Ground Definition and 921 Threads

H=\frac{p^2}{2m'}+V_0(r)+V(r) where V(r)=2[3\frac{(S \cdot r)^2}{r^2}-S^2] and V_0(r) is a rotationally invariant potential, p=p1-p2, the relative momentum and m' the reduced mass. S=S1+S2 spin operator. Assume first that V(r) is zero; what is the degeneracy of the ground state...

Can someone explain to me why the ground state energy of a free electron fermi gas is not just: E = 2 \int_0^{k_f} \frac{\hbar^2 k^2}{2m} 3k^2 dk Where the factor of two is due to the fact that there are two electron states for each value of k. The idea is to add up all the energies of...

Hi everyone. I am doing research for a technical analysis study, and I need a little help. What determines the amount of "bounce" an objects creates when it hits the ground? Now, this object is a perfect shape hitting a even floor, so the angle should have nothing to do with it...

A pile driven into ground using a hammer question! Hi all, I have been attempting the following question, could you check my answers /method please :) A pile is driven into the ground by a hammer of mass 500Kg's dropped from a height of 4 meters. The mass of the pile is 40Kg's and the...

The height of an object above the ground at time t is given by s = v0t - (g/2)t2 where v0 is the initial velocity and g is the acceleration due to gravity. (a) At what height is the object initially? (b) How long is the object in the air before it hits the ground? (c) When will the object...

dear friends i have a problem in physics please solve it it is that a man covers 100 m distance by running...so calculate the total time by that he was in contact with the groung and the time that the time he remain in the air... numerically d=100m t(on the ground)=? t(in the air)=...

Erik Drops a ball from a height of 15.0m above the ground. After it hits the ground it only bounces back up to a height of 13.5m. Erik Catches it at this point, as it is just about to fall back down. just need some quick helping steps to get me started on these questions help would be...

which drop of water has more "force" to hit ground? wish to know which drop of water has more "force" when hitting ground? http://img93.imageshack.us/img93/9831/image20nh.png and perhaps some "simple" explanation why you think so. thank you :)

This is my second post concerning a question I had from Hawking book. I am completely new to this subject, and lack the mathematical background necessary to fully understand these concepts, but I hope that by posting my question I will at least not be so confused about it after receiving some...

hi can anyone please help me I came across this statement "Since we only consider the electronic ground state of the system, there can be no net force or torque acting upon the subsystem of classically behaving nuclei". Can anyone explain what this means?

Occams razor and logic implies that there has never been nothing, so why back ground independance ?

What is the ground state energy of the following. (a) an electron Well the formula is: E_n = (h^2/(8*m*L^2))*n^2; The ground state means, n = 1, its the lowest enegery level possible. So i plugged in n = 1, mass of e = 9.11E-31; h = 4.136E-15 eVs; L = 100 pm, because the book says that's...

Im doing a mobile device and i want to create a floating ground but I've no idea how to do it or even if its possible. the catch is that it also functions as a excess current channel from a current limiter circuitry included. thanks for any advice.

A particle has mass 'm' and potential V(x) = x^2. Find the ground state of this wavefunction. Should I use the Hamiltonian operator here?

I need some help with this mechanics question please, A ball is thrown vertically upwards with speed 10ms/s from a point 2m above horizontal ground. a) calculate the length of time for which the ball is 3m or more above the ground. b) calculate the speed with which the ball hits the...

Hello everyone, I just started physics a few days ago (with 0 prior experience) so I'm still queasy with this stuff. If anyone could help me with this problem, I'd really appreciate it. Say I drop an object from a height z0. How long does it take the object to reach the ground? There are two...

I have this problem to do for homework for my physics class and I don't even know where to start! Could someone try to give me clues? The problem is: A pilot flies horizontally at 1300 km/h, at height h= 35 m above initially level ground. However, at time t = 0, the pilot begins to fly...

Person A: Falling from the top of a 20' ladder. Or Person B: Falling with a 20' ladder that is falling over. (from the top) Give me your answer and tell me why? This one is driving me crazy!

Hello I had a debate on comparing walking on the ground with velocity V and wlaking on an electrical walker with the same velocity V. My claim is that there is no difference between walking on the ground in velocity V and walking on an electrical walker with the same velocity V, in terms of...

My question is, derive an equation to find the maximum range of a projectile that's not on level ground. I am lost and i did attempt this, by making a diagram and subbing in what i thought i would need to use, but i still have not come up with the answer. please help

how can you measure the speed of the plane from the ground. Can anyone help and please explain as much as you can and if you can provide the equation/example that would be wonderful.?

The figure shows a bicycle wheel resting against a small step whose height is h = 0.110 m. The weight and radius of the wheel are W = 29.0 N and r = 0.350 m. A horizontal force F is applied to the axle of the wheel. As the magnitude of F increases, there comes a time when the wheel just begins...

Hi All Suppose we have a rectangular pool filled with water. But the concrete ground of this pool is substituted by a rubber sheet, resistent obviously to the weight of the water inside the pool. Now consider we produce a plane wave traveling along the greatest dimension of this rectangular...

According to a recent statement by general George Casey, senior military commander in Iraq, There is currently only one Battalion of Iraqi soldiers currently prepared to do "stand alone" operations. I find that a bit odd considering that Casey had said in June that there were three...

