Ground Definition and 945 Threads

  1. EEristavi

    Why a DC power supply doesn't have a voltage with respect to ground?

    I see that DC power supply have voltage between it's + & - and its 24V. However, there is no voltage with ground. I don't understand - if device's "point" has some potential, why doesn't it give some voltage with ground (which has ~0 potential) I tried this with phoenix contact...
  2. L

    A Quantum statistical canonical formalism to find ground state at T

    For my own understanding, I am trying to computationally solve a simple spinless fermionic Hamiltonian in Quantum Canonical Ensemble formalism . The Hamiltonian is written in the second quantization as $$H = \sum_{i=1}^L c_{i+1}^\dagger c_i + h.c.$$ In the canonical formalism, the density...
  3. DrClaude

    Power lines connecting to the ground

    This is going to be a very basic question, but something that has bothered me for a while. It was triggered again by this thread from @OmCheeto: https://www.physicsforums.com/threads/new-deccan-trap-turns-out-to-be-downed-power-line.970313/ Why is it that when a power line is downed, there is...
  4. cianfa72

    Electric potential difference between a battery's + terminal and the ground

    Hi, I've a question about electricity in the following scenario: consider an accumulator (e.g. a 9V battery) and an analog/digital voltmeter having a probe connected to the accumulator + clamp and the other to the ground (for instance connecting it to a metal rod stuck in the ground). Do you...
  5. thaiqi

    I Doesn't the atom in ground state radiate?

    According to textbooks, an atom in ground state doesn't radiate. Yet I got some other idea after reading Wu Ta-you's theoretical physics book. I hold the viewpoint that the atom does radiate, and at the same time it absorbs energy from heat radiation in its environment. The energy it radiates...
  6. bobg123

    Engineering Circuit input impedance with ground in an OP Amp circuit

    I've been given the following circuit and have been asked to find the input impedance and the impedance between the input terminal and ground. I've never encountered an operational amplifier configured like this. I know that the voltages at the - and + terminals of the op amp are ideally equal...
  7. O

    Statistics physics problem -- atom is in the ground state or excited state?

    I am learning for my exam in particle physics. One topic is statistical physics. There I ran into this question: Consider an atom at the surface of the Sun, where the temperature is 6000 K. The atom can exist in only 2 states. The ground state is an s state and the excited state at 1.25 eV is a...
  8. J

    MHB Solving Minute Hand Distance from Ground Graph Problem

    I'd like to know how to solve this. I'm pretty lost as to how to solve this. I want to say that the graph would look periodic because of the graph of the time would go down and then go back up again, but I really don't have anything concrete. The question states: The circular clock has a...
  9. S

    Mousetrap car won't roll on ground but will when being held

    I have made multiple mousetrap cars, and they've all have the same problem. They all have rolled when I held them however when I would put them on the ground they would not go. I think the problem may be a friction problem, however I'm not sure. I don't know what to do. Any advice/help would be...
  10. Alexanddros81

    A jet comes in for a landing on solid ground

    Homework Statement A jet comes in for a landing on solid ground with a speed of 100m/s, and its acceleration can have a maximum magnitude of ##5.00m/s^2 ## as it comes to rest. (a) From the instant the jet touches the runway, what is the minimum time interval needed before it can come to rest...
  11. Tracey3

    Capacitor on ground connection of Comparator input

    So I am stumped by why these capacitors are there, to my understanding the capacitor C3 acts as a low pass filter but then I don't quite understand the purpose of C1 and C2 as indicated on the picture.
  12. S

    Total energy of hydrogen at ground state

    Homework Statement What is the total energy of the hydrogen atom at ground state? a. 13.6 eV b. mpc2 + mnc2 c. mpc2 + mnc2 - 13.6 eV d. mpc2 + mnc2 + 13.6 eV Homework Equations E =...
  13. Specter

    Velocity of the ball when it hits the ground, limits?

