Measuring Definition and 962 Threads

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...

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...

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...

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...

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...

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...

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...

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...

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.

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!

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

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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

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...

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...

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

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...

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...

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...

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...

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..?

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...

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...

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...

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...

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

When mixing special grades of alloys, or even in commercial production of common alloys, furnaces are often used where metals or additives are added and mixed, then samples taken at the core and characterized, then adjustments are made by adding additives until the desired composition is...

Greetings, PF'ers I've got a project where I'm trying to measure the distance from a stationary AM radio beacon transmitting a short coded pulse every 300ms or so to a non-stationary receiver. I'm dealing with a range of about 1 to 500 ft between points. I need to have at least 1'' accuracy...

Hi! My name is Daniel and I'm new to this forum. I work as a mechanical engineer at a machining workshop in Norway. We are currently producing some steel shafts that require a high level of accuracy. The shafts are about 1500mm long, and has a diameter of 40mm h6 (+0,000mm, -0,011mm) all...

Homework Statement This is more to do with an experiment I'm failing terribly at rather than a direct homework question. I could not find the right section to ask this in. Investigate the inductance of inductors with cores of Perspex and Copper using an Anderson's bridge. For Perspex, compare...

Does everything give off some sort of radiation? Example: water, oil, mud, etc. If so, how can it be measured? Is there a way to translate a radio wave into a frequency in the visible spectrum and see it bounce off a wall?

I'm trying to measure the coefficient of friction between a wheel that weighs about 4 grams and a ping pong table. Are there accurate spring scales I can use to measure the force it takes to move the wheel? I'm estimate the force required to move the wheel to be in the thousands POUNDS (.00xlb)

Homework Statement Why would it be important to have the resistance high when measuring voltage and the resistance low when measuring current? Homework Equations The Attempt at a Solution

I am doing a senior design project regarding water hydration and did some tests to get a general evaporation rate. I assumed that evaporation is proportional to the surface area of the water to air boundary so I thought that the water level of water in any constant cross section container should...

I am reading a paper from Yakir Aharonov and others revisiting Hardy's paradox and I have a question. Let me state the notation first as brief as possible so that we can use it in the discussion: * a positron e+ goes through either the overlapping arm o+ or the non overlapping arm no+ of a...

Homework Statement A Pitot-static probe connected to a water manometer is used to measure the velocity of air. If the deflection (the vertical distance between the fluid levels in the two arms) is 7.3 cm, determine the air velocity. Take the density of air to be 1.25 kg/m3. Homework...