Measure Definition and 1000 Threads

  1. R

    How did 19th century scientists measure atomic and molecular weight?

    Found myself wondering about this recently, though I can't recall the context. When Mendeleev proposed the periodic table of elements, I believe that it was known that atomic weights of the known elements were multiples of hydrogen's atomic weight. Presumably also with substances like oxygen...
  2. K

    How to measure the Sun's acceleration relative to the galaxy?

    How would the acceleration of our sun relative to our galaxy be determined? A spaceship in orbit around our sun, with engines turned off, is in free fall. Accelerometers will read zero. Turning the engines on, the accelerometers will read the acceleration due to the thrust from the engines...
  3. B

    How to measure water flowing from a washing machine pump?

    Hi all Am trying to find a way to measure the vol/time flow of water from the washing machine. Is there an electronic component that can be used like a coil of copper wire over the tube and the do something with a microcontroller perhaps and it figures out much flow? by electromagnetic...
  4. F

    Why can we only measure energy (enthelpy) change?

    Hello, I asked this similar questions on a different thread but it may be more appropriate for the chemistry forum. What is the reason we can only measure energy "changes" and not the actual energy value associated with a system? Absolute energies and enthalpy cannot be determined but I am not...
  5. JulioHC

    How to measure the magnification of a microscope in the lab

    Good evening, In the following weeks, I will be performing a lab project during three sessions and one of the things that I have to do is to create a microscope using a set of lenses (We are using a 50mm focal length convergent lens as the objective and a 100m focal length convergent lens as...
  6. Abdullah Almosalami

    How to measure the reactive part of output impedance?

    Given a sinusoidal voltage source attached to a load, like the following, I want to get both the resistive ## R_o ## and the reactive ## X_o ## components of the output impedance ## R + jX_o ##. Measuring the open circuit voltage will give ##V##. If I connect a test resistance ##R_1## at the...
  7. gmastrogiovanni

    I Do I need energy to measure position without uncertainty?

    I state the following study and then expose my doubt at the end. MY SYSTEM A free particle (absence of forces) on one-dimensional space (X axis). INITIAL STATE At t=0 the wave function is a Gaussian wave packet NOT normalizet centered in ##x_{0}## and with standard deviation ##\sigma##...
  8. Pericles98

    I Exploring Proper Time: How David and John Measure Time Differently

    Hello everybody, I've just started studying special relativity and seem to be having a bit of a problem with understanding the concept of proper time. In Modern Physics, by Serway, proper time is defined as the time interval between two events as measured by an observer that sees both events...
  9. F

    A How to measure the first qubit in two qubit system? QC

    I was wondering how to measure the first or even the second qubit in a quantum computing system after for example a Hadamard Gate is applied to the system of these qubits: A|00>+B|01>+C|10>+D|11>? A mathematical and intuitive explanation would be nice, I am a undergraduate sophomore student...
  10. F

    How does a digital multimeter measure conductance?

    Preface to thread: Back in October I created a thread titled "How does a digital ammeter work?" That thread was about how digital ammeters measure current. The purpose of this thread is to learn how digital multimeters measure conductance, not voltage. This is a separate issue for 2 reasons...
  11. TheQuestionGuy14

    B Can you measure a particle without breaking superposition?

    Is it possible to measure an electron, and, say, get multiple simultaneous results about it's motion, as you didn't break superposition? (E.g. you could simultaneously read 5mph, 10 mph and 15mph), and could this be used for quantum computers, to store store and gain huge amount of information...
  12. J

    MHB Lusin's Theorem - Infinite Measure and not Real-Valued Extensions

    Lusin's Theorem: Let $f$ be a real-valued measurable function on $E$. Then for each $\epsilon > 0$, there is a continuous function $g$ on $R$ and a closed set $F$ contained in $E$ for which $f=g$ on $F$ and $m(E - F)<\epsilon$. I'm going through exercises in the book... almost finals time. The...
  13. A

    How do I use full-bridge strain gauge circuit to measure F?

    Hey all, I am using a Wheatstone bridge with 4 strain gauges as resistors. I have a formula for the output voltage (Vout). My questions is how do I make it so instead of voltage I measure force? Do I simply apply a set max. force (let's say 140N), see what voltage I get (Vout,max) and then use...
  14. J

    MHB Measure Theory - Existence of Fsigma set contained in measurable set

    Problem: Let $E$ have finite outer measure. Show that $E$ is measurable if and only if there is a $F_\sigma$ set $F \subset E$ with $m^*\left(F\right)=m^*\left(E\right)$. Proof: "$\leftarrow$" To Show: $E=K\cup N$ where $K$ is $F_\sigma$ and $m^*(N)=m(N)=0$. By assumption, $\exists F$, and...
  15. Zahid Iftikhar

    Temp and Pressure measure of KE(average)

    Hi My question is related to interpretation of temperature and pressure in gases on the basis of kinetic molecular theory. According to it, both temperature and pressure are proportional to average translational kinetic energy of the gas molecules. Now in a situation where an ideal gas in...
  16. L

    How to intuitively understand Voltage and how to measure it?

