Ground Definition and 945 Threads

  1. D

    I 2D LHO calculate ground state energy

    A question I have faced in exam to calculate ground state energy Given Hamiltonian 1/2m(px2+py2)+1/4mw2(5x^2+5y^2+6xy) ground state energy has to be obtained Its clear that the Hamiltonian is a 2D LHO Hamiltonian but what for the term 3/4(x+y)2
  2. TheBigDig

    Expectation value of mean momentum from ground state energy

    1. The problem statement Consider a particle of mass m under the action of the one-dimensional harmonic oscillator potential. The Hamiltonian is given by H = \frac{p^2}{2m} + \frac{m \omega ^2 x^2}{2} Knowing that the ground state of the particle at a certain instant is described by the wave...
  3. Pushoam

    Which cylinder reaches the ground first?

    Homework Statement [/B]Homework EquationsThe Attempt at a Solution The correct option is d because which body will fall first depends on the moment of inertia, the less MOI, the fast the body reaches the ground. COM motion will not be applicable here as the friction force will be different...
  4. T

    If you roll when you hit the ground you feel less velocity?

    Rolls or brake falls slow down how fast your body hits the ground by well rolling.How does this decrease impacted.
  5. WeiShan Ng

    I Why drop the vibrational ground state energy

    This is from *Statistical Physics An Introductory Course* by *Daniel J.Amit* The text is calculating the energy of internal motions of a diatomic molecule. The internal energies of a diatomic molecule, i.e. the vibrational energy and the rotational energy is given by...
  6. M

    Capacitors in Hybrid-pi Model and Frequency Response

    This is what I have and I was wondering where C2 might go if I make apply the hybrid pi model on this circuit. I know that all the DC Voltages should be shorted if I were to make use of an equivalent circuit, so that in the hybrid pi model R1 should be in the input and R3 in the output. But what...
  7. yrjosmiel

    Speed of objects as they hit the ground

    Let's say there are two objects. One is thrown directly downward at v0 and the other is thrown horizontally (90 degrees) at v0, both from height h. Which object will have a higher speed by the time they hit the ground? Would they have the same speed? For the object thrown downward... h = (vf2 -...
  8. H

    How does the reaction force of friction affect the ground?

    Suppose I am trying to push a heavy block on ground and I haven't applied a force stronger than the maximum static friction. The force of friction acts on the block and its equal and opposite force acts on the ground. Does the reaction force of friction(acting horizontally on the ground)...
  9. Noisy Rhysling

    1,000 mph four inches off the ground

    Yeah, the Brits are going to build a car that can potentially hit 1,000 miles an hour. Or a tiny bug and go cartwheeling into the next country. Bloodhound supersonic car fires up Eurofighter engine By Jonathan AmosBBC Science Correspondent The Bloodhound supersonic car has been fired up for...
  10. J

    C/C++ Java vs wxWidgets or GTK+ with c++ for a PC ground station

    I've got experience with win32API but its' a pain in the ass. What else is good for cross platform low level programming of apps, want it to work for PC, linux, be able to handle serial data streams, convert data and do C++ tier things. So far been using processing but that's not powerful...
  11. G

    Would high voltage DC power grids work the same?

    Hi. As far as I know, the main reason for using AC in electric power transmission is that voltage can easily be transformed. If there was a similarly easy way for transforming DC, would power grids work basically the same? To be more specific, how much does AC power transmission rely on the...
  12. A

    Transient Heat transfer from water through pipe to ground

    Hi I am trying to do a transient heat transfer calculation. The water flowing through the pipe is laminar (1 m/s, id = 0.0127 m, Re_d = 0.01) transferring heat to the pipe via convection, then the pipe (od = 0.015875 m, l = 144 m) transfers heat to the ground again via conduction. I found this...
  13. S

    Ball Release and Thrown to reach ground at the same time

    Homework Statement A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof 1.00s later. You may ignore air resistance. If the height of the building is 20m, what must the initial speed of the first ball be if both are to hit the ground at the...
  14. Pushoam