    Homework Statement [/B] The path of a baseball relative to the ground can be modeled by the function ##d(t)=−t^2+8t+1## , where d(t)represents the height of the ball in metres, and t represents time in seconds. What is the speed of the ball when it hits the ground? Homework EquationsThe...
  14. S

    Airplane Landing Questions -- How can the pilot see the ground?

    The most nervous moments for me is during airplane landing when I'm concerned if the plane would just stall or hit the concrete so hard. So let me take this opportunity to understand it. How many commercial airliners use manual and automatic landing technology (in terms of percentage)? For...
  15. C

    Ground state and 1st excited state energy of 3 Fermions

    Homework Statement So in my problem, there's a given of 3 non interacting fermions in a harmonic well potential. I already got the wavefunction but i have problems in obtaining the ground state energy and its 1st excited state energy for 3 fermions (assuming they are non interacting and...
  16. Kevin J

    How do you calculate voltage drop across neutral and ground?

    In our practical world, the voltage between the neutral wire and the ground is not exactly 0V, and there's some small current passing through the wire connecting the neutral wire to the ground, how do you mathematically calculate this voltage drop?
  17. K

    Generator tripping on ground fault during load test

    We have been testing a Cummins VTA-1710-G2 Diesel Generator 1800 RPM 480 Vac 671 kW with an Avtron K580 load bank that is hooked up to our three 480 Vac output cables and one cable to our facility ground. The generator output breaker keeps tripping when the load is around 350 kW. The test...
  18. L

    I Estimate of ground state energy for the Yukawa potential

    I’ve seen the uncertainty principle used to calculate the ground state energy for things like hydrogen and the harmonic oscillator, but can this be done for the Yukawa potential where you have an exponential?
  19. W

    Ground current for a voltage regulator

    Homework Statement Homework Equations 3. The Attempt at a Solution [/B] Currently working on the question relating to the ground current on the voltage regulator, 7805 (data sheet included below) I am very much unsure what to calculate here I'm assuming the current to ground is the input...
  20. J

    I Is the Smallest Eigenvalue Always the Ground State Energy?

    If I diagonalize the hamiltonian matrix ,I can get the eigenvalues , does the smallest eigenvalue always be the ground state energy?
  21. M

    Ansys Maxwell -- how to ground an insulator?

    Can anyone guide me about how to ground an insulator using Ansys Maxwell 2015?
  22. W

    Engineering Grounding Op-Amp circuit exercise

    Homework Statement 2. Homework Equations 3. The Attempt at a Solution For the first set of questions: I've worked through to part 6), at which is I encountered my first problem. I'm not entirely sure what the question is asking. Is it as if there would be a capacitor between...
  23. C

    Other Building up an understanding and knowledge from the ground up

    Are there any books or a sequence of books I could study to build up a picture of what I can know for sure and why I can know it? I suppose that's what some people do when they study a subject and move from the basic principles to further stuff. So like, has anybody started with the smallest...
  24. Warda Anis

    Expectation value <p> of the ground state of hydrogen

    Homework Statement How should I calculate the expectation value of momentum of an electron in the ground state in hydrogen atom. Homework Equations The Attempt at a Solution I am trying to apply the p operator i.e. ##-ihd/dx## over ##\psi##. and integrating it from 0 to infinity. The answer I...
  25. Mzzed

    Connect isolated ground to Earth?

    I am currently working on a high power class E amplifier which will sit inside a metal enclosure. It is powered by two power supplies - both are isolated but one of the power supplies is mounted in the same enclosure. The power supply itself is in a metal case and that case is connected to...
  26. A

    A The half harmonic oscillator's ground state wave function

    For the half harmonic oscillator the ground state wave function is of the form x*exp(-x^2/2) But sir how to check it's parity and with respect to with point As this function is valid for positive x only Thank you
  27. S

