What is Measurements: Definition and 394 Discussions

Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. The scope and application of measurement are dependent on the context and discipline. In natural sciences and engineering, measurements do not apply to nominal properties of objects or events, which is consistent with the guidelines of the International vocabulary of metrology published by the International Bureau of Weights and Measures. However, in other fields such as statistics as well as the social and behavioural sciences, measurements can have multiple levels, which would include nominal, ordinal, interval and ratio scales.Measurement is a cornerstone of trade, science, technology and quantitative research in many disciplines. Historically, many measurement systems existed for the varied fields of human existence to facilitate comparisons in these fields. Often these were achieved by local agreements between trading partners or collaborators. Since the 18th century, developments progressed towards unifying, widely accepted standards that resulted in the modern International System of Units (SI). This system reduces all physical measurements to a mathematical combination of seven base units. The science of measurement is pursued in the field of metrology.

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  1. S

    Two measurements. Different trust.

    Dear all, I have two methods to determine a value. Method one, gives me value A with uncertainty sA, and method 2 gives me value B with uncertainty sB. The distance between the values is larger than the addition of their respective uncertainties. Here is my problem. If I believed both numbers...
  2. J

    PH measurements and applications

    Homework Statement A solid acid is dissolved in enough water to make 200 mL of a solution. 40.0 mL of the solution is titrated to a phenolphtalein end point with an NaOH solution. The neutralized solution and the remainder of the acid solution are then mixed and the pH of the resulting...
  3. H

    Calculate Parameters of Shifted Exponential Density from Measurements

    I have a density function: f(t) = L * e-L(t-t0) * u(t-t0) where u(t) is the unit step function. And I have a column vector X, which is randomly chosen samples from f(t): X = [x1 x2 ... xn]T How can I estimate the unknown values t0 and L from this X vector?
  4. A

    Surface Tension Measurements with the program SCA20

    I start working with the OCA15plus tensiometer and I don't know what the three red lines that appear in the program SCA20 means and how should I position them in the image of the drop on an analysis of surface tension by pendant drop method, for example. Can anyone help me?
  5. M

    Measurements between sun and earth

    Hi everyone my name is Fabien I was wondering is there any accurate way to measure the distance between the Earth and the sun without having some professional materiel. IF yes How accurate are we talking about? How do you do if you want to know precisely? How do the scientist do it? Do you...
  6. C

    Calculating the overall uncertainty of my measurements

    Homework Statement I conducted an experiment to find the refractive index of several concentrations of sugar solutions. I now need to find out the final uncertainty of my measurements but am unsure of how to go about calculating it. Homework Equations I took 2 measurements of length which...
  7. L

    Two measurements on one electron at nearly the sametime but different place

    Hi,all. My problem is: viewed theoretically. The probability of finding an electron is none zero in everywhere. experiments: observer1 found the electron in positionA at t=0, observer2 is at positionB which is L (distance) away from positionA, then at t<L/c, observer2 opens his microscope...
  8. L

    What is the best way to combine uncertainties in measurements?

    Homework Statement Suppose I have N x_{i} measures with a given uncertainty \Delta x_{i}. I want to have the best estimate for \bar{x} and its uncertainty \bar{\Delta x} 2. Homework Equations /3. The Attempt at a Solution Well, I'm not exactly sure because or I can have a mean...
  9. LarryS

    Double Slit Experiment and Measurements

    When a photon encounters a beam splitter, say a half-silvered mirror, there is a 50-50 chance it will be reflected or passed (tunneling). Does being reflected/passed constitute a QM "measurement"? Thanks in advance.
  10. T

    Confusing Old time Measurements =(

    Homework Statement A furlong is and old British unit of length equal to 0.125 mi, derived from the length of a furrow in an acre of plowed land. A fortnight is a unit of time corresponding to two weeks, or 14 days and nights. Find the speed of light in megafurlongs per fortnight. (one...
  11. B

    Finding component weight and angle measurements

    Now I know you can't outright give me the answer to this question but some useful tips would be appreciated as this is my first time taking physics. Thank you. A boulder of weight w rests on a hillside that rises at a constant angle x above the horizontal. Its weight is a force on the...
  12. J

    Measurements with an Ammeter/Voltmeter

    Homework Statement 1) What is needed for an ammeter to measure current accurately? 2) What is needed for a voltmeter to measure the potential differences in the circuit accurately? 3) How can you construct an ammeter from a resistor and a galvanometer? 4) How can you construct a voltmeter...
  13. D

    Weak Measurements and Determinism

    Just a thought: If we could identify the position and velocity (via weak measurements) of a particle at some instant, and its future evolution is fully determined (at least in principle, not in practice), then can we extrapolate this to surmise that all events are are inherently deterministic...
  14. K

    Dynamic hardness measurements

    hello. can anyone help me find information about "dynamic hardness measurements" ? a direction to books or websites will be very helpful... thanks
  15. G

    Power Measurements: G, R, K for KW & MWh

    I am a little confused on the difference between statements of electrical output when the talk of gigawatts or gigawatt hours? for the formula P=ghrk where P is power in kilowatts g is gravity (9.8) constant r is flow of say water per second k is efficiency...
  16. G

    Error in Measurements: Confused?

