Ground Definition and 950 Threads

  1. G

    Which Ball Lands First on the Moon?

    Which would hit the ground first if dropped from a certain height onto the moon, where there is no air resistance? A wooden ball 1 cm in radius, or a lead ball 1 cm in radius?
  2. K

    Ground state of harmonic oscillator

    Homework Statement Verify that the ground state (n=0) wavefunction is an eigenstate of the harmonic oscillator Hamiltonian. Using the explicit wavefunction of the ground state to calculate the average potential energy <0|\hat{v}|0> and average kinetic energy <0|\hat{T}| 0> Homework...
  3. D

    What Are the Final |L,S> States After Ground State Pionic Atom Decays?

    Homework Statement A pion is a spin-0 particle with a negative unit charge. A neutron is a spin-1/2 particle with no charge. A proton is a spin-1/2 particle with positive unit charge. One can construct an unstable version of the hydrogen atom where the nucleus contains both a proton and a...
  4. T

    Vector Operations - Resultant Ground Speed and Direction of Plane

    Homework Statement An airplane is traveling with airspeed of 225 mph at a bearing of 205 degrees. A 60 mph is blowing with a bearing of 100 degrees. What is the resultant ground speed and direction of the plane? Homework Equations x = u cos(degrees) y = v sin(degrees) However, I think the...
  5. C

    How long it takes for the ice block to hit the ground

    Homework Statement 5kg of ice falls away from the edge of the roof of a block of flats, at a height of 26m above the ground. Homework Equations ignoring the air drag, find out: a) how long it takes for the ice block to hit the ground. b) what is the speed at which the ice block hits the...
  6. D

    Circuit with just a battery and ground

    What would happen if you just hook up a battery to itself, and a ground? I understand resistance is negligible in wires when there are other resistors, however, this doesn't seem to be the case when this occurs. But what happens? Battery drains extremely fast ?
  7. D

    Bohr Radius and Ground State Energy

    Homework Statement Given the potential energy V(r)=-\frac{1}{4\pi \epsilon_0}\frac{e^2}{r} (where e is the unit charge), use the uncertainty principle \Delta x \Delta p \geq \hbar to find the Bohr radius r_B for a hydrogen atom and the ground state energy E_0. Hint: write down the kinetic...
  8. K

    Speed of an arrow using distance and angle with the ground

    Homework Statement You are watching an archery tournament when you start wondering how fast an arrow is shot from the bow. Remembering your physics, you ask one of the archers to shoot an arrow parallel to the ground. You find the arrow stuck in the ground 68.0 m away, making a 3.00o angle...
  9. T

    What is the speed of the rock right before it hits the ground?

    Homework Statement A boy kicks a rock off a cliff with a speed of 19.4 m/s at an angle of 52.5° above the horizontal. The rock hits the ground 5.41 s after it was kicked. a) How high is the cliff? (60.3 m) b) What is the speed of the rock right before it hits the ground? c) What is...
  10. P

    Term ground mean in an ELECTRONIC circuit?

    term "ground" mean in an ELECTRONIC circuit? What does the term "ground" mean in an ELECTRONIC circuit? A bus strip usually contains two columns: one for GROUND and one for a supply voltage. What does ground mean in this context and how do we ground a circuit while using a breadboard?
  11. A

    Finding the ground state energy of electron

    1) The problem is about finding the ground state energy of electron in an infinite 2D circular and square potential well with the same area. I have calculate it via method of separation of variables in polar and cartesian coordinate respectively, and it is found out that the one on the circular...
  12. S

    Bringing wind energy to the ground through a giant pitot tube

    Ok not a great title, but let me try to explain the idea. Imagine that you have say a parachute attached to the top of a flag pole. In the center of the parachute a hole is cut and connected to a plastic tube that goes to the ground. When the wind comes up the parachute exerts a drag on the...
  13. G

    Momentum-an egg dropped on the ground vs. grass

    Homework Statement an egg dropped on the road breaks, while the egg that is dropped on grass doesn't break...why? a. the change in momentum is greater b. change in momentum is less c. the time interval for stopping is greater d. time interval for stopping is less Homework Equations...
  14. K

    Ground state wavefunction real?

    Hi.. In a textbook, the ground-state wavefunction for any general Hamiltonian was under consideration. Then, a statement was made that this wave function is real since it is the ground state. Is it true that one can always choose the ground state wave function to be real? I understand...
  15. M

    Ground state energy of nucleus

    How do we compute the energy of the ground state using nuclear shell model?
  16. S

    Calculating max. speed of car over humpback bridge before it leaves the ground?

    Homework Statement A car travels over a humpback bridge of radius of curvature 45m, what is the max speed it can reach before the wheel lose contact with the road? Homework Equations mg - R = (mv^2) / r The Attempt at a Solution When the car is about to lose contact with...
  17. A

    How long time until it hits the ground

    Homework Statement A boy on a roller coaster dropped his shoe after 0,10. How long time will it take until his shoe hits the ground. The roller coasters acceleration is 34,37m/s^2 Homework Equations First i started looking at a = delta v / delta t The Attempt at a Solution I...
  18. S

    Can anyone confirm the ground state Bohr radius for muonic hydrogen?