    I am trying to get a better intuitive understanding of voltage and how it is measured. Here is my understanding: Voltage shows the potential difference between 2 points in a circuit and a higher voltage correlates with a higher electromotive force (emf) that moves the electrons through the...
  17. G

    Two voltmeters in parallel measure these different voltages

    Homework Statement I'm currently studying induction law and circuits with inductors. I came however with the following circuit: [1]: https://i.stack.imgur.com/ghaiE.png Homework Equations 3. The Attempt at a Solution [/B] Now my text says the following: "Unlike what your intuition might...
  18. wirefree

    Can a microwave VSWR meter be used to measure Power?

    G'day. Recently we conducted an experiment in the microwave engineering lab where we were tasked to measure power in, what's called, a Directional Coupler. Here you'll find much on it. My concern with the setup is that we took our measurements on a VSWR meter by noting off the db scale. So...
  19. StillLearningToronto

    I General Q: How do you measure a Galaxy's distance?

    If I am given the variable of time (observed), and diameter is it possible to measure the distance of a galaxy? Or do I need more variables? Just trying to figure out the most simple way to go about doing something like that.
  20. prashantakerkar

    Measuring the weight of gas in an inflated balloon

    What could be the method for measuring weight of gas in inflated balloon? Thanks & Regards, Prashant S Akerkar
  21. mertcan

    A Why Is the Measure of a Nonconvex Hessian Matrix Convex?

    Hi, initially I would like to share this link: https://books.google.com.tr/books?id=gWeVPoBmBZ8C&pg=PA25&lpg=PA25&dq=matrix+measure+properties&source=bl&ots=N1unizFvG6&sig=kxijoOVlPAacZDEdyyCwam4RQnQ&hl=en&sa=X&ved=2ahUKEwjd7o-Ap53dAhWJGuwKHdRbAO04ChDoATABegQICBAB#v=onepage&q=matrix measure...
  22. M

    How Can I Measure Arm Trajectory Using 2D Pixel Coordinates?

    I am not sure in which section this question should belong so I am placing it here for now. I have no experience in physics and body motion so appreciate some patience with my question. the information i have are pixel coordinates of the head, shoulder, elbow, hand, knee, hips and leg of 2...
  23. Suppaman

    B Calculate, not measure the value of c

    Recently I watched a youtube video about the speed of light and how it was not about light. I was wondering if the value of C can be determined instead of measured. Is C a constant in some formula that has well-known parameters and so the value of C can be calculated? I am just a science...
  24. Felipe Lincoln

    Why is displacement current difficult to measure?

    I had a question in my textbook asking why is the magnetic field generated by the displacement current in a capacitor more difficult to be measured than the magnetic field generated by the current in the wire. But I don't know how is this type of magnetic field measured, I only know that they...
  25. bob012345

    I How to measure the surface area of an arbitrary 3D object

    I'm looking for an easy way to get the surface area of an arbitrary shaped 3D object. Getting the volume is easy by water displacement. What about area? Any neat tricks? We know different shapes can have the same volume and thus different surface areas so it's not a trivial problem. The purpose...
  26. PhysicsBabexo7

    How to measure pulsations in a tube?

    Hey guys/gals so here is my problem, I am trying to be able to passively measure the mechanical vertical deflection of fluid passing through an elastic tube approx 1cm in diameter with 0.5mm thick wall that is embedded into the surface of a gelatin mold. Pressure of the flow through the tube...
  27. Monoxdifly

    MHB [ASK] Exact Measure Using Two Bottles

    Someone wants to take 4 liters of water, but he only has two 5-liters and 3-liters bottles. How is he able to measure 4 liters with only those bottles?
  28. PGaccount

    B "We cannot measure both position and momentum...."

    [Mentors' note: This thread's prefix has been set to 'B'] We all know that the quote in the title is an imprecise convenience when talking about the Heisenberg uncertainty principle in a context where we would not want to enter into conceptual or fundamental issues to make a more correct...
  29. W

    Length of time needed to measure digital clock accuracy

    On a piece of equipment, I purchased new, the digital clock ran slow. The second digital clock that was installed ran slow---it lost approximately 4.1 minutes in one month. Below is what I sent the Service Manager who I understand thinks it is possible to test the newly installed clock...
  30. Monsterboy

    Entropy as a measure of ignorance

    http://qr.ae/TUpoRU "Entropy is a measure of our ignorance about a system " Is that accurate ?
  31. M

    A How to measure emissivity of hot (~1000 centigrade) objects

    I want to measure the emissivity (or more correctly the absorbtivity) in the wavelength range 1 - 10 micrometer of very hot (~1000 degrees Celcius) ceramic materials. At room temperature this is typically done using an FTIR spectrometer with a gold coated integrating sphere. But for very hot...
  32. Andres Padilla

    How to measure the magnetic field/ induced fem in a system

    Homework Statement Hello, this is like an experiment of engineering.It is called a induction stove. The system consists of a bycicle, where I am going to pedal. This will turn a disk that have 20 small magnets around its circuference. Once the disk starts to turn, it will produce a constant...
  33. vukhanh97na