The paper delivery boy tries to throw the paper into your narrow driveway without slowing down. His pickup truck travels at 5.00 mph, and he throws the paper at 16.0 mph just as the truck passes the driveway. in what direction should he throw the paper in order for it to land in the driveway...

I'm a computer programmer, but I'm having trouble with this one. I need help figuring out how to calculate a 3D velocity vector which will make a projectile follow an ARC between two points on the ground, firing with a fixed speed. I have a cannon at point a (x, y, z) I have a target on...

Has anyone ever set off a really big professional-grade star burst style firework on the ground, in a desert somewhere? Maybe at the Burning Man festival? I am thinking you could stand within 30 feet of the epicenter in a plexiglass enclosure, with ear protection, and be unharmed. What...

I'm new to this site and I'd like to begin my thread posting by asking about the foundations of mathematics. The more I learn math, the less I feel I know and it is getting a little depressing. I have two semesters of college level calculus under my belt (ending the year with Taylor and...

isn't it possible for the gravitational force and the elcetrical origin forces have something very very common fundamentally to both of them

Hello! here is one question which I still donno how to solve: A thunder cloud with a large flat square base measuring 3000m x 3000m passes over an area on level ground. Assuming the cloud carries a total charge of 40C which is spread evenly over its base and is at a height of 0.5 km above the...

Hey all, I was wondering if it would be possible to make a craft that used specially designed rotors or props placed under a craft that were made to take advantage of the ground effect (ie a large surface area, endcaps on them and so on) as long as stability was taken care of by way of auto...

A ball is thrown into the air from ground level. After a time t = 1 s, the ball has traveled to a position x1 = 28 m to the right of and y1 = 13 m up from where it was thrown (at this time, the x and y components of the ball's velocity are still positive). The axes show the x and y directions to...

This name must come up frequently in this forum, but I'm sure it is mostly when discussing "The Bell Curve." Instead of discussing IQ and race I wanted to discuss the topic of Murray's 1984 book, "Losing Ground." Basically, Murray claims that welfare policy is a complete failure that...

I am rewiring my old house (35+ years old) that had non-grounded aluminum wiring (very dangerous!) with good ol' copper/grounded wiring. I have four rooms done and in each room I have put in wall outlets that go to a switch by the door. When I finished the rooms, I used my circuit tester to...

Hi, I'm stuck on this problem: Two solid hemispherical conducting electrodes each of radius r=a are pressed into the earth, curved surfaces down, such that the flat surfaces are flush with the (flat) Earth's surface. Assume that the electrode separation (center to center) is d where d >> a...

Will boiling ground water that contains sulfur produce a yellow sulfur residue. Thanks, --Keith

If we calculate the ground state energy of a system we receive E=w*h(bar). This Energy can be derived with the harmonic oscillator. Is this Energy the Energy of a free photon or a free electron in (for ecample) the vacuum state or is this describing a particle between (potential,...) walls...

1. Why do tires grip the road better on level ground than they do going uphill or downhill? I have some ideas, but I'm not sure how to word them, or if they are correct. Any suggestions would be appreciated. 2. A mass M(1) = 3.5 kg, rests on a horizontal table and is attached by ropes to...

a wooden peg is hit vertically by a mallet which is also moving vertically. The mass of the peck is 0.4kg and the mallet is 2kg. The speed at which the peg starts to move into the ground is 6.67m/s. Given that the ground opposes the motion of the peck with a force of 1kN, find how far the peg is...

When doing L-S coupling scheme for (3d)4, I am asked to find the ground state. I know that the first step, according to Hund's rules, is to find the the S with the largest value (S, L are total values, s, l are individual values). It is obviously S=2. Next, I should proceed to find the largest...

Hi, I am new here, and am not expecting any direct answers (I read the sticky) but I am pretty confused about this one question: A ball is shot vertically upwards at 10m/s from a height of 5m above the ground, If friction can be ignored, what is the speed of the ball immediately before it...

Can someone please explain to me why the time it takes for an object to drop down is the same time it takes to hit the ground if you throw it? Thanks

Has anyone read Gravitation from the Ground Up, B.F. Schutz? What did you think of it? Pete

I asked this question in another thread, but wonder about the answer I got: Question: I bought an atomic-timed clock and wondered if while I am taking off from an airport my clock would record time slower than a clock inside the airport. Since time on the clock is actually maintained by a...

anyone happen to know how to estimate the ground state energy of a vee-box using the uncertainty principle?

Hi - Here's the entire problem to avoid confusion >< "A kite is flying at a height of 500 ft and at a horizontal distance of 100 ft from the stringholder on the ground. The kite string weighs 1/16 oz/ft and is hanging in the shape of the parabola y=(x^2)/20 that joins the stringholder at...

What is the most probable value of r for the grounds tate of hydrogen, and why? Is it just the Bohr radius?

I don't actually have a specific homework question, but I'm wondering if anyone could explain to me how you solve a stopping distance problem. I've encountered these questions in very different ways, once with very little information given, and one with a considerable amount of calculating to...

HELP! plase! help I can't figure out what to do with this assiment that I have this is a sample question. A boy standing in a ditch throws a baseball upward toward his father. The ball leaves his hand at ground level, with an initial speed of 14.0 m/s, at an angle of theta = 59.0 degrees...

This seems like an easy problem but without "time" i"m confused. The best leaper is a Puma that can jump to a height of 12 feet when leaving the ground at a 45 degree angle. With what speed in SI units must the Puma leave the ground to reach this height? I'm not sure what formula to apply...