    Thanks in advance for anybody who is kind enough to help me. No this isn't for my homework. I am not even enrolled in school. I am doing some calculations for personal research. But I need to know the ground state radius of a muonic hydrogen atom to help prove my theory. I already know the...
  19. H

    Changing Rotation Speed of an Acrobat Not on the Ground

    Homework Statement If an acrobat isn't touching the ground how can he changes his rotation speed? Homework Equations The Attempt at a Solution
  20. S

    Ground state magnetic moment of 7Li

    Homework Statement Calculate the ground state magnetic moment of 7Li using the below equations. The spin value is 3/2. Homework Equations mu_J = gamma_J * J* hbar = g_J * u_N with g_J = [g_l + (g_s - g_l)/(2l + 1)] where g_l and g_s are orbital and intrinsic spin g factors for...
  21. P

    Classical ground state is Ne\'{e}l state:

    Tha classical ground state is Ne\'{e}l state: every spin up is surrounded by nearest neighbours which are down, and vice versa. To give them a name, denote the spins down the A sublattice, and the spins up the B sublattice. Perform a canonical transformation on the B (but not on the A spins...
  22. T

    Problems with multiple ground connections

    Homework Statement What are some problems that can occur if two pieces of equipment both are connected to mains earth? Homework Equations The Attempt at a Solution If they are connected to common ground, ground loops or low impedance loops can occur. Ground loops can cause stray...
  23. P

    Muonic hydrogen ground state energy

    Would the energy just be a multiple of how much bigger it is than electron?
  24. O

    Ground State Parity in One-Dimensional Potentials

    Must the ground state in an even potential of one dimension be the even parity?
  25. G

    Change of sea level in relation to sea ground

    My physics teacher said that if the sea ground is higher, then, because of the stronger gravitational force, the sea level is lower. I am not sure if this is true and he didn't give a very strong proof. I thought sea level equalizes all over the earth. Of course I am taking the sea level in...
  26. B

    Spectroscopic term of ground state electron configuration of Carbon atom

    The ground state electron configuration of Carbon atom is 1s^{2}2s^{2}2p^{2} For the electrons, 1s^{2}2s^{2}, L=0, S=0 So only consider electrons of 2p^{2}, and s_{1}=s_{2}=1/2 ---> S=0,1 l_{1}=l_{2}=1 ---> L=0,1,2 For S=0, L=0; J=0, so we have ^{1}S_{0} For S=0, L=1; J=1, so...
  27. I

    Analyzing a Finite Potential Well: Estimating Ground State Energy

    Homework Statement An electron is confined to a potential well of finite depth and width, 10^-9 cm. The eigenstate of highest energy of this system corresponds to the value \xi = 3.2. a. How many bound states does this system have? b. Estimate the energy of the ground state with respect...
  28. H

    Simulation of the sun's effect on temperature change on the ground surface

    Hi, I am working on simulating the change in temperature over time for the ground, given different material types. For instance, I'm considering an asphalt patch of ground say 10 square meters in area. For now, I'm willing to ignore atmospheric effects like rain, wind, and varying sun...
  29. K

    Total ground state energy of N fermions in a 3D box

    Hello everybody, I just have no idea how to start this problem so i was hoping you guys would point me in the right direction and then i'll be able to go on by myself the problem asks to show that the total ground state energy of N fermions in a three dimensional box is given by E total =...
  30. R

    Empty conducting cube with 4 sides at ground and 2 sides at V

    Homework Statement Empty cubic box of dimension "a" with conducting walls. Two opposite walls are held at a constant potential V, while the other walls are grounded. Find an expression for the electric potential inside the box. (Assume box centered on the origin, walls are all normal to one...
  31. M

    Finding the Ground State of a Hamiltonian Operator

    When given a Hamiltonian operator (in this case a 3x3 matrix), how do you go about find the ground state, when this operator is all that is given? By the SE when have H\Psi=E\Psi. I can easily solve for Eigenvalues/vectors, but which correspond to the ground state, or am I missing something?
  32. F

    Perturbation Theory - Shift of Ground State

    Homework Statement Use leading order perturbation theory to calculate the ground state shift of hydrogen due to perturbation: \hat{V} Homework Equations 1. Leading terms in expansion of energy: E=mc^{2}+\frac{p^{2}}{2m}-\frac{p^{4}}{8m^{3}c^{2}}+... 2. \hat{H}=\hat{H}_{0}+\hat{V} where...
  33. H

    Would an hourglass on a rocket going up empty faster than one on the ground?

