ∞. (The denominator, for clarity, in words is: seven plus 4n times the natural log squared of n.) Homework Equations Limit Comparison Test: Let Σa(n) be the...