What is Measuring: Definition and 1000 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. D

    Measuring current in RLC circuit

    Homework Statement I've recently completed a experiment involving a Driven series RLC circuit. The potential difference across R " a variable resistor >> internal resistance of inductor" was measured. When calculating the current from the PD across R, should I include the internal resistance...
  2. H

    Measuring eddy currens in a pipe.

    I need a simple method to measure eddy currents in a pipe. Thanks.
  3. DocZaius

    Understanding the Probability of Measuring an Allowed Energy in a Wave Function

    In Griffiths' page 36/37 he says "As we'll see in Chapter 3, what |Cn|^2 tells you is the probability that a measurement of the energy would yield the value En (a competent measurement will always return one of the "allowed" values - hence the name - and |Cn|^2 is the probability of getting the...
  4. U

    Measuring obstacle size in a parallel circuit of different lengths of wire

    Homework Statement In lab, we were instructed to create a circuit that uses nichrome wires and identical bulbs to measure the obstacle caused by an object. To do this, we slid the alligator clip along the nichrome wire until the 2 bulbs in parallel are the same brightness. The object that we...
  5. L

    Distance Measuring Sensor Advice

    Hi There, I'm looking for ideas on finding the position of objects (such as a hand or foot) placed in a tank. Without using a camera soultion, I think the use of something like a minature laser range finder or IR proximity sensor. My problem is that I need to find distances between 5cm (min...
  6. H

    Measuring energy and then momentum

    Hi there, Im confused by something that came up in my quantum mechanics lecture. The lecturer posed us a question. What result do I get for a measurement of momentum if I have already measured the energy. I assumed after measuring energy that the system would be left in an energy...
  7. A

    Vectors as Paths with measuring degrees

    Homework Statement A hiker's trip consists of three segments. Path A is 6.0 km long heading 60.0° north of east. Path B is 6.0 km long in a direction due east. Path C is 4.0 km long heading 315° counterclockwise from east. (a) Graphically add the hiker's displacements in the order A, B, C...
  8. D

    Determining Heat of Combustion for a Fuel and Oxygen Mixture

    Homework Statement n A student performs a combustion experiment by burn- ing a mixture of fuel and oxygen in a constant-volume metal can surrounded by a water bath. During the experiment, the temperature of the water is observed to rise. Regard the mixture of fuel and oxygen as the system...
  9. S

    Measuring Slipperiness of Fluids on Inclined Planes

    I want to test several different fluids on an inclined planes and figure out which one is the most slippery. What would be the most scientifically sound way to measure this?
  10. I

    Camera projection errors measuring length

    So here's the situation, say i record, presuming the camera is perfectly vertical, an object falling next to a ruler. I then find how many pixels that ruler is and from there i can translate how many pixels the object has moved into how far the object has moved. The question is how reliable is...
  11. M

    Engineering Print a circuit for measuring electrical impedance

    Hi there, I am supposed to measure the electrical impedance (which depends on conductivity) of an electrically conducting object by use of eddy current technique induced by an air core coil. for this purpose I need to print a circuit. would you please help me with the characteristics and out...
  12. C

    Measuring distance with parallax

    Homework Statement a) Two observers are separated by a baseline equal to Earth's diameter. If the differences in their measurements of Mars' position at opposition (i think this means when it is closest to earth) is 33.6" (arcsec). What is the distance between Earth and Mars at opposition...
  13. C

    Measuring of electrode potential.

    In set-up with two half-cells and a voltmeter, the potential difference is measured using the voltmeter. But voltmeter has high resistance,which i know is still able to measure potential difference,but wouldn't it prevent electrons from flowing What i meant was,the use of voltmeter creates a...
  14. G

    Measuring the size of the observable universe

    The size of the observable universe usually gets put at 93 trillion light years, though some people believe it is infinite, though I'm not sure which camp is in the majority. Those who believe it is 93 trillion light years across are they just assuming that the size of the universe at the first...
  15. Vorde

    What is this plastic measuring thing?

    http://postimage.org/image/urnvnzkhz/ I was watching a tv show (the astute watcher will recognize it as How I Met Your Mother), when I saw one of the characters holding this thing (the curved plastic measuring-thing). My dad used to have one of those on his work bench, and I used to play...
  16. M

    Simultaneously Measuring Entangled Particles

    Let's say you have entangled particles emitted from a source. What happens if you measure the spin of both entangled particles simultaneously with respect to the reference frame of the source? Would the spins measured still be opposite (anti-correlated)? Would you even get a definite...
  17. G

    Measuring error analysis with 3 variables

    Homework Statement Consider the function F(xyz)=x^4+5y^4+2yz+3. Let the uncertainty in x be represented by the variable dx, the uncertainty in y be represented by the variable dy, and the uncertainty in z be represented by the variable dz. Find an algebraic expression for the uncertainty in...
  18. S

    Multimeter current level when measuring resistance

    Hi, When using a multimeter to measure resistance, what is the used current level of the multimeter? I am using Fluke 77 IV Series Digital Multimeter. Thanks.
  19. S

    How Can I Measure the Impact Protection of Running Shoes?

