Measure Definition and 1000 Threads

In this project, I am using the https://www.amazon.com/dp/B005W09XYW/?tag=pfamazon01-20 as a power supply, but in my project, if my device shuts off suddenly without shutting off properly, it would require me to reboot the entire system as it won't work anymore. So I decided to use this power...

Hi all, I am not a physics major and have spent some time learning via the university of Google. I would really appreciate a second set of eyes on what I am calculating and tell me if I am correct, or if I have done something wrong along the way. I am trying to calculate MOI and need results...

How would you approach a most accurate measurement of the "length" of a coastline?

I was not sure where to post this so decided to start here. If there is a better section please let me know... If you put a sealed device on a scale and place in an air tight box then fill with air pressure would the weight change of the device if there was a leak? I am trying to do a test to...

I was not sure where to post this so decided to start here. If there is a better section please let me know... If you put a sealed device on a scale and place in an air tight box then fill with air pressure would the weight change of the device if there was a leak? I am trying to do a test to...

A cone with base radius $r$, vertical height $h$ and slant height $l$ has its curved surface slit and flattened out into a sector with radius $l$ and angle $\theta$. By comparing the arc length of this sector with the circumference of the base of the cone, show that $l\theta = 2\pi r$, and...

I have that the energy density of matter approx 0.3 , so this is measured by galaxy motion / gravitational lensing etc, that's fine. I have that the energy density due to the vacuum is 0.7, so this is measured by the expansion rate- the common suspect being dark energy. I have radiation...

Homework Statement Quantities without unit of measure are: A) Necessarily scalar B) Necessarily vector C) Can be scalar or vector D) They are neither scalar nor vector Justify your answer!Homework Equations No equations The Attempt at a Solution For example, the refractive index of a medium...

I am a software engineer. I am working on an experimental project to attempt to measure in real time the variation in air pressure (relative to the ambient pressure of the room) in a piston style apparatus. In this model, I am expectant that there will be a measureable change in the internal...

I have connected the probe to secondary of ring type CT and placed a wire as primary with one multi-meter connected at both ends. When I am checking the probe ends, its 7.1V AC, but it reading 45mV AC when connected to CT. Why this is happening?

So I have been researching, I'm no genius, on how to measure the force of a moving object. Now I have seen some of the equations and Newtons law and all but what I am specifically trying to do is figure out the impact force of an arrow. eventually this will be calculated into how much force of...

I read posts from a few years ago regarding measuring frequencies in the human body. I am wondering if there are any new developments. What devices can measure frequency? Thanks!

In my textbook it says:"in the hot-wire ammeter the pointer stands at a definite reading when the temperature of platinum-iridium becomes constant and the wire stops expanding. That is achieved when the rate of heat radiated by the platinum-iridium wire becomes equal to the rate of heat...

Hi there, As currently work for company that builds mobile apps I am looking into a way to measure whether a smartphone is outside a 5 meter range. As I am not an engineer I hope your expertise can help me out in order to come up with a right direction for further research. NFC, RFID, GPS...

Hi, I had a quick question about something from Section 3 of Srednicki's QFT book. In it, he's discussing the solution to the Klein-Gordon equation for classical real scalar fields. He gives the general solution as: $$\int_{-\infty}^{+\infty} \frac{d^3 k}{f(k)}...

How is the constant used to measure resistance? I can't find a clear answer anywhere. The constant is h/e^2 but that doesn't really help in seeing how it is linked to resistance other than the units being the same in base units.

I was quite distraught knowing that chegg.com has no textbook solutions for "measure theory" even though it has four for abstract algebra. Could it be that the textbooks are called something else?

The question is in the title. However my mathematical ability is limited as I am a high school student. Thank you in advance

Why do physicists use the word measure? We determine the location of a particle by measurement. Before measurement it doesn't have a location. If there wasn't a measurement conducted, then it wouldn't have a location in the first place. Therefore, measure should not be the term used. Wouldn't...

I am reading papers about dark matter and MOND. As they often mention this effect, I wonder how they know / measure / quantify how much gravitational lensing a particular galaxy causes? Thanks.

How can we measure Fragmentation/ discontinuity in a system?

Homework Statement . Suppose an electron is in the spin state (a,B) If sy is measured, what is the probability of the result h/2? Homework Equations Eigenvectors of the pauli matrix for y are (1,i)/Sqrt[2] (1,-i)/Sqrt[2] and if you are given a wave function of the sort a | +> +b |-> then the...

I don't remember seeing this solution to the question. Imagine an object of length d with a reflector on the far end (x=4). A moves past the object at speed a, emitting a signal at the origin in the positive x direction. A makes one pass in the +x direction, reverses and makes one pass in the...

Someday, mankind will be able to construct rockets that can move at relativistic speeds. The acceleration is given by ##a=\frac{F_0}{γ^3m_0}## ##F_0## can be easily measured by placing a force gauge on the rocket itself. The acceleration is much harder to measure, is has to be measured in a...

It seems to me that we don't measure a particle because a particle doesn't have an objective existence independent of the wave function or does it? The wave function in this case would have to be real because you can't have probability without the underlying possibility of a specific outcome...