    Minimum acceleration of a car at which front wheels leave the ground

    Homework Statement Homework EquationsThe Attempt at a Solution I assume that the wheels are 8ft apart in both x and y direction. Let's denote the length and width of the car by 2l = 8 ft. The torque about an axis connected the contact points of rear wheels : ##\vec \tau = [\{l( \hat x +...
  15. hilbert2

    A Several ground state calculations at once

    Suppose I want to find the ground states corresponding to several Hamiltonian operators ##\left\{ \hat{H}_i \right\}##, which are similar to each other. As an example, let's take the ##\hat{H}_i##:s to be anharmonic oscillator Hamiltonians, written in nondimensional form (##\hbar = m = 1##) as...
  16. teroenza

    Virtual Ground Voltage Reference

    I'm building an Arduino voltage logger that includes an op-amp (OP27G) as a buffer on the input. Since I'd like to be able to measure voltages all the way down to zero, I want to power the amp with a bipolar supply. My initial thought was to build the rail-splitter below so I wouldn't have to...
  17. aatari

    Projectile Problem - Bullet from Raised ground

    Hi Guys, could someone kindly look at my solutions and let me know if I did everything correctly. Thanks a lot! 1. Homework Statement A sniper fires a bullet at 120 m/s at 30° above the horizontal from the roof top of a 35 m high parking garage. If the bullet strikes the level ground beside...
  18. J

    Find the tension in the cable and reactive forces at ground

    Homework Statement A 160-kg utility pole extends 12m above the ground. A horizontal force of 250 N acts at its top and the pole is held in the vertical position by a cable, as shown in the figure (I have attached the photo). 1) draw a free-body diagram for the pole 2) Determine the tension...
  19. Arup Biswas

    B How do electrons behave when energy is added to an atom's ground state?

    Yah electrons existing the lowest possible energy state! Now suppose, we throw a beam of light towards a ground state of a atom. I heard/know electrons will take up energy from the photon "hv", and go to the next energy level i.e. excited state. Now my point is, is it only the valance electron...
  20. F

    How Did This Guy Make a Soccer Ball Wobble On the Ground?

    Hello, Hello, I found this youtube video that I have been trying to figure out how they did for a while. Being the good men of science that you guys are, I figured you might be able to explain how he did this: I tried: Filling the ball with water(which worked at slower speeds) Over inflating...
  21. M

    Understanding Voltage Between Hot and Ground in Electrical Connections

    How exist voltage between hot and ground? How we are connected to ground through wood floor, building when we use tester screwdriver?
  22. J

    Off center fed dipole input impedance vs height above ground

    I have a question for the community. I am doing a further study and trying to locate any information regarding input impedance of an off center fed dipole at different heights above ground. A simple dipole targets 73.1 ohms for 1 wave length or higher above ground. I am not sure if the same...
  23. N

    A Driven Harmonic Oscillator where Mass Hits Ground

    I started to ponder following problem. I have a driven, damped oscillator where the mass is free to vibrate in y-direction. If I put a wall or a ground near the mass, the mass touches it if the drive amplitude is larger than the distance to the ground. How does this change the normal dynamics. I...
  24. Kevin McHugh

    Satellite temperature data vs ground based data

    I've read in the popular media that there is a difference between the two. Is this true, and if so, why?
  25. A

    Fourier transform of the ground state hydrogen wave function

    Hi! 1. Homework Statement From the website http://www1.uprh.edu/rbaretti/MomentumspaceIntegration8feb2010.htm we can see the Fourier transform of the ground state hydrogenic wave function : Φ(p) = ∫ ∫ ∫ exp(-i p r) (Z3/π )1/2 exp(-Zr) sin(θ) dθ dφ r² dr (1.1) After intregation...
  26. ShayanJ

