Ground Definition and 945 Threads

Question: 1. A clock is hanging on wall. length of minute hand is 16cm and the length is 8cm for the hour hand. The highest that the tip of the minute hand reaches above ground is 265cm. a) What is equation of axis, amplitude & period in minutes of function that represents the tip of hour...

Building a wireless energy transfer systems with a transmitting and receiving antenna. I have encountered a problem with what appears to be a floating ground. Initial testing is done with a normal LED that will only light when I have my finger touching one of the leads on the LED. Further...

Hi I noticed that certain workers were laying Pneumatic lines underground ( the lines will be covered with concrete) in a factory. I have no idea how much the pressure would be , or what safety precautions they are undertaking. The lines are used to power certain pneumatic tools ( Torque guns...

I had a curious thought today, here is my logic: Charged particles have E fields. Moving charged particles create B fields. Electrons are moving charged particles, oscillating in an atom. Therefore, I concluded that an atom must be creating an oscillating EM wave, even in the ground state. But...

Homework Statement A 500kg car drives of a 400m cliff located on the surface of the Earth how long does it take to hit the ground Homework Equations F=ma F=mg d=1/d at^2 The Attempt at a Solution i first did f=mg to find f then i did f=ma converted that to find a then did 1/2 at^2 converted...

Hello again everyone! I would like to ask a question regarding this Hamiltonian that I encountered. The form is H = Aa^+a + B(a^+ + a). Then there is this question asking for the eigenvalues and ground state wavefunction in the coordinate basis. The only given conditions are, the commutator...

My textbook tells me that balls don't randomly bounce upward because it is improbable that all of the thermal motion of the particles suddenly align in one direction (upward). But it is just improbable right, or is it impossible? I guess what I'm asking is, is entropy only a statistical...

I'm asked to show that in the ground state, a particle trapped in a potential well approximately equal to its lowest allowed energy. I know the expression for the energy is h^2/8mL^2 for a finite well, and ΔEΔt~h/2π. But I'm at a loss as to how I'm supposed to even begin to start this...

Forgive me if this seems a rather basic question, but I would like to settle it once and for all. The concept of "ground", "earth" and "common" confuse me a little. I think I have Earth right - this is a path that allows dangerous current to be carried away, eg. if a live wire touched the...

Homework Statement Use the uncertainty principle to estimate the ground state energy of a particle of mass "m" is moving in a linear potential given by V(x) = ∞ for x≤ 0 V(x) = αx for x ≥ 0 Homework Equations ΔxΔp ≥ h/2 The Attempt at a Solution I've looked at a similar problem...

Homework Statement A missile is launched from a fighter jet cruising horizontally at a speed of 280 m/s, at an altitude of 1800 m. The initial velocity of the missile relative to the fighter jet is 160 m/s, in the forward direction. The missile is powered by its own engine, which provides it...

Homework Statement A person trips against a table, causing a glass to fall off the edge. An excellent human reaction time is 0.25 seconds. In that time, how far wil the glass fall? Assume that immediately (after 0.25 s has elapsed) begin to acclerate your hand so that you grab the glass when...

Earth acts as an electrical ground for the electrical supply that come to our home. But the ground, usually made of cement or stone is not a conductor like metal then how does it acts as an electrical ground.

Homework Statement A ball is thrown downward from a height of 30m at 8m/s. How long until it hits the ground? (Air resistance is negligible and gravity is 9.8m/s Homework Equations I tried deltaX=Vi+(1/2)a(t^2) and came out with 2.12, but the solution says it's 1.79. The...

Noticed something interesting about my microphone today and can't stop thinking about it. So there's always been this humming noise with my microphone (I can clearly hear it since I am using headphones), but I've never really thought about it. Now suddenly today my foot touched the metal casing...

When a ping pong ball strikes the ground obliquely without spinning, the angle of incidence is not equal to that of reflection, am I correct? Here is my thoughts: Assume the ground is smooth and negligible air resistance. When the ball touches the ground, it starts to deform, delivering its...

Does anyone have the most up-to-date zero-point oscillation frequency for a hydrogen molecule? This is not a homework question, I'm thinking about incorporating it into a tattoo someday. I don't wish to have a tattoo with inaccurate info, so any help would be appreciated.

I install and repair coffee and espresso equipment and we sometimes run into electrical problems beyond my knowledge (well versed in household wiring, good with fundamental applications of ohms law, etc. but I'm no physics major!) The issue that comes up most often is dubious grounds, or...

I am working on a simple physics engine right now and when the object eventually comes to a rest, it starts 'twitching' (moving up/down slightly very quickly) because gravity pulls it through the floor, and then the collision detection pops it back up. Here is the order in which my simulation...

Ok so this is a problem that's been bothering me ever since the first few days of learning kinematics. We've been taught that when an object falls, the object has a positive velocity up until the moment that it hits the ground. At that moment, the velocity becomes zero. Wouldn't this imply...

hi i have been thinking about this scaling problem: Let me say a man and a cat jump from the top of a high building. both hit the ground, but as we all know the cat has a much higher chance to be alive after the collision. so is this caused by the biological or physical differences between...

Why does a projectile sitting on the ground travel further than a projectile launched on a cliff? As per HyperPhysics it said that sitting on ground a projectile at 15m/s and 40 degrees above the horizontal would travel +22 m but if you put on top of a 3 m high cliff, the range would be...