    Airplane's motion relative to the ground involving wind speed

    Homework Statement Plane is 300miles E of chicago and it leaves flying east at 500mph. Wind is blowing 50mph south. What is planes ground speed? Where is plane 0.6 hours later when pilot expects to land in cleveland? Homework EquationsThe Attempt at a Solution This is how I set it up I want...
  28. Sushmita

    Ground state energy of 5 identical spin 1/2 particle

    Homework Statement The ground state energy of 5 identical spin 1/2 particles which are subject to a one dimensional simple harkonic oscillator potential of frequency ω is (A) (15/2) ħω (B) (13/2) ħω (C) (1/2) ħω (D) 5ħω Homework Equations Energy of a simple harmonic oscillator potential is En...
  29. Sushmita

    A particle of mass 'm' is initially in a ground state of 1- D Harmonic oscillator potential V(x)....

    Homework Statement [/B] A particle of mass 'm' is initially in a ground state of 1- D Harmonic oscillator potential V(x) = (1/2) kx2 . If the spring constant of the oscillator is suddenly doubled, then the probability of finding the particle in ground state of new potential will be? (A)...
  30. D

    Casting of ground beam and ground slab

    Homework Statement Guys, I was told that the ground beam can't cat together with ground slab ? Why ? Why for first floor , the beam can be casted together with ground slab ? Homework EquationsThe Attempt at a Solution I think the ground beam can be casted together with ground slab ... Am i...
  31. J

    I Is the ground state energy of a quantum field actually zero?

    I start by outlining the little I know about the basics of quantum field theory. The simplest relativistic field theory is described by the Klein-Gordon equation of motion for a scalar field ##\large \phi(\vec{x},t)##: $$\large \frac{\partial^2\phi}{\partial t^2}-\nabla^2\phi+m^2\phi=0.$$ We...
  32. prakhargupta3301

    What will be the acceleration of a 10kg block w.r.t. the ground frame?

    Homework Statement [/B]We have to find acceleration produced by 10 kg block on 5 kg block with respect to the ground. Downward acceleration of life is 5m/s-2 Homework Equations f=ma g=10m/s The Attempt at a Solution Effective force at play on 10 kg block: mg- ma...
  33. T

    I Dropped objects hitting the ground at the same time?

    okay, so I’ve had this random thought. We have all been told that objects fall to the ground at the same speed, even if they have different masses. While it’s true that any two objects, regardless of mass, will accelerate towards Earth at the same speed, that doesn’t mean the Earth is...
  34. Alexanddros81

    Determine the ground speed and the course of the plane

    Homework Statement 15.1 The airspeed of the plane is 200m/s, directed north. If the wind speed is 30m/s in the direction shown, determine the ground speed and the course (angle θ) of the plane. Homework Equations The Attempt at a Solution Is it so far correct the above? More questions...
  35. RicardoMP

    Ground state of 3 noninteracting Fermions in an infinite well

    In Zettili's Quantum Mechanics, page 477, he wants to determine the energy and wave function of the ground state of three non-interacting identical spin 1/2 particles confined in a one-dimensional infinite potential well of length a. He states that one possible configuration of the ground state...
  36. P

    How high was the package above the ground when it was thrown

    Homework Statement ( p 49 sterling) Ignoring air resistance, if it takes 16 seconds for a package to strike the ground, how high above the ground was a package when it was thrown upward from the stationary helicopter at 15 m/s per second[/B]Homework Equations V=Vo+at D=Vot+(1/2)at^2 The Attempt...
  37. NeedHelpBro

    Ground Speed of Plane in Windy Conditions

    Homework Statement A Jet is heading due east: its nose points towards the east direction, but its trajectory on the ground deviates from the east direction due to a sideways component of the wind. The plane is also climbing at the rate of 100 km/h (height increase per unit time). If the plane's...
  38. isukatphysics69

    Box lifted off the ground by a tension force at a 32 degree angle

    1. Homework Statement The magnitude of the force F is slowly increased. The direction of the force remains the same. What is the magnitude of the force F at the moment the block looses contact with the floor? Homework Equations fnet=m*a[/B]The Attempt at a Solution fnety =...
  39. Monoxdifly