    Just wondering. Would appreciate any input! :)
  34. V

    Probability of being in ground & 1st excited state of widened infinite well

    Homework Statement A particle is initially in the ground state of a one-dimensional infinite square well extending from x=0 to x = L/2. Its wave function, correctly normalized, is given by \psi (x) = \dfrac{2}{\sqrt{L}} \sin{(\dfrac{2 \pi x}{L})}} for 0 \leq x \leq L/2 Suddenly, the right hand...
  35. A

    Estimating the Number of Balloons Needed to Lift You Off the Ground

    Homework Statement To an order of magnitude, how many helium-filled toy balloons would be required to lift you off the ground? Helium is an irreplaceable resource so develop a theoretical answer rather than an experimental one. Homework Equations ? The Attempt at a Solution...
  36. W

    Schrodinger ground state wave function

    Homework Statement Find the ground state wave function for the 1-D particle in a box if V = 0 between x = -a/2 and x = a/2 and V = \infty Homework Equations I would guess -- Schrodinger's time-independent equation...
  37. G

    Hat height from the ground will the child become airborne? picture included

    Homework Statement A poorly designed playground slide begins with a straight section and ends with a circular arc as shown in the figure below. [PLAIN]http://img716.imageshack.us/img716/8381/25746193.jpg A child starts at point P and slides down both sections of the slide. At some point on...
  38. H

    Projectile motion. how long does it take for the projectile to git the ground?

    I have no idea on where to start with this. Also we are not allowed to use The normal physics equations, we have to use maths. At time t = 0 a projectile is fired from a height of h above level ground at an elevation angle of a and a speed of v. Show that the time when the projectile hits...
  39. K

    Pulley with string attached to ground

    Not exactly a homework question, but I need to know this before I can answer the question Homework Statement There's a pulley suspended from a rope A. Hanging from the pulley from one side is a mass m. "Hanging" off the other side of a pulley is simply the same rope (which is attached to...
  40. H

    Electrons vs Ground: What's the Difference?

    I know that electrons want to flow to ground (earth ground) so I have a few questions: Is it only AC current that flows to ground(I ask this because I saw a video of a person with a Tesla coil on their car and the electricity was going to the ground)? If I put the -(negative) side of a 9V...
  41. Shackleford

    Calculate probability electron remains in ground state of He3.

    I'm not sure how to calculate the probability in a non-hydrogenlike atom. Perhaps I'm missing something. Z=1 to Z=2. Of course, n, the principal quantum number is n and l would be zero. http://i111.photobucket.com/albums/n149/camarolt4z28/2010-09-23195548.jpg?t=1285517610
  42. C

    A ball is shot from the ground into the air and horizontal distance

    [b]1. The problem statement, all variables and given/known da A ball is shot from the ground into the air. At a height of 9.7 m, the velocity is observed to be v = (7.4)i + (5.1)j in meters per second (i horizontal, j upward). Homework Equations What will be the total horizontal distance...
  43. P

    How Is Torque Related to Frictional Force?

    I am trying to figure out how exactly Angular friction ("torque") is connected with friction force. Is there any connection between torque friction and force friction?
  44. L

    What's the Difference Between Ground Lead Screws and Lead Screws?

    What's ground lead screws ? What's the differences between the ground lead screws and lead screws ?
  45. J

    Symmetry of the Bloch Ground State

    I was reading Hasan & Kane's review on topological insulators and right in the beginning, page 3, they say that the Bloch ground state is U(N) invariant. I do not see that. Would anyone be able to show it or point to a reference? Thanks, Jan.
  46. G

    What is the speed of the ball just before it strikes the ground?

    A ball is thrown from the top of a building upward at an angle of 47 ◦ to the horizontal and with an initial speed of 23 m/s, as in the figure. The ball is thrown at a height of 46 m above the ground and hits the ground 82.0127 m from the base of the building. The acceleration of gravity...
  47. O

    Calculating Time for Crate to Hit Ground After Falling from Cargo Plane

    Homework Statement A cargo plane is flying horizontally at an altitude of 11.5 km with a speed of 860 km/h when a large crate falls out of the rear loading ramp. (Ignore any effects due to air resistance.) (a) How long does it take the crate to hit the ground? Homework Equations...
  48. S

    What is an "Isolated Ground" Outlet?

    I've seen many 'isolated ground' outlet, in schools and hospital. Tried to google it but didn't find much information about those. They're and orange case, and usually are just beside the normal mains. What is special about those? Are they safer? Thanks, Sakha.
  49. S

    Why is it that it's the gravitational force that keeps me on the ground?

    Why is it that it's the gravitational force that keeps me on the ground? Rather than the electrical force? In general, and by the equation, electrical force is much stronger than the gravitational force!
  50. A

    DC Blocking capacitor - How does it know where ground is?

    DC Blocking capacitor -- How does it know where ground is? Hi Everyone, A DC blocking capacitor removes any DC offset from an input signal. I've been doing this for years without thinking about it. My question is, how does it know what the local ground potential is? My only thought on...
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