    A UV and IR modes in ground state

    I'm trying to understand chapter 19 of these lecture notes. But I have some difficulties with what the author explains: 1) In page 176, under equation 19.3 he says: This is weird. If we are considering a local QFT, then how can he say IR physics can cause non-locality? What is he talking...
  27. JulienB

    Stark effect: find ground state

    Homework Statement Hi everybody! I have a problem related to first-order perturbation theory, and I'm not sure I'm tackling the problem correctly. Here is the problem: Consider a hydrogen atom in an externally applied electric field ##\vec{F}##. Use first-order perturbation theory to find the...
  28. C

    Falling Cantaloupe - Distance Above Ground

    Homework Statement A cantaloupe with a mass of 0.45 kg falls out of a tree house that is 5.4 meters above the ground. It hits a tree branch at a speed of 6.3 m/s. How high is the tree branch from the ground? Homework Equations ## \Delta h = \frac {v_i^2 - v_f^2} {2g} ## The Attempt at...
  29. ikihi

    A hydrogen atom transitions from n= 5 state to the ground state

    Homework Statement A hydrogen atom transitions from ni= 5 state down to the ground state. a) What is the energy of photon emitted from the transition of the hydrogen atom? b) What is the ratio of the momentum of the emitted photon to the momentum of an electron which possesses the same kinetic...
  30. G

    Does current flow back to the power plant through the ground?

    Hi. I fear I might not have understood some fundamental concepts about electric power transmission. So we have "neutral" which is brought to Earth potential. Does this mean the electrical circuit from the power plant over highly conductive aluminium cables to my home closes back to the power...
  31. C

    I How can an atom change from ground to excited state?

    I am currently studying a Foundation Program, which includes chemistry. -I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration. -But how can an tom changes from ground to excited state ? And can an atom changes from...
  32. S

    Discharge of a capacitor through a common ground

    Let's say a switch causes a capacitor to charge and the switch opening causes the capacitor to discharge from its positive plate through a common ground to its negative plate. This common ground is connected to other components, if there is a difference in potential in other components to the...
  33. G

    Neutral potential ground difference

    Im studying a application where multiple 12V input voltage are coming into a circuit board, i was told that optocouplers are use to neutral the potential ground difference of the input 12V from various appliances. can someone explain to me how does the potential ground of each appliances varies...
  34. Grey_Thunderhead

    Find ground speed and direction of airplane

    Homework Statement [/B] "An airplane is flying on a bearing of 340 degrees at 400mph. A wind is blowing at a bearing of 320 degrees at 30mph. Find ground speed and direction of the plane." Homework Equations vx=vcosϕ vy=vsinϕ The Attempt at a Solution [/B] First, my teacher told us to change...
  35. U

    Which is better -- amp ground connected to frame or battery?

    There is this debate in car audio forums of this question whether it is better to connect your amp ground to the frame of the car or the battery.. basically they haven't came to a conclusion so I was curious what you guys think... Basically what I mean is that when you hook up an amp in the...
  36. A

    Poisson's Equation for Charge above Infinite Ground Plane

    I want to solve the Poisson equation for a thin slab of charge held above a grounded plane at z=0. The problem is somewhat reminiscent of the classical image problem of a point charge above an infinite grounded plane but differs because we are using a slab of charge instead which extends above...
  37. S

    Putting rotating cylinder on the ground

    Homework Statement We put a cyllinder with unknown mass and radius 0.1m which rotates with angular velocity 10 /s around its geometric axis on the horizontal ground. After what time does the cyllinder roll without slipping? Coefficient of friction is 0.1. Homework Equations F=ma M=J ⋅ ∝ The...
  38. D

    Direction of force exerted by ground for the ladder problem

    This question pertains to the classic ladder-leaning-against frictionless wall scenario. The system is in static equilibrium. The ladder is thin and can be assumed to be made of a homogeneous material so that the center-of-mass lies at the geometric center. The forces in this scenario is...
  39. Priss80

    Personnel Ground wrist strap Connection (non- monitored)

    In ANSI/ ESD S20.20 standard, do you know what "Personnel Ground wrist strap Connection (non- monitored)" test for? Regards, priss
  40. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    Homework Statement sportsman jumps at 5m/s velocity from 5m cliff to water. at what speed does he reach water? so given answer is 11.1m/s though in this book there are some wrong answers (I did try other equations and I got right answer but I want to know why I can't get it using this one)...
  41. K

    Grounded conductor and Electric field potential question ?