    Can anyone recommend a device or way I can measure the impact protection qualities of different running shoes? I am a runner and would be interested in doing this myself. I appreciate it!
  20. M

    Measuring RMS Voltage with a DMM

    Suppose at a test point in my circuit ,I need to measure rms voltage, how I should measure it with DMM?
  21. F

    Measuring SI Units on a Desert Island

    A few years ago, I was reading about a contest open to everyone. The question was something like : if you were on a desert island, with unlimited natural resources, and access to a book with the most accurate values of properties for various natural things (i.e. gravitational acceleration on...
  22. M

    Measuring voltage between your fingers

    If I hold one lead of my multimeter to my left index finger, and the other lead to the right index finger, it gives a reading of around 30mV. The reading quickly drops when I leave it there. I tried measuring the voltage between myself and the ground and it read 0mV. Whats stranger is that if I...
  23. G

    Measuring the Richter Scale with logarithms

    An Earthquake measures 6.1 on the Richter Scale. What is the rating on an earthquake that is twice as powerful? I = I0 × 10M I-intensity of earthquake I0-earthquake with intensity of 0 M-magnitude of earthquake on the Richter Scale So I figured I'd use I1 = I0 × 106.1 to find the...
  24. S

    Measuring the pressure of a gas

    http://img526.imageshack.us/img526/8780/pressurew.jpg I worked out that the pressure difference is 1000 pascals For part b the book says the pressure of the gas is 1000 pascals but shouldn't it be 1000 pascals + 100,000 pascals (atmospheric pressure) making the pressure of the gas 101,000...
  25. C

    Measuring resistance in a superconductor

    I am currently an intern at a superconductor lab and have been faced with a personal curiosity. I work with a device that determines the critical temperature at which the material stops superconducting. This device is composed of an electric temperature probe and two coils of wire which are...
  26. T

    Question About Measuring Specific Heat Capacity

    Recently, I did a physics lab experiment to find the specific heat capacity of an unknown sample material. The lab instructions kept insisting that the sample had to be kept in boiling water for at least 10 minutes. My question is why? Could I have found the specific heat capacity if the sample...
  27. S

    Tool for measuring inner dimensions of a tube from an offset position

    Hi, I'm trying to measure how far a rod that passes through a tube is offset from the center. Assume that the axis of the tube runs parallel to that of the rod. I can only access the interior of the tube from above (it hangs vertically), and the access hole I have is smaller than the radius...
  28. R

    Measuring SoC/life on Li-ion battery - help please

    Hi all, I've been trying to find some sort of multimeter/voltmeter/etc that will allow me to get an accurate (and independent of the handset) read on state of charge, or remaining life, on a standard cell phone li-ion battery. I've found a few voltmeters and the like, but my understanding...
  29. M

    Measuring surface tension of a bubbles.

    Homework Statement The pressure by the walls of a bubble is 4σ/r (where σ is the surface tension). The radius r of 2 bubbles is measured. After that you bring the two together by connecting them with a straw (the smaller bubble has higher pressure and gets smaller, while the bigger bubble...
  30. T

    Measuring Observables in 3+1 Formalism

    Hello, lets say I have Hamiltonian aproximation H(\vec{x}_a,\vec{p}_a) of gravitational interaction that can be used for n-body simulation of mass particles and photons. Spacetime curved by simulated particles would be asymptoticly flat. But I don't have a metric etc. All I have is evolution...
  31. F

    HUP and the effects of measuring a particle

    If I want to measure the position of a particle, and to do so I bombard it with a photon. What attributes of the particle will this interaction affect? I would think that it could affect both the particle's direction and its mass, which in turn would have an effect on both its position and its...
  32. S

    How to get components of Riemann by measuring geodesic deviation?

    Hi all, I'm now reading Chap 11 of Gravitation by Wheeler, etc. In exercise 11.7, by introducing Jacobi curvature tensor, which contains exactly the same information content as Riemann curvature tensor, we are asked to show that we can actually measure ALL components of Jacobi curvature tensor...
  33. M

    Experimentally measuring torque.