    Measure temperature without a microcontroller

    Hello everyone . I'm having a project about : Use thermorcouple to measure temperature without microcontroller(0 - 200 oC) . I researched and i think : " use opamp and icl7107 for display " . But i have 2 problem : - I can't amplify exactly signal from thermorcouple (because it's very small ~uV)...
  34. C

    Measure the max angle of a 3D pendulum

    Hi, I need a simple way to measure the maximum angle/vertical displacement of a 3D pendulum (weight hanging from a rope) undergoing random impacts. What will work?
  35. N

    B Is there a way to measure gravity in a particular area of space

    Dumb question probably -- But is there a way to measure gravity in a particular area of space, or a "measurement" .. I.E. the gravity 10 miles above Earth v.s 1000 miles above. Not force on another object, but some "unit" or measure of gravity itself.
  36. Miopen

    I How Can Muscle Strain Be Measured?

    I am trying to figure out if there is a way to measure muscle strain. If I apply a force F to compress a hand grip to the maximum distance x The work done to compress the hand grip is F*x Work done = Fx Since work done = energy used, I can change the equation to: Energy used = Fx When...
  37. curiousman

    Medical How to measure pain objectively?

    Hi! Are There other Objective Measures for Pain? Although we haven't yet come up with a cure for pain, we have long effective treatments such as opioids or acupuncture. However, when it comes to being able to evaluate pain based on solely subjective complaint from a patients, without...
  38. Irl495

    Minimum gas pressure to measure its volume with an eudiometer

    Hello, As you can see in the attached hand drawing+calculation, my question concerns the typical method of evolved gas volume measurement by water displacement in an inverted graduated cylinder or "eudiometer". Once a bubble (cavity to be precise) of gas leaves the end of the tube through...
  39. J

    Which way do I measure the potential difference

    Homework Statement All the bulbs in the circuits are identical, as are all the batteries. Rank the magnitude of the potential difference between points M and N. Homework Equations V=IR The Attempt at a Solution My most fundamental question is actually which way do I know to take the...
  40. fluidistic

    I Non-contact methods for measuring voltage in conductive materials

    Consider a solid material such as a conductor. I would like to know if there are ways to determine the voltage at specific spots on the material, without plugging a metallic wire and connect it to a voltmeter. I know voltage is relative and I'm interested in checking voltage differences across...
  41. P

    How to measure a magnetic field

    Hi, I hope that's the correct forum. So I'd like to play around with electronics and magnetism. Meaning: I'd like to build myself a electro magnet and then do some fancy stuff with it. Probably I'll try to recreate this...
  42. D

    Instrument to measure the frequency of sound

    I need an instrument to measure the frequency of the sound of a vibrating violin string for a high school research essay. I tried using a Labquest and a vernier microphone to measure but it was way too imprecise. I need the instrument to very accurate in measuring Hz as the nature of my essay...
  43. M

    I How do we measure the velocity of stars in a galaxy?

    I have read somewhere that the parallax method can be used to measure the distance to stars up to 400 light years away. I did a quick calculation and estimated that it means that our telescopes can resolve an angular movement of 8.15x10-3 arc seconds. Taking the distance between the sun and the...
  44. ASmartDude

    B Is there a specific unit used to measure redshift?

    i have been learning about using redshift to measure the distance of far-flung objects, but in all my research i never saw a specific unit used to quantify how redshifted an object is. to me it seems like an oversight, because such a unit would be very useful for the study of distant galaxies...
  45. A

    How can I measure the force applied to something?

    Homework Statement For a personal project I am doing, I want to test a range of forces in the horizontal direction, and see how the device I created reacts at different forces. So for example, if I want to apply 5N specifically to a device, to see how it reacts under that force, how would I go...
  46. DariusP

    How did H.K. Onnes measure temperature and resistivity?

    How did H.K.Onnes measure temperature and resistivity? As you know, Onnes is a dutch physicist that was the first person to liquefy helium and discover superconductivity a year or so later. I am wondering - what equipment was he using at that time? I couldn't find this information anywhere...
  47. D

    Measuring the Force Required to Separate Two Magnets at a Distance

    Hi, i have a question. I need to know how much Newton it takes to separate 2 magnets or a magnet from a from a piece of metal. I've bought a spring scale that measures max 50 gram, so very accurate. Now what if i attach the scale to the magnet and i pull it horizontally just enough to...
  48. M

    MHB Degree Measure of Central Angle

    In a circle of radius 3 meters, the area of a certain sector is 20 m^2. Find the degree measure of the central angle. Round the answer to two decimal places. Must I use A = (1/2)(r^2)(theta)?
  49. neilparker62

    Measure ionization energy (Hydrogen/Deuterium)

    Just wondering if there's any accurate method for direct measurement of the ionization energy of atomic Hydrogen and/or Deuterium ? There's lots of measurements on transitions between various hydrogen/deuterium energy levels but not (it seems) to the limit where n = infinity. Alternatively...
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