    MHB [ASK] How long must he wait until the ball fall to the ground if g = 10m/s^2

    In a soccer match Putu kicked the ball with the elevation angle \alpha so that it reached the maximum height 10 m. How long must he wait until the ball fall to the ground if g = 10m/s^2? I don't know how to do it if the initial velocity isn't known. Can someone help me?
  40. M

    A How to construct a spin-3/2 theory from the ground up

    I'll start by saying I'm posting this in Beyond the SM just because we have no elementary spin-3/2 particles in the SM as far as we know, though I was also considering posting it elsewhere. If you feel it's more appropriate in another area just let me know. As for the question itself, I'd like...
  41. lekh2003

    How much ground counts as ground?

    I recently saw this joke where somebody attaches a ground wire to a small cup of soil and it got me thinking. How much ground really makes something able to be a ground. Would it be just a cup like the joke, a bucket, or would it require the actual Earth to ever be a real ground? Can you make...
  42. anorlunda

    What is the difference between Earth ground and circuit common?

    <<<Moderator's Note This thread was split form https://www.physicsforums.com/threads/are-the-terminals-of-a-battery-neutral.939947/>> because the grounding posts are interesting but off-topic to that other thread.>> The entire Earth (ground) might be charged plus or minus one million volts...
  43. neilparker62

    I Exploring the Ground State Lamb Shift: Advances and Controversies

    What exactly is the so-called "Ground State Lamb Shift". It seems to have been an 'in vogue' quantity up till 1995 or so - then vanished from the literature ?? It's the 'self energy' or something like that of an electron in H 1S orbital. A scientist (at NIST) told me it's a term that has gone...
  44. A

    I Ground State Energy of a Potential: λ2px2/2m+0.5kx2

    I am having a doubt that if Id lho potential is Given of the form λ2px2/2m+.5kx2 then whether the ground state energy of the system is λ2/4ħω+1/4ħω
  45. D

    A rocket needs to hover stationary over the ground

    Homework Statement A rocket (initial mass ##m_o##, constant exhaust velocity ##v_{ex}## needs to use its engines to hover stationary, just above the ground. a) If it can afford to burn no more than a mass ##\lambda m_o## of its fuel (##\lambda \lt##), for how long can it hover? b) If ##v_{ex} =...
  46. A

    What Does Ground Mean in Electrical Terms?

    I've never been given a clean cut explanation of ground. I've heard some people refer to it as a common return path for current. Another as being a relative point that has a potential of 0V. Sometime people say Earth ground which I'm pretty sure actually means the ground of the Earth (not...
  47. D

    Kinematic equation problem -- A fountain shoots water out of the ground ....

    Homework Statement 1. A fountain shoots water out of the ground at a 40° angle. It’s horizontal velocity is 2 m/s and the water lands 3 meters away. What is the maximum height that the water reaches during that time? Homework Equations Dy =vit + ½ at2 and Vfy2 = Viy2 + 2ady The Attempt...
  48. Nihal Jalal

    How do i learn math and physics from the ground up?

    I know there is a lot of questions like this in this community but I need a personalized answer. I am 15 years old. I've always loved physics and always asks questions. My wish for learning physics dates back to 2016. Yeah that's right, I've spend two years just looking for the right resources...
  49. S

    Two spheres of are dropped to ground while in contact.

    Two spheres of different masses are dropped to ground.They are in contact as one above the other and are of masses, let’s say m and 2m.They are dropped with velocity v - My question is if we can conserve momentum and if we can why?And how to find the final velocity of upper ball after collision...
  50. R

    Projectile motion above ground given only angle and height

    Homework Statement I'm having trouble with part A of this question 1. A ball is fired out at an angle of 30° from the platform of height h = 0.5 m as shown in Figure 1. It is subjected to the gravitational force only thus follows a projectile motion. It falls onto the ground after 0.6...
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