Accuracy Definition and 224 Threads

Hi there! I wanted to ask you, we know that light, photons have a certain fixed speed generally. Wouldn't this imply, considering Heisenberg's uncertainty principle, that the uncertainty for the speed (momentum) of the photons, should be infinite? But we know for sure, for example, that...

Hello,in this link http://dtic.mil/dtic/tr/fulltext/u2/a028054.pdf a paper „Maximum Theoretical Angular Accuracy of Planer and Linear Arrays of Sensors“ can be found.The accuracies are given in equations 19 (respect to the x axis) and 20 (respect to the y axis).My question is: Shall the angle...

I'm in the process of writing a story and the first few thousand words take place near the head-on collision between a ten mile wide black hole and a really big star. I describe the star as big enough to swallow the sun and barely burp. I'd like the events to be as close to accurate as...

Homework Statement Which multimeter is more accurate? Homework EquationsThe Attempt at a Solution Which multimeter is more accurate, one that is ±1%+2 or one that is ±2.5%+2 I don't know how to read it, is it the higher percentage one that's more accurate or the lower percentage one? I think...

Homework Statement I am given a numerical example (to be solved with pen, paper and calculator only) of an RBS spectrum of a AuAgCu-alloy on a glass-substrate. The question is "Can you get the composition? How accurate is the result?Homework Equations All the Rutherford Backscattering...

Hi PF/math ! I've been searching for a program which will draw 3d parametric curves accurately for large variables, eg. f(10^8). Ive tried www.math.uri.edu and Ti-Nspire (the latter may or may not have a setting for the accuracy), but both tend to turn what should've been a smooth curve into an...

Hello! (Wave) We are given the boundary / intial value problem for the heat equation: $\left\{\begin{matrix} u_t(t,x)=u_{xx}(t,x), \ \ x \in [a,b], \ \ t \geq 0\\ u(0,x)=u_0(x), \ \ \forall x \in [a,b] \\ u(t,a)=u(t,b)=0, \ \ \forall t \geq 0 \end{matrix}\right.$ I have written a code to...

Hello! (Wave) With what order of accuracy does the divided difference $\frac{f(x+2h)-f(x)}{2h}$ approximate the derivative? I have tried the following: $$f(x+2h)=f(x)+ 2h f'(x)+ 2h^2 f''(\xi) , \xi \in (x,x+2h)$$ $$\frac{f(x+2h)-f(x)}{2h}=\frac{2h f'(x)+ 2h^2 f''(\xi)}{2h}=f'(x)+hf''(\xi)$$...

Homework Statement I need to find three potential reasons for my .5% error in a lab where I used the Archimedes Principle to measure the density of Iron. We only used a graduated cylinder full of water and an iron mass. I measured the water level from the meniscus. We used two different...

I noticed the scan was cut off on the second image at the bottom right, but I came up with x= 31/5 My first test in Calc I begins tomorrow and I want to know that I'm headed in the right direction. I think I understand to some extent how logarithms can be expanded and condensed though I'm...

Hello everyone; My transducer manufacturer says that the accuracy of the pressure measurement device is 0.5% in full scale of PSI. However, I don't use Psi but Pascal. Is it the same value for pascal as well? When I make measurement I will get 0.5% error in pascal too? Thank you.

I am trying to build a couple bicycle racks and need help confirming that I got the forces right. The area in question is at the bottom assuming the reaction force will be to the right for the matter of balancing the moment. It's been a while since I took classical physics, so please correct me...

Hello! (Wave) Suppose that we are given $h_1=0.1 \to \delta_1=0.01$ and $h_2=0.05 \to \delta_2=0.025$ and we want to find the order of accuracy of the method. I have tried the following: $\delta_1^n= c h_1^{p+1}, \delta_2^n=c h_2^{p+1} \Rightarrow p+1= \frac{\log \left(...

Hi, Let's consider the heat equation as \frac{\partial T}{\partial t}=\alpha \frac{{{\partial }^{2}}T}{\partial {{x}^{2}}} In order to have a second accuracy system, one can use the Crank-Nicolson method as \frac{{{\partial }^{2}}T}{\partial {{x}^{2}}}\approx \frac{1}{2}\left(...

I want to ask a strange question. When the gun has 10% accuracy, what does 10% mean? I mean it doesn't really tell me anything. How large is the area the bullets spread if the gun has 10% accuracy? I have already attempted to find articles in google, and I still didn't get the answer about the...