In another math thread https://www.physicsforums.com/threads/categorizing-math.889809/ several people expressed their opinion that, while statistics is a branch of applied mathematics, the probability theory is pure mathematics and a branch of analysis, or more precisely, a branch of measure...

I read a paper on how a magnetic field of 4 T was used to break the van der Waals forces of an HeO molecule with a binding energy of 11.2 cm-1. I'll put the link to my original post below. Can someone tell me how this energy was measured? Your assistance is greatly appreciated...

This video explains the entropy concept as in terms of useless and useful energy. My question is how is this concluded from say Clausius' statement of 2nd law of thermodynamics which states that there can exist no cycle that transfers heat from A to B without producing any other effect. I...

Which instrument is used to measure altitudes in aircraft's

I could have formulated this in a few different ways, and posted it in different parts of the forum, but I think this is the most fitting one, even if I think that my question is more about time keeping. I recently watched an episode of Cosmos about Edmond Halley where parallax measurements...

In one of the experiments I give to my students, they need to set a burning candle at different (fixed) angles. In the past they have taped the candle to a cup and a needle taped to the cup like in the following picture. This is quite inefficient because for the same angle they need to tape and...

Homework Statement Show that {[0,1]}^2-{\mathbb{Q}}^2 has jordan inner measure zero. Homework Equations Jordan inner measure is defined as m_{*}J(E)=sup (m(A)) where A \subset E E is elementary. elementary means a rectangular measure in n dimensions. The Attempt at a Solution I...

How is this done in practice? I know that in GR the gravity is believed to curve not only space, but also time, and this prediction has been confirmed somehow in practice. How can we measure that? Because as far as i know, there is no device that actually measures time, but instead measures a...

Hi, I am looking for a book for studying probability theory using measure theory. This is the first course I am taking of probability. Notions and theorems from measure theory are part of this course. As it turns out, this is a catastrophic disaster, and the textbook for this course is also not...

Dear All, I am trying to understand the concept of "entropy" in thermal engineering point of view. I have basic idea about "entropy" i.e. the change in entropy is used to determine the direction in which a given process will proceed. However following two more definition (of entropy generally...

The potential difference across an inductor is supposed to be zero, but a voltmeter measures it to be L*dI/dt. Also, if the p.d is zero then the electric field in the wires of the coil will be zero and in that case, why should charges flow at all? What am I missing?

I would like to study more about the notion of time in modern physics. In particular, I would like to understand better the following question: how does one measure the time in the early universe? To measure time one needs to have clocks. A natural choice to be used as clocks would be particles...

When we record the flux of a light coming to us from outer space, which light do we use? Do we use visible light or X-ray or UV? Or is it all? Or does it depend on what we're looking at?

In this video (), we first took the spectrum of a star and then of a galaxy which look like the following: However, what I don't get is: if we take the spectrum of a star and then of the galaxy the star is in, shouldn't it give me the same spectrum as they're moving in the same speed? And if...

As far as I know, when we use the spectrum of a star, we see where the absorption lines are and using this, we can detect the elements that are present in the star. We also measure whether those absorption lines are supposed to be for a particular element. But why is it not possible that the...

Let us define, as Kolmogorov-Fomin's Элементы теории функций и функционального анализа does, the definition of outer measure of a bounded set ##A\subset \mathbb{R}^n## as $$\mu^{\ast}(A):=\inf_{A\subset \bigcup_k P_k}\sum_k m(P_k)$$where the infimum is extended to all the possible covers of...

I am not a scientist or particularly good with math or formulas. I have been curious about this for a while, and would appreciate anyone clarifying/correcting me. I have a stainless steel container that can be heated up to 75 degrees celcius/165 degrees Fahrenheit in a bain marie. It can hold...

Hello, friends! Let us define the external measure of the set ##A\subset \mathbb{R}^n## as $$\mu^{\ast}(A):=\inf_{A\subset \bigcup_k P_k}\sum_k m(P_k)$$where the infimum is extended to all the possible covers of ##A## by finite or countable families of ##n##-paralleliped ##P_k=\prod_{i=1}^n...

Hi everyone, I'm trying to find a test to compare two assays, and I'm not sure which one I should use. Could you please help? Here's the situation. My company is setting up two assays, A and B. Both assays are supposed to measure the same property of certain items, i.e. we would expect A and B...

Hello, I would like to measure power from a photodiode. How do I go about doing this? What would the circuit look like?

Homework Statement To me it makes more sense to use force*time instead of force*distance. Because when you are aplying force to an object that isn't moving you're still wasting energy. Or when you push a weight over the same distance with little force or big force, the amount of energy wasted...

who was the first person to discover how to measure the wavelength of absorption lines in the solar or stellar spectra and what method was used?

Hi everyone, in this days i was seeing a little of Fourier series and transform, and i wondered if it was necessary to better understand before the measure and Lebesgue integral before studying it. Or it's not necessary?

I have to build a digital peak flow meter. I ve read that you can measure the volume metric flow rate using a differential pressure sensor. H ow do i go about doing so. The peak flow meter will be used to measure asthma.

Homework Statement Somebody knows an experiment to measure directly frequency of de Broglie waves?