    This has been very comfusing. Is the error in taking a reading the smallest or half the smallest division? Say a standard 30cm ruler, you can judge to nearest 0.5mm but since you take 2 readings you need to double the error. But then in titrations using a lab burette you count the titre as half...
  17. B

    Multisim and Actual measurements inconclusive

    hello all, i am a beginner student in this field at NHTI in concord NH , the problem i am having is that my multisim program measurements for a simple voltage point at a resistor is inconsistent with the actual measurement that i got in the lab...? why is this? is my math wrong? here i will give...
  18. K

    Another confusion: How many measurements is many ?

    Another confusion: How many measurements is "many"? Since quantum mechanics gives only statistical prediction, we actually need numerous measurements to verify the theory. But how many measurements will make it statistically meaningful? Let's say we want to verify the uncertainty principle, we...
  19. K

    Statistical Analysis Question: How many measurements to reduce uncertainty?

    Homework Statement a. Mike makes six independent measurements of the diameter D of a leap year detector that made its way into the lab, obtaining D = 4.64, 4.78, 4.82, 4.68, 4.80, and 4.95m. What would result would he report in a lab writeup? b. Alice does the same experiment as Mike, but...
  20. H

    Can anybody let me know in detail about time and its measurements.

    Can anybody let me know in detail about time and its measurements.
  21. U

    Calculating the Relative Error & Improving Accuracy of Measurements

    Hi Can anyone help me to solve the following question; Note: in both equations the +/- is written above and below of each other without the '/' sign. Thanks.
  22. J

    Amateur radio + frequency measurements

    For an exam I am studying for, I have to understand the effect of measurement tolerance, calibration accuracy and time-related drift on frequency measurements. Im aware that the time-related drift is due to the oscillator frequency becoming less accurate (due to continuous crystal vibration)...
  23. J

    Quantum Measurements and Macroscopic Objects

    In the beginning there were only probabilities. The universe could only come into existence if someone observed it. It does not matter that the observers turned up several billion years later. The universe exists because we are aware of it. — Martin Rees Professor of Cosmology and...
  24. G

    Quantum Mechanics - Measurements and Observables

    Homework Statement Consider a state |psi>, and two non-commuting observables A and B. Now study the following chain of measurements: (i) On |psi> a A [sic] measurement gives the result a1, and a subsequent measurement of B gives the result b2. (ii) On |psi> a B measurement gives the result...
  25. Peter Morgan

    Wanted: quotes that encourage thinking of experiments instead of measurements

    The classic reference on this is Bell's (highly recommended) polemic "Against measurement", which is in the 2nd edition of Speakable and unspeakable in quantum mechanics (but not in the 1st edition; it can also be can be found in the original, Physics World 3 (August 1990), page 33). A quote to...
  26. W

    Absolute velocity measurements

    Hi all, this is my first post to the forum. I've been thinking about a mechanism that can't work, but I can't figure out why not. Here is the idea: 1) If I have two wires parallel to each other on a table and I run a current through them, they will be attracted to each other. I believe...
  27. D

    Exploring the Effects of Space Motion on Light Measurements

    In this example I make 2 assumptions 1. if an object is moving through space at time T0 it will be at point x,y,z,T0 and at a different time T1 it will be at a different position x,y,z,T1. The other assumption I make is that light is non ballistic. see the associated pics Referring...
  28. jambaugh

    Measurements and The Copenhagen Interpretation

    I started this thread to continue the following discussion from the thread: https://www.physicsforums.com/showthread.php?p=2203566#post2203566" But you and Weinberg are both making a mistake in assuming ontological status to both the collapse of the wave function and to entanglement...
  29. J

    Error in bandgap measurements of n-type Ge

    In conducting an experiment to measure the bandgap of n-type Ge using the 4-probe method, heating the sample and measuring the change in voltage across the probes as it cooled, it was necessary to change regularly between the milliammeter and the millivoltmeter setting on the instrument to...
  30. P

    What forces are used in AFM measurements?

    I am asked 'name 3 example of interactions that can be measured by AFM techniques', then followed by 'name 3 examples of the types of interaction forces that are measured with AFM'. 1) Aren't interactions kinda the same as interaction forces? 2) I thought there is only one force, van de...
  31. S

    Calculating Pressure Change Due to Immersion in Water

    Homework Statement The spring of a pressure gauge has a force constant of 1250 N/m, and the piston has a radius of 1.20 cm. As the gauge is lowered into water, what change in depth causes the piston to move in by 0.750 cm? Homework Equations F = -k\Deltax \frac{F}{A} = Y\frac{\Delta...
  32. S

    Least Square Fit of Multiple Measurements with Shared Parameters

    Dear All, I would like to least square fit a number of measurements using several nonlinear functions with shared parameters (similar to the advanced fitting in Origin) using Mathematica. Therefor I would be interested in an Algorithm like Gauss-Newton that fits several data-set to several...
  33. N

