Measurements Definition and 382 Threads

I came upon a very interesting article today: http://www.msnbc.msn.com/id/19875410/site/newsweek/ I wanted to confirm what I read... this is the first time I ever heard of this kind of thing, and I was wondering if any of you have seen this before. It talks about a tweak of Young's...

Used in measured highs/lows/hourly temperatures. Are they shade temperatures or temperatures under the Sun? Also - are shade temperatures really cooler than temperatures under the Sun?

Hi just got a couple of question about errors in measurements. I have a table of results of different meter stick measurements which are accurate to 0.1 cm. Now a meter stick reads to 0.1 cm and the uncertainty is usually 20% of the smallest reading. so all of my readings should be +/-...

Hi. If I have got it all right the latest measurements of light from very distanced super novas tells us that the space of the universe is not curved, either hyperbolic or Spherical. But I have recently been introduced to diffrent kind of hyperbolic geometries, like the projective model for...

I just read a news on physicsweb: http://physicsweb.org/articles/news/11/3/9" This is called a "quantum non-demolition (QND) measurement on single photons". I would like to know a little bit more about QNDs. Why they are called so. What is special about these QND experiments, or maybe...

I am taking measurements off the screen of an analog oscilloscope in order to calculate voltage and frequency of a sinusoidal wave form. The volts per division is set to 0.50V, and the time per division is set to 0.50 ms. I measure the vertical length of the trace to be 2.67 divisions. I...

I am writing a report on an experiment involving measuring the resistance of one component with different multimeters, and finding the uncertainties of these measurements from the multimeters themselves. For example, with one of the multimeters I got 270.1 ohms. This multimeter have stated "0.7%...

This is a question about practical physics ... if its posted in the wrong section my sincere apologies ! How do i decide the least count of a measuring device such as an ammeter (analog) ? I know that the least count is the smallest division of measurement ... but why do people...

I'm doing test corrections for homework and we have to explain how to correct what we did wrong. I already have the answers I just need to know how to figure out the answer. 18. Find m<Q. The diagram is not to scale. http://img100.imageshack.us/img100/3986/helpbp3.jpg 24. Find the value...

Hi, I just had a quick question in regards to the addition/subtraction of quantaties and their uncertainties. Am i correct in saying (22.4mL plusminus .01mL) + (21.3mL plusminus .01mL)=43.7 plusminus .02mL? or is it plusminus .01mL ? Im pretty sure my first answer is correct just...

Was the QM postulate for measurements misleading? Interactions and their understanding is the central topic of QM. So it is for CM too. The interaction between a QM system and a (macroscopic) Classical system is for sure an extremely interresting subject. Particularly when we want to describe...

Suppose you have a particle which is not in a momentum eigenstate. You then measure the momentum (say, in the x-direction) by two separate apperati simultaneously. Do the results have to agree? I asked my professor about this and he said that quantum mechanics will tell you that you can't...

Has anybody seen the news on the new measurements of the Bs - anti-Bs mixing amplitudes by the D0 and CDF experiments at Fermilab? Tommaso Dorigo has a scholarly description at http://dorigo.wordpress.com/2006/04/11/more-details-on-bs-mixing/" (you may have to scroll down to April 19 there...

what two measurements are made of an element using a mass spectrometer?

Hi, I really need help solving this problem, can you pleasez help me with it? Here is the problem: An operator A, representing observable A, has two normalized eigenstates w1 and w2, with eigenvalues a1 and a2, respectively. Operator B, representing observable B, has two normalized...

i have some boubts about uncertainty in physical measurements. when adding two measurable values or subtracting them, we ADD UP the uncertainties-that is understood. BUT when multiplying two measurable values WE ADD PERCENTAGE UNCERTAINTIES. Why is that?

Hey for a project, i have to build a sensor of any sort, and then make loads of measurements to see how accurate it is ect, what do you think would be a good sensor to build. it needs to be complex but not extreme! i am in 6th form takes A.s physics! any ideas would be greatfull. thanks alex!

The question is "two operators A,B do not commute". Is it true that ([A,B]psi) does not equal zero for any state psi?" I'm not sure if there are any cases in which a state psi could produce this result (except for the obvious one where psi = 0 and there is no particle). Thanks

I need to calculate a spring constant using measurements from a Hooke's Law Apparatus, a spring, and some weights. Frankly, I have no idea what I need to do. I've taken the measure ments, and discovered the formula F=kx, where F=Force, k=spring constant, and x=the compressed distance. I'm not...

This is my report on an experiment that I have done and I really needed the latex codes to generate the equations. I have done the other parts of the report on other PC. Do they seem to be ok? (the errors, like the max possible value and min possible value) no help is really needed, rather...

One problem in past climate models has been that the troposphere did not appear to be warming as much as expected. A new report in Science indicates that a correction factor should have been applied and was not. When the correction factor is applied, warming in the troposphere is observed. I am...

Hi, I just started my school year, and we're currently on Measurements. I need help with this one problem that my teacher assigned. The biggest bottle ever made was 193 gallons (730,505cc). If the bottle were filled with water of a density of 1000 kg/m^3 at the leisurely rate of 1.8 g/min...

I'm just starting to learn about relativty, and I'm having trouble understanding it. Maybe someone could help? The first thing that I'm have trouble grasping is why would measurements of time/distance be dependent on an object's velocity relative to the speed of light?

Hi! I have to make a presentation about the usage of lasers in measurements, but I am not sure what I should include. I thought of something like using laser beams for measuring distances, but I don't know how exactly this can be done and what else can be measured with lasers. I'd be greatful if...

Is there a site that teaches how to do conversions of measurments. More specificly I need one that teaches coversion between different measurements like gallons to cubic inches or square feet to millimeters or grams to meters LOL if there is such a thing lol

Hello all I need help with the following problem: Two measuring sticks use the same unit but the scale on one stick has 635 marks per unit and the scale on the other stick has 465 marks per unit. Suppose the sticks are placed together so that the 0 mark on each scale line up. What is the...

I'm having difficulty with one problem and was hoping someone could help me out. Here's the problem: Mercury is poured into a U-tube as in Figure P14.18a. The left arm of the tube has a cross-sectional area A1 of 107.0 cm2, and the right arm has a cross-sectional area A2 of 4.10 cm2. One...

The four bell states are 1: (|00>+|11>)(2)^-0.5 2: (|00>-|11>)(2)^-0.5 3: (|01>+|10>)(2)^-0.5 4: (|01>-|10>)(2)^-0.5 I'm looking at super dense coding and the way i thought of it at first was that if a measurement of the first qubit was made then if we consider the first bell state (1)...

In class today we had a brief lesson on vector addition. I understand how to calculate the resultant when given a magnitude and angle measurent for each vector, but my teacher gave me no other examples. I have tons of homework problems that do not give me this information, but I am expected to...

I need help converting feet to area or square feet for my horse stall. I have two stalls, each of which is 12' x 12'. I want to put a thickness of 2.25" of lime over the barn floor surface of these stalls. How many 50 lb bags would I need to buy? Can you show me the equation also? Thank...

Hi! I'd like to make some half-life measurements on water based foams. I have only simple instruments for it. Can anybody help me? I don't know the exact method that how to make this measurement correctly. And I also need the mathematical apparatus for it. I've found an article where the...

Say you have two measurements of the same quantity: t = 500 +- 20 +- 3 t = 600 +- 90 +- 10 where the first error is statistical and the second is systematic. What is the correct way of combining the systematic errors? i.e., if I want to put both measurements together into t = x +-...