Hey, i am trying to teach accuracy and precision. I understand precision to mean two things. How repeatable measurements are (variation), and how specific measurements are (sensitivity). I am having a bigger problem defining accuracy. Most places i look define accuracy as how close...

Hey! I've a simple (and maybe stupid) question about the accuracy of an OSA. The datasheet report a level accuracy of 0.4 dB but this seems quite strange to me. Indeed level measurements are done in dBm thus, as long as dB measures a relative power, I assume that even the 0.4 dB are referred to...

Why is the Kelvin scale more accurate than the Celsius scale when a change of 1K is equal to a change of 1°C? It's something I've always wondered about but never looked into. (Apologies if the answer is incredibly simple. I'm still very new to the world of physics :smile:)

Homework Statement so let's say that we have a solution S=0.4±0.01/250ml i want to do a dilution so i pick 5ml and pour it into 100ml beaker how should i calculate precision of the solution (mathematically or with some other equations)? Homework Equations so basically we have F=5*S/100 The...

Hello, i have a optical signal(x is length in pixels and y is amplitude ) and i have found a number of FWHM values of peaks. The width is measured in pixels, let's say the average width of 50 peaks is 8,7 pixels, standard deviation is 0,6 and the average amplitude of peaks is 38 and standard...

I don't know very much about quantum mechanics, but if I'm correct, the future can not be predicted with certainty according to quantum mechanics. If this is true, how can we have formulas in classical mechanics that do predict the future with certainty?

Is there any law that prevents us from accurately measuring the momentum of a particle , just like the energy time uncertainty principle makes us observe the system for an infinite amount of time before we can be certain about its energy? I got this doubt because if we can do it, we will...

Homework Statement Charges +/- q separated by a distance d make a dipole with dipole moment qd. For large r the potential approaches qdcosθ/(4πε0r²). For θ=0, how large must r be so that the asymptotic function is accurate to 1%? Homework Equations Exact V= q1/(4πε0r) + q2 /(4πε0r) Approximate...

For example, I weigh a pebble and get a value of 7.1g. Then I measure again and get 7.6g, then again and get 6.9g.. Then I repeat the measurement using the same scale 5000 times. (its just a thought experiment). Is the mean of all measurements closer to the true value and if so, why? thanks

In my computational physics textbook, three different velocity estimators are derived for a problem with equation of motion: \ddot x = F(x) where the positions are found by using the Verlet algorithm: x(t+h) = 2 x(t) - x(t-h) + h^2 F[x(t)] The three velocity estimators are: v(t) = \frac{x(t+h)...

At a distance of 15 meters, is a pellet more accurate than a BB, or vice versa? Is a pellet more aerodynamic than a BB, and, if so, why?

hello everyone , i am clueless about electrical engineering and want to ask something this meter is based on orgone energy .. which is not accepted by science currently i want to ask is this meter fake ? then how is it able to get those different readings( which looks precise ) for...

Hey all, I need to build a launcher that is capable of throwing a tennis ball over a 1 meter high wall and hit a target 2 meters away. I realize there are some threads already discussing this, but my question is more based on the type of launcher. Would a trebuchet or a spring powered cannon be...

Good afternoon! Suppose I have a box with N marbles of different color and I want to know the ratio of the number of green ones to N (number X). The number of marbles (N) is so huge that there`s absolutely no way to get them all out of the box and count. What I do instead is I take a sample of...

With another microphone? And how do you test the accuracy of that microphone? With yet another microphone? ...and on and on we go I suppose you're probably thinking to yourself, "well that's easy BeautifulLight, just set up an experiment using a signal/tone generator, couple of microphones...

I have been out of unversity statistics and biometry for a few years do date. I am working in a clical research facility and we are comparing two methods of microbial identification and am now working on the results / charts / statistics. Forgive me for my ignorance, but I am forgetting which...

By combining the two equations i should be able to solve for u' and get rid of u'': u_(i-1) = u_i + (-h)*u' + 1/2 * (-h)^2 * u'' + O(h^4) u_(i-2) = u_i + (-2h)*u' + 1/2 * (-2h)^2 * u'' + O(h^4) But i keep getting stuck and can't come up with the answer below. Can anyone help me please...

Hi, the accuracy of interferometers for finding emitting direction in one direction is given as: Δθ = Δφ•λ/(2pi•l•cosθ) but what would it be if two dimensional accuracy is required, something like interferometer in crossing? I thought this could be found somewhere in Internet, but I...