    What experimental methods are there for measuring the static (and dynamic if possible) torque required to turn a simple tooth gear? This tooth gear is used to rotate 4 wheels, 2 of which are connected to the shaft and 2 are on another shaft with the two shaftes connected with a toothed belt to...
  34. U

    Measuring Current Noise Density

    I have a power source that is supposed to be low noise, and i want to verify that the data the company sent me is indeed accurate. In order to do this, i want to reproduce their graph showing current noise density (nA/root(Hz)) on the Y axis, and Hz on the X axis. I am an undergraduate physics...
  35. coktail

    Measuring the speed of light at different velocities

    Let's say there is a football field with a mirror set up in one of the end zones. If I am standing at the 50 yard line with a laser, and I point it at the mirror (facing me) in the end zone and shoot of a single blast of the laser and then record it's velocity as it bounces back and hits a...
  36. Drakkith

    Measuring Radial Velocity with Amateur Equipment

    Would it be possible to measure the radial velocity of stars with large exoplanets using amateur equipment?
  37. E

    What is the pendulum period on a moving vehicle at 0.6c compared to Earth?

    I have been trying to come up with a solution for the matter but I failed, so here are my questions. I would appreciate if someone explained thoroughly. a) There is a pendulum which has a period of 20 seconds on Earth. If it was put on a vehicle moving at 0,6c and have its period measured...
  38. Drakkith

    Measuring the Speed of Light at Relativistic Velocities

    Let's say you have a spaceship with an observer on it who has an experiment set up on the ship to measure the speed of light from a laser beam that is directed at the ship from behind. This experiment consists of two mirrors, one half silvered to only reflect part of the beam, that reflect the...
  39. C

    Measuring the sound of fireworks.

    Homework Statement A firework charge is detonated many metres above the ground. At a distance of d1 = 590 m from the explosion, the acoustic pressure reaches a maximum of ΔPmax = 10 Pa (see figure below). Assume the speed of sound is constant at 343 m/s throughout the atmosphere over the...
  40. R

    Measuring volume of spheres using triple integrals

    Homework Statement I'm just interested in knowing where the 4 comes from in front of the integral.
  41. A

    Red/Blue Shift for measuring absolute velocity

    Would it be possible to stand at a point, surrounded by sensors and fire beam of light of at specific frequency at every sensor and determine our absolute velocity without a reference based on the amount of red/blue shift detected in the frequency of each beam? Wouldn't light observed by the...
  42. K

    What Happens When Measuring Lz on a Non-Eigenstate Wavefunction?

    Homework Statement I have a wavefunction ψ(r), I want to know what the probability of obtaining a specific value, say 0, Is upon measuring the z-component of the angular momentum Lz What do i do? The Attempt at a Solution My first thought is to apply the Lz-operator to my function and see...
  43. V

    Measuring water pressure in an open tank

    Hello to everyone... I've been reading these blog and searching the web trying to find a solution for my problem, but I couldn't find anything. I need to meassure the water pressure (differential pressure) in an open tank. The colum of water is aprox. 10-15cm tall. I need to do these...
  44. D

    Measuring pressure across a centrifugal pump

    This should be an easy one but here goes... I am trying to easily measure flow rate in a pipe which has an in line centrifugal pump (Grundfos UPS 25-60) creating the head in the system. I have been told that installing a pressure gauge before and directly after the pump will give me system...
  45. S

    Measuring linear velocity of a toy car

    I want to measure the linear velocity of a toy car.. i had a thought over it.. i m thinking of using a optical mouse to do so , i need to process the usb output , how shud i do it ?.. and can there be any other cheap way of doing it..?
  46. P

    Measuring distances between a moving object and a stationary object using light

    Hi there When measuring the distance between 2 objects, say, the Earth and a spacecraft traveling very close to the speed of light. If I used a laser and a mirror to bounce a light beam between the 2 objects, I would take the time the light took to return to me, multiplied by the speed of...
  47. C

    Question about measuring physcial observables

    So my measurement of a quantum system is an eigenvalue of that operator. And we are not able to predict what eigenvalue we will get, even if we knew the precise state vector before we make our measurement. But QM allows us to calculate the average of all these eigenvalues, if we made an...
  48. M

    Measuring intensity of superposed waves using complex amplitudes

    Hi, Suppose we have the x and y components of the electric field being described as (E_{x}e^{i(kz-\omega t)}, E_{y}e^{i(kz-\omega t +\phi)}), what is the intensity? I think the correct answer is E_{x}^{2} +E_{y}^{2} + 2E_{x}E_{y}\cos\phi. However, I am not sure how to deal with this using the...
  49. R

    Measuring force in rain gauge.

    Homework Statement The .png file attached shows a simple rain gauge where rain water is collected through a funnel of 25cm diameter. As water flows through the sides of the vessel and it fills the vessel it exerts an upward force on the bottom surface of the float. This force is transmitted...
  50. M

    Measuring up to ~2T magnetic fields

    What do you propose as a quick DIY method for measuring magnetic field flux densities around ~2T?
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