Homework Statement A mass 100.0 g is dropped from some height above the ground and rebounds to a point where it has 78% of its initial gravitational potential energy. As it hits the ground, it is moving at 1.2 m/s. What is the impulse imparted by the ground on the ball? Homework...

pls explain me the concepts of ac ground,dc ground and virtual ground.?

I was just wondering about chassis ground in the context of a cars electrical system. If the return path back to the battery is through the metal chassis of the car, then what stops you from receiving a shock when you touch the car chassis ? Thanks.

I noticed many PF threads mention ground state of Hydrogen atom. At the same time it is two body problem considered to be solved by separation of variables. It is true, of course, that we can find basis wave functions (solutions of Shroedinger equation). But why does anybody think, that...

Homework Statement Find the ground state (stable configuration at T = 0) of the one-dimensional ising model with first and second neighbour intercations: H = -J_1 \sum_{i} s_i s_{i+1} -J_2 \sum_{i} s_i s_{i+2} where s_i = \pm 1 The Attempt at a Solution I really don't know what i...

Homework Statement Find the ground state energy and the ground state wavefunction for a particle of mass m moving in the potential V=\frac{1}{2}mw^{2}x^{2} at x>0 V=\infty at x<0 The Attempt at a Solution Well, the problem I am having is that I have answering questions that always...

Homework Statement The wind is blowing from west to east at 35.0 mph, and a bird in that wind is flying at 22.0 mph relative to the air. What is the magnitude of the velocity of this bird relative to a person standing on the ground if the bird is flying from west to east relative to the...

If a hot power line hits the ground, and you are touching the neutral line with your hands and the ground with your feet, would you get shocked? Also, same question, except the lines are coming out of a grounded portable generator instead of the electric company.

submersible 480v pump w/out ground! I came across a 480vac submersible pump (70hp) that was not grounded. This lead me to a question about water and electricity. If the motor lead (one of them) insulation had been damaged and the conductor came in contact with the water, what would be the...

Homework Statement Hey guys, I'm studying AS level physics at the moment in the UK and I'm having a hard time grasping the concept of the ground state of an atom, so my question is: Is the ground state the energy level that is closest to the atoms nucleus or is it the energy level that a...

Neon has lowest excited energy at 1(s^2)2(s^2)2(p^5)3(s^1) state. And the excitation energy is about 16.9eV. And next energy is at 1(s^2)2(s^2)2(p^5)3(p^1) state. And the excitation energy is about 19eV. In Franck Hertz experiment with Neon, current decrease at every 19eV, no 17eV. Why...

Homework Statement Folks, I am looking at a past exam question regarding the Harmonic Oscillator. The question ask 'Justify that the ground state of a harmonic oscillator a_\psi_0=0 equation 2.58 on page 45 of griffiths. THis was not covered in my notes. Any ideas how to justify this...

Hey all, I'm a student curently studying in a Singaporean Junior College (American 12th grade equivalent). I was curious and just thought of the following: Suppose a system with a electron and a proton nucleus, a hydrogen atom. From electrostatic force and circular motion equations- F =...

Homework Statement A two-dimensional harmonic oscillator is described by a potential of the form V(x,y) = 1/2 m \omega^{2}(x^{2}+y^{2} + \alpha (x-y)^{2} where \alpha is a positive constant. Homework Equations Find the ground-state energy of the oscillatorThe Attempt at a Solution I have tried...

Note the the projectile must rely on it's own kinetic energy after release from the projecting mechanism. Also is there a practical limit on the hight which can be achieved. No new energy given to the projectile after release. the hight of the launching apparatus does not count thus...

Hi guys, Just got a question I'm a little stuck on and would love a push in the right direction Q) Using Hartree's theory calculate the degeneracy of the ground state of the Sodium atom. Its a previous exam question and I'm struggling to find much descriptive information about the topic...

Why is everything in the electrical system in a car connected to ground, along with the battery? Is it just a convenient way to complete the circuit for everything without using many more wires?

Homework Statement An archer shoots an arrow over level ground. The arrow leaves the bow at a height of 1.50 m with an initial velocity of 79.5 m/s in a horizontal direction. At what horizontal distance (in m) does this arrow strike the ground? The answer is 44m but I don't know how to get to...

Homework Statement Explain what is the difference in terms of energy between the ground states of rigid rotors and of harmonic oscillators? Homework Equations The Attempt at a Solution All i can deduce is that because the quantum number L is equal to zero, then E(0)=0 and the...

Have to find the probability of measureing the ground-state energy of a particle. -in infinite potential well 0<x< a has wave-function \psi (x,0) = Ax(a-x) where a is the (known) length of the well, and the norm. const. A has already been found. The eigenvalues of the hamiltonian in...

I have confused myself with this by reading a combination of Wikipedia, books and my QM notes and I'm afraid I need someone to untangle me please. Basically what I want to know is, what are the consequences of the Pauli exclusion principle for the ground state of the helium atom? Here's my...

Homework Statement So to test the variational method of simple harmonic oscillator I am using some functions that can be a good approximations, such as: Gaussian: \psi(x)=Ae^{-bx^2} Polynomial: \psi(x)=1-bx^2+\frac{b^2 x^4}{2} (I just expanded the Gaussian into Taylor, I can use just...

uncertainty relation. I think I'm on the right track. Currently, I'm at, E = (1/2m)*<p^2> + (1/2)*k*<x^2> and when applying the uncertainty relation, deltax = <x^2>^(1/2) deltap = <p^2>^(1/2) How do I go about connecting everything from here? Thanks!

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?

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...

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...

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...

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...