What would happen to the accuracy of a float gauge if the fluid it is measuring is heated?

Hello all, If you have been watching the olympic games lately you could have seen that in the past week it has occurred twice that an athlete won (and another lost) a gold medal by a time difference of a few 1000th of a second. Both occurrences where in speed skating (i.e. the 500m and 1500m...

I was looking through a textbook, and read that the value of g was determined to be exactly 9.80665 ms-2. I just started wondering why do we need to know it to that accuracy? Was it necessary for certain experiments? Or did people just want to know? Then I started to think about why we might...

I have a general question about the solution to the Diffusion equation using the explicit finite difference method. Now, it is known the solution is stable when D*dt/dx^2 is less than 0.5, based on the choice of time and space steps. However, how does the choice of the time and space steps...

I was a member here years ago and recall the excellent quality of the brain trust present and I need some brain power to give me some understanding of the situation I find myself in. Through a series of unfortunate events, the woman I was seeing had a brief encounter with another man. Here were...

Hi friends, I search after examples or videos or names of robots or machines that work in a very accurate scale something like one millimeter of accuracy or better accuracy, so if you know about a robot or machine that work very accuracy so I will glad if you can write this in this thread.

Aside from accessibility/affordability reasons why aren't students allowed to use technology in exams? For example why is it so uncommon to be able to use a computer algebra system? The only reason I ever heard was from my elementary school teacher is that you don't want to put all your trust in...

Homework Statement Calculate Z1=5+j10 Z2=10+j8 Z3=10+J5 RL=40 V=100 VTH=VX(Z2/Z1+Z2) ZTH=Z3+(Z1Z2/Z1+Z2) I=VTH/(ZTH+RL) IL=? Homework Equations My question is what calculation method is more accurate: First to convert complex numbers in polar forms, and then calculate or calculate complex...

I have a dosing pump spec. sheet from Milton Roy (a fairly reputable manufacturer) which says: Steady State Accuracy: +/- 1% Repeatably: +/- 3% Is this possible? Can an instrument be more accurate than it is repeatable? Intuitively, this didn't make sense to me. The spec. sheet...

Hi, I just took an IQ test, http://sifter.org/iqtest/ It relates the European IQ test to that of the Stanford-binet test. I just did it, but I was rather depressed and self-loathing, so maybe I could of done better... lol. I also was not aware of the time I was spending, perhaps better...

I have an instrument whose spec. sheet mentions Accuracy as 2% of FSD. The scale runs from 0 to 1000 Litres per hour. Does this mean if I check the instrument versus a gold standard calibrating instrument at a flow of 500 Litres per hour (which is our typical flow) the absolute error can be...

Suppuse I'm making a measuring device of some sort that gets its feed from a microcontroller, would there be a huge difference between 8bits, 16bits, and 32bits microcontroller in terms of the device capability to measure accurately? Like, I imagine, the 8bits could only measure jumps of 0.5mm...

I'm writing program in which I generate pseudo random expressions with the hope of finding one that closely approximates the given data set. The functions map from R^m (an m-tuple of reals) to a real. What I need is a way to rate the functions by their accuracy. Are there any known methods for...

i just want to understand what i read in my algebra book. here what it says: a measurement of 83200 ft. converted to (8.32)x10^4 ft. is now accurate to the nearest hundred feet. if we write (8.320)x10^4 the measurement is now accurate to the nearest ten feet. i want to know why it is nearest...

I'm refreshing my knowledge of calculus and ran into this problem while working on limits. "Find∗ the value of each of the indicated limits to at least 3 digits of accuracy by evaluating f(x) at various values, or state that the limit does not exist (DNE)." My problem is with "at least 3...

Homework Statement http://img853.imageshack.us/img853/5578/euler.png Homework Equations y_(n+1)=y_n+f(x_n,y_n)h The Attempt at a Solution With n = 100 and step size h = 0.01, I got y_100 = 3.1515 I don't see how this is right, because the directions imply that it's supposed to be accurate...

Hi, I would like to use a Hall Sensor (e.g. http://fwbell.com/Category/2.aspx) or a Hall Element IC, like the AD22151 device for magnetic field measurement with a range from 0 to ca. 0,5 mT with a resolution of 250 nT. (500 ppm) The temperature fluctuations are max 1 C. Do you think I can...