Ground Definition and 921 Threads

hi i just want to ask about the formula of Doppler Effect . The speeds of the listener VL and the source Vs are relative to the ground, source, or listener ?

I'm having a difficult time understanding precisely how alternating current works in relationship to ground (earth). I have spent hours trying to learn online and I get conflicting explanations. So let's start with a power plant. A coil of wire is rotated in between magnets, inducing a...

Homework Statement A 15 kg block slides along a horizontal frictionless surface 3.0 m above the ground at a constant speed of 2.0 m/s. The block then slides down an incline that makes an angle of 35° with the horizontal and has a coefficient of kinetic friction equal to 0.30. After reaching...

Homework Statement The question is to find the total angular momentum of the following atoms in their ground state - Na (11 electrons), and Rb (37 electrons). That's all the info given. Homework Equations I have no idea - that's what I can't find! The Attempt at a Solution I've...

I am looking to find the reaction forces on the bottom of the rectangular shape I have included (sorry for the crude diagram). I have a moment on the top right beam (390600 lb/in) and a distributed load of 160 lb/in across the entire surface of the top of the rectangular prism. I am looking...

This a question from projectile motion. This is NOT "homework"; it's a concept that got me thinking. When a projectile is launched from the ground level and it falls back on the same (ground) level, the horizontal displacement is maximised if the angle of projection (with respect to the...

I'm making a small capacitor for a project at uni, where I'll be encasing the whole thing in a metal box for shielding, which needs to be grounded. However, I don't know how to actually go about doing this? The device will be indoors, so I can't just throw a steak in the ground. Any advice is...

Homework Statement If I throw a rock upwards with an initial velocity and throw a rock downwards, what is the speed of the rocks just before they hit the ground? Homework Equations The Attempt at a Solution\ They should hit the ground at the same speed and different times. I...

It is the procedure you do to get ground term symbol in LS coupling. What is meant by this "ground term"? As in a physical meaning. If you don't know the procedure it is in this link: http://en.m.wikipedia.org/wiki/Term_symbol, please seek "Ground State Term Symbol" Section.

As I understand it, if Hubble was turned on the Earth in a geo-stationary orbit it would struggle to pick out a couple of tanks on the ground. So how large would a telescopic satellite need to be (geo-stationary) to pick out a nickel on the ground? Is it even technically possible? I gather...

Is there an experimental verification of the radial probability density for the hydrogen ground state given in the introductory texts. See the following link as an example. Thank you in advance. http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hydrng.html#c1

Homework Statement Calculate the expectation value for a harmonic oscillator in the ground state when operated on by the operator: $$AAAA\dagger A\dagger - AA\dagger A A\dagger + A\dagger A A A\dagger)$$ Homework Equations $$AA\dagger - A\dagger A = 1$$ I also know that an unequal number of...

I realize that at ground state of a harmonic oscillator the energy will be at zero. I'm assuming that the expectation value will also be at zero. Could someone confirm this & possibly explain just a little more. Thank you

Why the ground state HOMO level of a molecule with two opposite-spin electrons, is singlet while we know that a level with two opposite-spin electrons may be singlet(s=0,m=0) or triplet(s=1,m=0)?

Can somebody clear the fog in front of my eyes: how can a Hamiltonian describing free fermions have a ground state with non-trivial entanglement? My reasoning is: we can build the ground state in the independent electron approximation (which is now exact), hence it is a product state in the...

Homework Statement Homework Equations The Attempt at a Solution The ground is at zero potential. Hence, the sphere should be also at zero potential. The net charge should be zero, so a charge of -Q should flow from the ground to sphere. But this is wrong. :confused:

Well, I took my Physics final today, and I passed it but I didn't do quite as well as I'd hoped. Anyway, there was one problem I spent tons of time trying to figure out. I've tried giving it a shot again at home, but it's still eluding me. Some guidance would be great! Sorry if this is...