    Simple Question: Measurements of length & mass ZZZ

    Discuss the effects of the following sources of errors on Measurements of length & mass. and suggest metods to overcome them: 1- Existing of a dust on both the sample and the measuring devices. 2- Irregularity of the samples. 3- Slope of the balance from the horizontal line. 4- Other...
  34. K

    Probability of simultaneous measurements of momentum and position

    Query: Given a three- dimensional wavefunction (phi) (x, y, z), what is the probability of simultaneously measuring momentum and position to obtain the results a < y < b and p' < Pz < P" ? I know that integration of the square norm of the wavefunction of the region under question...
  35. S

    Finding Observable Values from Hermitian Measurement Operators

    Homework Statement OK, so assuming we have a physical observable with three values, a(1),a(2) and a(3), and there are given matrices for the measurement operators M(a(1))...M(a(3)). How does one actually go about finding a(1),a(2) and a(3) given the matrices?The Attempt at a Solution These...
  36. wolram

    Measurements of the WIMPonium state

    arXiv:0901.2125 (cross-list from hep-ph) [pdf, other] Title: WIMPonium Authors: William Shepherd, Tim M.P. Tait, Gabrijela Zaharijas Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena...
  37. M

    Light waves through grating. Min and Max measurements of wavelenghts in nm

    Homework Statement Light passes through a 220 lines/mm grating and is observed on a 1.4m wide screen located 1.2m behind the grating. Three bright fringes are seen on both sides of the central maximum. What are the minimum and maximum possible values of the wavelength? Express your answers in...
  38. A

    Looking for a wireless system for collecting 12+ temp. measurements

    I was wondering if anyone has suggestions in terms of wireless transmitters/receivers for a system that will have over a dozen temperature measurements (either thermocouples or RTD's). I have no idea where to even begin looking. Thanks,
  39. S

    Print ViewSimultaneous Measurements of Position and Velocity

    Homework Statement The x coordinate of an electron is measured with an uncertainty of 0.200 mm. What is v_x, the x component of the electron's velocity, if the minimum percentage uncertainty in a simultaneous measurement of v_x is 1.00 %? Use the following expression for the uncertainty...
  40. A

    How to work out the uncertainty of some measurements?

    Homework Statement i am trying to work out the uncertainty of some measurements but i don't know how to, i tried finding some info on it online but i cant, well these are my 10 measurements 9.13mm 9.12mm 9.13mm 9.12mm 9.12mm 9.13mm 9.13mm 9.12mm 9.13mm 9.12mm Homework...
  41. B

    How Does an Accelerating Observer Measure Light Velocity?

    Will an accelerating observer obtain the same value for light velocity as one at rest or moving at constant velocity? Will the measurement be the same for linear and radial (circular motion) acceleration?
  42. D

    Repeated Measurements Homework: True or False?

    Homework Statement This is a true or false question on a practice test. I'm having a hard time making sense of it. Here it is: Two operators A and B do not share eigen states a(n) and b(n) where n=1,2,3,etc. A measurement of A is made and the system is found to be in state a(1). If the...
  43. N

    QM: Changing wavefunctions after measurements

    Homework Statement Hi all. My question is best illustrated with an example. Please, take a look: Let's say we have particle in a stationary state, so \Psi(x,0)=1\cdot \psi_{1,0}(x) with energy E_{1,0}. Now at time t=0 the Hamiltonian of this particle changes, since the particle gains some...
  44. S

    Volume Measurements: Questions, Errors, Limitations

    Please, please look at the document I've attatched. My questions are: Have I done the calculations correct? Do I have correct significant figures? I have to discuss the random and systematic errors... but I don't know what ones that we've had. Help? And they tell us to point out...
  45. J

    Width measurements and conversions

    Homework Statement a. How wide is the gap between tiles in centimeters? b. How wide is the gap in inches c. How many algae-thicknesses is the gap between tiles Homework Equations The Attempt at a Solution First off, I just want to know if I did a and b correctly. To set up...
  46. M

    Accuracy of Current and Voltage Measurements

    In general, are the measurements of current or voltage more accurate? From our lab experiments, it seems that voltage is more accurate. I'm curious as to why this is the case. My guess is that because current itself is the measurement of the flow of the electric charges it would be more...
  47. C

    Measurements of the Speed of Light

    Homework Statement The Apollo 11 astronauts set up a highly reflecting panel on the Moon's surface. The speed of light can be found by measuring the time it takes a laser beam to travel from Earth, reflect from the retroreflector, and return to Earth. If this interval is measured to be 2.51...
  48. D

    Light, Vacuum, Speed, and Measurements

    They say often that light only travels at light speed in a vacuum. That it slows down in air and water. I do not think this is true - correct me if I am wrong as I usualy am :shy: All atoms are vacuum. Light is energy that is not made of atoms, or in other words it is smaller then atoms if...
  49. S

    Charge carrier concentration measurements in working electrode

    Dear All I will be grateful for any idea on how to measure electrochemically the charge carrier in an electrode say working electrode made of Al. Thank you from advance Shay
  50. N

    Is Strong Nuclear Force Measured Using F=p*E/hbar Equation?

    How is strong nuclear force measured?
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