    Homework Statement [/B]Homework Equations V= kq/r.[/B]The Attempt at a Solution For 8-8, I do not really know how to approach it. For 8-14 , I think that q2=-q1 and q3=q1+q2. I can now use V=kq/r and then find the equations for r>R3 , r=R3 , R2<r<R3 , r=R2 and R1<r<R2 and then graph...
  42. hilbert2

    A Overlap of Ground States in Quantum Field Theory

    I was reading Peskin&Schroeder's QFT book, and there was some discussion about how ##\left|0\right>##, the ground state of a free field and ##\left|\Omega \right>##, the ground state of an interacting field differ from each other, and they outlined how the latter can be obtained by propagating...
  43. astrocytosis

    Using Hund's rules to find ground state L, S, J

    Homework Statement Using Hund's rules, find the ground state L, S and J of the following atoms: (a) fluorine, (b) magnesium, and (c) titanium. Homework Equations J = L + S The Attempt at a Solution I'm having trouble understanding what L, S and J mean on a basic level. I read the textbook...
  44. ShayanJ

    A Ground state wave function from Euclidean path integral

    From the path integral approach, we know that ## \displaystyle \langle x,t|x_i,0\rangle \propto \int_{\xi(0)=x_i}^{\xi(t_f)=x} D\xi(t) \ e^{iS[\xi]}##. Now, using ## |x,t\rangle=e^{-iHt}|x,0\rangle ##, ## |y\rangle\equiv |y,0\rangle ## and ## \sum_b |\phi_b\rangle\langle \phi_b|=1 ## where ## \{...
  45. farolero

    B Relativity: Curving of Space & Mass Inflation Explained

    so i take that the apple doesn't fall but that the ground acelerates up by relativity this means the Earth inflates at a certain rate thing not noticed for the measure instrument inflates simultaneously but we feel the inertia effects of the ground moving up making things fall and keeping us...
  46. X

    Probability wave function is still in ground state after imparting momentum

    Homework Statement An interaction occurs so that an instantaneous force acts on a particle imparting a momentum ## p_{0} = \hbar k_{0}## to the ground state SHO wave function. Find the probability that the system is still in its ground state. Homework Equations ##\psi _{0} =\left(...
  47. F

    How does a ground loop and a floating ground work?

    Hello Forum, In DC circuits, I understand that a ground is a point or an entire conductor where the electric potential is set to be V=0 and the potential V at any other point in the circuit is referenced to that. How does the the concept of ground loops work? Why are they not desirable? What...
  48. Christofferk

    Kinetic energy of the hydrogen atom in its ground state

    I saw another post about this but i didn't quite find what i was looking for there so i thought i'd give it a go instead with a thread. Homework Statement Calculate the exact value of the kinetic energy of the hydrogen atom in its ground state. No more information is given, we are referred to...
  49. K

    Why wind turbines don't have their dynamos closer to ground?

    Why don't the electric generator mount closer to the ground. The advantage I can think is that it is easy to maintain(no need to climb) and reduce weight(reduce tower cost), however the extended shaft will cost more. Does the longer shaft cost out weight the easier maintenance and generator...
  50. Justas

    Vertical throw initial height 15 time 3s until hiting ground

    Homework Statement Height - 15m Time when ball hits the ground after upward throw 3 s. I have been trying to find intitial speed with these formulas : d=v_initial*t-0.5*g*t^2 and v=v_initial+g*t Please help to understand how to find initial speed and after what time the ball is at 15m height...
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