Is there any current flows from point A to the ground (see the attachment)? We use ground node to idicate somewhere in the circuit has ZERO electrical potential. Do we really connect that point to the ground in real world or we just mark that point to make it easier to do calculations?

A chimney is demolished by breaking its base in hope that when it falls the top of the chimney will prescribe a circle. If the chimney is broken into two segments in the air, will the top segment reach the ground first? I have attached my professor's solution. My professor didnt...

Hello everyone, Can you guys please explain why a potentiometer needs a ground (-) wire? or what does it do differently and what uses there are for it as opposed to a rheostat. Recently been playing around with automotive sensors like the TPS (Throttle Position Sensor) on a car and just...

I was instructed to display an AC signal on an oscilloscope with "ground at zero." Does anyone know what ground at zero is? The signal is basically a sine wave, BUT with the bottom cut off (when the sine wave is supposed to be negative, it is 0 instead).

Hello PF members, I am trying to solve for helium atom ground state by using perturbation theory. It is very easy to calculate the first order correction of ground state energy but I have no idea for how to find its wave function. I have tried to use the first order correction formula for wave...

Hi forum! So I was trying to learn how to use PIC In the tutorial,they said I should add a bypass capacitor between power supply and ground. But will the whole thing shorted out because of this connection?Why or why not?

for the 1st two I used v is to the reference frame = 37m/s- -35m/s=72m/s a)ball=[(m2-m1)/(m1+m2)]v bat=v2=[(2m1)/(m1+m2)]*v b) I do not know how to solve for part b. The Attempt at a Solution

For example if a hat is lined with nickel, silver, EMF paint, etc. , then how do you ensure the hat is grounded? I am a little unsure what grounding means relating to these forms of usage as I have seen EMF protective clothing advertised as grounded.By EMF I mean sufficient for all freq with...

Homework Statement (Assume no friction) A car that has a mass of 3970 kg is accelerated from an initial velocity of 0 up a ramp that is 50 meters long (the hypotenuse) and has a height above the ground at the end of the ramp of 10 meters. The velocity of the car at the end of the ramp is 150...

Is there some mathematical prove that for ground state in QM problems wave function doesn't have any zeros?

Hello Everybody, In page 86, in Peskin & Schroeders Introduction to QFT, the following expression is introduced to analyze \left | \Omega \right >; the ground state of the interacting theory: e^{-iHT} \left | 0 \right >. Where |0> is the ground state of the free theory and H is the...

Homework Statement helicopter, traveling horizontally, is 82 m above the ground. The pilot prepares to release a relief package intended to land on the ground 96 m horizontally ahead. Air resistance is negligible. The pilot does not throw the package, but let's it drop. What is the...

in household supply, one wire is neutral wire and another is ground. Both are at 0 potential. My question is that can we interchange both wire. I mean use live wire with ground?

Was reading a crane-operations manual and it had a Section on what to do if your boom accidentally contacted overhead electrical wires. It advised not trying to step out of the cab (of course); but in case of imminent danger advised jumping out (makes sense). The interesting part came after...

Homework Statement Why does <0|\frac{1}{(2\pi)^3}∫ \hat{a}^{\dagger}(t,r) \hat{a}(t,r) d^{3} \textbf{k} |0> = \frac{1}{\pi^2}∫|β|^2 k^2 dk. Where \hat{a} and \hat{a}^{\dagger} and its conjugate are bogulobov transformations given by: \hat{a}(t,k) = \alpha(t)a(k) + β(t)b^{\dagger}(-k)...

I would like to impedance match a few joints in a circuit and would appreciate some thoughts about this, since I would like the match to be as perfect as possible. The problem is complicated by the fact that the available equipment only consists of trimpot(s). The joints are mostly cables to...

Hi All, Good morning. we had a 20MW, 13.8 KV wye generator and it has a neutral grounding resistor. Some how we failed to connect the neutral grounding resistor and during a rain storm we burnt the generator. Even though the neutral is not connected to the neutral grounding resistor it was...

