Ground Definition and 921 Threads

Hey, I'm having a big problem with my master's (MSci) project, in the sense that there isn't one! My supervisor doesn't actually know what he's going to arrange as a project yet and its been a month into it, and he doesn't seem to offer any helpful insight. He keeps asking if I have any ideas...

Homework Statement A puck is sliding on flat ground with initial speed to 4 m/s and comes to rest after 2 s. Aprox. which is the coefficent of kinetic friction between puck and ground. 0.9 0.6 0.5 0.4 0.2 I don't know how to solve for this. I ended up in this class accidently and never took...

If you fall off of a chair you don't get hurt, however, if you fall off of a building you die. How is this possible if you are experiencing the same force.. F=mg

<< Mentor Note -- There is good information about shock hazards in this thread, and explanations about why some situations may not present a shock hazard compared to other situations that do. Please keep in mind that if you do not know much about electricity, you should always consider AC Mains...

I am looking over my notes for quantum mechanics, particularly for electronic state classification for nitrogen. At ground state, nitrogen atom's 1s and 2s shells are fully filled and the 2p shell is half filled, thus the configuration is: ##2s^2 2p^3## There are 3 different angular momentum...

I am trying to perform the operation a on a translated Gaussian, ie. the ground state of the simple harmonic oscillator (for which the ground state eigenfunction is e^-((x/xNot)^2). First, I was able to confirm just fine that a acting on phi-ground(x) = 0. But when translating by xNot, so a...

Homework Statement a particle of mass m moves in 1D potential V(x),which vanishes at infinity. Ground state eigenfunction is ψ(x) = A sech(λx), A and λ are constants. find the ground state energy eigenvalue of this system. ans: -ħ^2*λ^2/2m Homework Equations <H> =E, H = Hamiltonian. p=...

Homework Statement Calculate the average potential and kinetic energies for the electron in the ground state of hydrogen. Homework EquationsThe Attempt at a Solution I know that KE = E - <U(r)>. I know that E = (-KZ^2e^2)/(2a0) and I know that U(r) = -KZe^2/r but I can't figure out how to...

A ball is thrown straight up from ground level. After a time 6.1 s, it passes a height of 136.1 m. What was its initial speed? The accelera- tion due to gravity is 9.8 m/s2 . Answer in units of m/s. Homework EquationsThe Attempt at a Solution

Using the single-electron wave function ψ(r) = N*exp( −ζr2 ) with ζ a variational parameter, how can we calculate the best approximation for the ground state energy of the hydrogen atom?

Homework Statement Just before hitting the ground, a partially inflated 0.625kg basketball has a speed of 3.30m/s. Then it loses half of its kinetic energy as it bounces. (A)What is the ball's speed immediately after it bounces?(B) If the ball is in contact with the ground for 9.25ms, what is...

Homework Statement A uniform ladder which is 10 m long and weights 300 N leans with its upper end against a smooth vertical wall and its lower end on rough horizontal ground. The bottom of the ladder is 6 m from the base of the wall. A man weighting 700 N stands on the ladder at a point 6 m...

A jet flying directly over you at an altitude of 3300 m produces a shock wave. The angle of the shock wave is 43 degrees. How long will it be until the sonic boom reaches you? How far does the jet travel during this time interval? I know that I can figure out the second part of this problem if...

Homework Statement A ball is thrown from the edge of a 10.0 m high cliff with a speed of 20.0 m/s at an angle of 30 degrees below horizontal. What is the speed of the ball when its hits the ground below the cliff? Options : 1) 26.3 m/s 2) 28.1 m/s 3) 31.4 m/s 4) 24.4 m/s 5) 29.5 m/s I am new...

Homework Statement A small rock is thrown upward with a speed of 30ft/s from the edge of a building 200ft above the ground. What is the speed of the rock when it hits the ground? Use acceleration due to gravity as –32ft/s squared. Homework Equations integral of acceleration= v(t) integral of...

A check my work question... Homework Statement Louis de Broglie tried to explain Bohr’s hydrogen atom electron orbits as being circles of just the right circumference such that an electron of the Bohr energy going around the circle will interfere constructively with itself. This seems to...

Homework Statement The compass in a plane indicates that the plane is pointed due east; its air speed indicator reads 212 km/hr. There is a steady wind blowing from the north with a speed of 60.0 km/hr. What is the speed of the plane with respect to the ground? Homework Equations...

Hello, i have a really annoiyng problem , i have a robot which is equipped with a video camera(PAL) so nothing too fancy, the information is transmitted through a coaxial cable about 200 m of cables,the attenuation of high frequency is not to big to cause any problems,also the robot has some...

I know that when we have to identify the nodes for solving a circuit with nodal analysis we always have to designate a reference node (which will be the ground node) as a reference for measuring the others' voltages. However I was practicing this and I found this example on...

Hi, I was wondering whether anyone can help with a question I have about the forces acting on a car wheel and the forces the wheel induces on the ground surface. The way I understand it, a car wheel traveling on a flat surface has the following forces acting on it: -vertical force due to the...

Homework Statement Standing on the roof of a 66 m tall building, you throw a ball straight up with an initial speed of 12.5 m/s. If the ball misses the building on the way down, how long will it take from you threw the ball until it lands on the ground below? Give your answer in seconds and...

Homework Statement The problem (5.9) and given data is attached. Homework Equations All relevant equations are given (5.9). On (5.9) What does the s subscript y represent? And why does gravity equal -32? The Attempt at a Solution The solution is given. This is a scan problem.

Homework Statement A pilot flies horizontally at 1300 km/h, at height h = 76 m above initially level ground. However, at time t = 0, the pilot begins to fly over ground sloping upward at angle θ = 7.5° (see the figure). If the pilot does not change the airplane's heading, at what time t does...

Hello. Please see the attached image first. 1. The textbook seems say resistor to + input in this image is necessary to provide a return path to ground. I completely don't understand even what it mean. Could you help me to clarify this? 2. