Ground Definition and 945 Threads

Ok so I'm in 7th grade and I think I'm pretty good in science class. The other day we had some math questions involving some equations. One question was something like a spaceship hit the ground with a velocity of 100 m/s and then it asked like what was its mass. This question also included...

Earlier today, I just took the last examination paper for my examination in my third year in computer engineering. (One more year left to go.) Over the past year, now that I no longer have to do mathematics as a subject forced down my throat - it was a compulsory subject until the end of the...

I am having a little confusion about the difference between neutral and ground because certainly one can touch a neutral wire and never get a shock. What is neutral any way is it neutral, 0 volts. Then while handling electronics we only use DC. Now in DC there are 3 things 1.Positive(+) or...

Why a spinning top won't fall to the ground? yes I know this question must have been asked before right? tried looking for it on here but I couldn't find it.

Hi all, One of my guys was working on a control ciruit for a fan bank. The control circuit in powered by a 480-120 V control xfmr. His voltages from x1-x2 were 123 Vac. Across all energized relays: 123 Vac. But when he took voltages to ground he got around 40 Vac from the X1 bus to ground...

Hello, Non-relativistic quantum mechanics doesn't explain why the electron in the hydrogen atom (for example) "decays" from excited states to the ground state. Which theory does explain this phenomenon (from basic principles) ? Thanks.

Hey, I was looking at a car and the dealer told me the battery is at the back in the trunk. When he opened the hood he showed me how I would jump it if needed or anything else. He said there is one rod (that was visible coming through a connection from the battery) for the positive and for the...

Short Circuit Current Hi, I am reviewing a ground grid study of a substation for a wind farm that is being built. The ground grid will be for a substation with a low side of 34.5kV and two transformers that step the high side voltage up to 345kV. There are six distribution feeders on the...

Homework Statement The particle in a box model is often used to make rough estimates of ground state energies. Suppose that you have a neutron confined to a one-dimensional box of length equal say 1 x 10^-14m. What is the ground state energy of the confined neutron? answer in MeV...

I jump off a high bench (5ft high) to the ground. What is the g-force of the impact and how do you calculate it. It seems mass is irrelevant for this Joe

Hi, I am new here and have a couple questions. First, If someone is standing in their house on a carpeted floor with rubber soled shoes on and they only touch the hot wire, will they get a shock? Also, can anyone explain how those pen voltage detectors work where you only have to touch one...

Homework Statement an electron moves in 1D and is confined to the right half (x>0) potential: V(x) = -(e^2)/(8piEx) E is the permittivity of free space the ground state wave function is Nxe^(-ax) N is normalization constant, and a is another constant needed to be determined Homework...

Homework Statement I got struck with this problem again in the review questions and still can't do it, I think this problem shows a major gap in my knowledge of the subject. A solid ball of radius R is set spinning with angular speed \omega about a horizontal axis. The ball is then...

Pretty simple question that I was curious about earlier today. If I were to drop a bullet from the same height and at the same time as my friend shot the bullet from a gun, would they hit the ground at the same time? I think that they would considering the bullets frame of reference it is at...

Is the ground state of any negative potential that goes to zero at + or - infinity always even?

Homework Statement A spool of thread comprises a cylinder of radius R1 and is capped with two disks of radius R2, where R2 > R1. Some thread is tightly wound over the cylinder. The whole spool is laid stationary, side down on the ground and the thread is pulled. The spool rolls without...

Hi everyone! First post here, seems like a great community. Anyways, I'm having a bit of trouble. (I missed a bit of classes due to illness, and I'm a bit behind.) Here's the problem: You stand on top of a building 9.50 meters high, and throw a ball almost straight up. The ball is...

Homework Statement using first-order perturbation theory ,estimate the correction to the ground state energy of a hydrogenic atom due to the finite size of the nucleus, assume it's spherical nucleus. Homework Equations you can employ the fact that the electrostatic potential fi...

Homework Statement A plane is heading due east and climbing at he rate of 80kph. if its speed is 480kph and there's a wind blowing 100kph to the northeast, wha is the groundspeed of the plane Homework Equations The Attempt at a Solution w=100cos45+100sin45= 70i+70j...

Homework Statement A solid ball of mass M and radius R is spinning with angular velocity \omega_0 about a horizontal axis. It drops vertically onto a surface where the coefficient of kinetic friction with the ball is \mu_k. Find an expression for the final angular velocity once it has...

How many magnetic flux quanta exist within the ground state hydrogen atom? Thanks in advance.

Hi all: As we know, if we solve the schrodinger equation, the ground state wavefunction is independent of theta and psi. We find the expectation value of ground state orbital angular momentum is zero. But if we don't do any mathematical calculation, can we conlude that? For example, Due to...

Hi, I'm a bit confused on how ground tracks for satellite work. I have noticed they orbit the Earth with a ground track that oscillates all around. Why is this? And why does the oscillation change in latitude for every pass around the earth. Thanks. Much appreciated.

In QM, sometimes we will combine the delta potential and other familiar potential (like infinite potential well). And I am quite confuse with the bound state. For example, consider a 1D infinite potential well with width a and locate b/w [-a/2, a/2]. Now if we add in a delta potential...

If I know the explicit form of potential, the energy and a specific eigenstate, but I don't know the general form of eigenstates and eigenvalues, can I tell if the state is ground state or not?

Homework Statement Hi all. If a system will settle into a state where the entropy is at a maximum, then why is it that the electrons in an atom will always settle for the lowest energy state, and not have an equal propability of being in either state? Is it because the entropy of the...

What regulates the ground state energy of a hydrogen atom? Why is it constant (more or less)?

Homework Statement How does a parachute help a man hit the ground with a small kinetic energy? Where does the energy go? Explain everything in energy terms. Homework Equations The Attempt at a Solution i think that when the parachute is deployed, the kinetic energy the man has...

Hi, I am trying to work out the ground run distance of takeoff for an aircraft. I can't really write the formula down because of the length and many variations of it so I am just hoping that you know what I am talking about. I am trying to work it out for a cessna 172 so i am expecting a...

Homework Statement Calculate the energy of the electron in the ground state of triple ionized beryllium, which has an atomic number Z = 4. Homework Equations -Z2 (13.6) N2 The Attempt at a Solution Z=4 as given and it is tripled so our N=3. We throw our numbers in...

Homework Statement See post #3 Assume the YoYo is a solid cylinder with mass M and radius R for all parts! Homework Equations Lots? The Attempt at a Solution Part A - Find the moment of inertia about the center of mass and the point of contact with the ground: ICOM = 1/2 MR2 IIPoC = 1/2...

Homework Statement Consider a Hydrogen atom in the ground state Find: A- The Kinetic Energy, in eV B - The Potential Energy, in eV C - The Total Energy, in eV D - minimum energy required to remove the electron completely from the atom, in eV E - What wavelength does a photon with the...

Homework Statement Al3+ N3- Li+ Au+ Sr2+ Mn2+ Tl+ Br - Homework Equations The Attempt at a Solution no clue, the positives and negatives are messing me up

Hi all. I'm working on an RF system including a 2.4G transceiver and a GPS receiver. I'll use a ground plane. What I intend to is to separate analog ground and digital ground and connect them together at the entry via a 0ohm resistor. My friend argues that a whole ground layer that connect to...

Homework Statement What are the energies of the ground state and the first two excited states of the He+ ion? Homework Equations En= - Eo/n2 The Attempt at a Solution n=1 for this problem (since there is only 1 electron) so the ground state would have the electron...

I'm building a tank circuit and I need to know if a ground connection is needed.

Homework Statement A model rocket releases its first stage when it is 100.0 m above the ground and moving upward at 40.0 m/s. Ignoring air resistance, find: the time it takes the first stage to hit the ground Homework Equations Y=Yo+VyoT+1/2GT^2 Quadratic The Attempt at a...

Homework Statement I just want to know if there is a relationship between the ground state of Hydrogen which is 13.6 eV and the ground state of Helium. The problem is asking me to find the ground state of Helium, but I am not sure how to go about it. Any advice? Homework Equations...

Homework Statement A hellicopter traveling upward at 69 m/s drops a package from a height of 500 meters. To the nearest second how long does it take to hit the ground? Homework Equations possibly displacement?? v= 69 x=500 a=9.8 t=?? The Attempt at a Solution do i use X=1/2...

Homework Statement I have been given the Hamiltonian H = \sum_{k} (\epsilon_k - \mu) c^{\dag} c_k where c_k and c^{\dag}_k are fermion annihilation and creation operators respectively. I need to calculate the ground state, the energy of the ground state E_0 and the derivative...

How does one calculate the distance (or length) on the ground suspended by one minute of arc (or one second of arc) at a particular point on the Earth's surface,given its latitude/longitude in degrees/ minutes /seconds ?.Where would one get the Earth radius of sufficient accuracy as a function...

Prove that the flange of a train wheel moves backwards in respect to the ground, using the trigonometric functions, linear and angular velocity I really have no idea to go about doing this, all I know is that the proof involves some use of trigonometric functions, linear and angular velocity

Hey, I'm currently in a physics class (im not real good at it hah). And a lot of times out of class i think and relate things to what I have learned... Well, me and some friends were talking about tasers, and I was wondering if it were possible for multiple people to connect (hold hands...

This is what I've tried to work out and I'm not getting -13.7 eV. What am I doing wrong? E 2 Π m e^4 / (4 Π ε0 )^2 h^2 6.90E-19 J=4.31eV m 9.11 x 10-31 kg 9.11E-31 e 1.60 x 10-19 C 1.60E-19 ε0 8.85 x 10-12 C2/Nm2 8.85E-12 h 6.63 x 10-34 J S...

[b]1. Homework Statement [/ What happens to the kinetic energy of a projectile when it hits the ground Homework Equations The Attempt at a Solution

Homework Statement King Arthur's knights fire a cannon from the top of the castle wall. The cannonball is fired at a speed of 45m/s and an angle of 32degrees . A cannonball that was accidentally dropped hits the moat below in 1.4s . a) How far from the castle wall does the cannonball hit...

Homework Statement Seven electrons are trapped in a one dimensional infinite square well of length L. What is the ground state energy of this system as a multiple of h2 / 8mL2?Homework Equations Energy of a single electron in state n is n2h2 / 8mL2The Attempt at a Solution Pauli exclusion...

While driving North at 25 m/s during a rainstorm you notice that the rain makes an angle of 38 degrees with the vertical. while driving back home moments later at the same speed but in the opposite direction, you see that the rain is falling straight down. From these observations, determine the...

Homework Statement A 35.5 kg parachutist lands moving straight downward with a speed of 3.85 m/s. (a) If the parachutist comes to rest with constant acceleration over a distance of 0.700 m, what force does the ground exerts on her? Variables: Vo, Vf, F, m, a, x Known: Vo=3.85 (I think the...

Homework Statement From serway's book chapter 23(electric fields), questions section. Homework Equations --- The Attempt at a Solution The obvious answer would be that it is safe because the student holding the sphere is insulated from the ground, but what does that really mean ? If I try to...