I have already asked this question at electronics.stackexchange but I still don't get it. I thought I understood it in terms of a water analogy but when I went back to electrons it still didn't make sense to me. My first reaction when encountering the idea of common grounding 2 separate power...

I am new with the topic Capacitors .I have read that a capacitor can be charged in two ways .One using the battery which I understand .The other is by charging one plate and grounding the other plate .I am not able to understand how this is done . Suppose +q charge is given to a plate ,say...

I have a nice and neat little PSU with a fuse from a DVD player, it outputs +/-12, gnd and +/-5 so 24 , 17 and 7 as well. The PCB had a 2 prong AC plug, probably with one bigger than the other. And on the PCB there is a place where a 3rd ground prong would be screwed on like on my printers PSU...

Hello. I have a tiny question that has confused me. Currently I'm reading about potential wells, harmonic oscillators, the free particle in quantum physics. If I just take the particle in a box as an example you have a region where the potential is zero, and you have some walls/boundaries...

This problem is 1.1b out of "Atomic Physics" by Budker, Kimball, and Demille. There are solutions in the book, but I am confused: I'm asked to find the ground state configuration of Phosphorus, which is has 3 P-state valence electrons. Following Hund's rule, we want to find a state with largest...

Hi I am taking generals now but I will eventually take EE degree. I am studying electrical systems now. Can somebody help me on system configuration regarding circuit breakers clearing ground faults? In this picture (the bottom figure), if X2 faults at the transformer, would the fault...

Homework Statement A shuttle is orbitting around the Earth at a velocity of (7.7x10^3) m/sec. The distance between a point on the Earth to the shuttle is (6.7x10^6)m. Calculate the speed of the shuttle relative to an observer on the earth. Completely lost! I was able to solve the...

For a particle with a force acting on it whose potential is given by U(x) = g*lnx for x>1 and U(x) = ∞ for x = 1, how do I calculate the ground state energy of the particle? Supposedly, there is no need to use Schrodinger's equations for this question, which is why I have no idea how to start...

Homework Statement Homework Equations E_{1}=<ψ_{1}|V(r)|ψ_{1}> The Attempt at a Solution That is equal to the integral ∫ψVψd^3r So I'll just perform the integral, correct ? But r is not constant here right? So, I' ll keep it inside the integral? How should I continue? Please...

If you lie on the ground at night with no cover, you get cold rather quickly. Much of this is due to energy loss by radiation. At night in a dry climate, the temperature of the sky can drop to -40oC. If you are lying on the ground with thin clothing that provides little insulation, the surface...

If you drop your shoe and a coin side by side, they hit the ground at the same time. Why doesn't the shoe get there first, since gravity is pulling harder on it?

With what initial velocity must an object be thrown upward (from ground level) to reach the top of the Washington Monument (approximately $550$ft.) well since $f(t)=-16t^2+V_0 t+S_0$ then $550=f(t)$ also, that $f'(0)=V_0$ and $f''(t)=-32$ this is supposed to be solved by using integration...

Homework Statement What is the energy of H atom in the first excited state if the potential energy in the ground state is taken to be 0 ? Homework Equations Usually the energy of H atom in the ground state is -13.6eV and in the 1st excited state is -10.2eV E(n) = πme2/8ε2h2 Bohr's...

I have made a focused effort over the past couple years to understand this "miracle" of quantum mechanics that has changed the civilization we live in, and frankly, I'm getting a bit frustrated that I am not privy to, as most popular TV physicists seem to purport, the obviousness of the...

I'm wondering why the gases don't stick to the ground like liquids and solids do. I read that gravity is pulling on the molecules but because of the electrons, the molecules repel each other. There's also something called "Brownian motion", what's that? And if they repel each other, why don't...

Homework Statement An electron is trapped in an infinite square-well potential of width 0.5 nm. If the electron is initially in the n=4 state, what are the various photon energies that can be emitted as the electron jumps to the ground state?Homework Equations ΔE=13.6(1/nf2-1/ni2)...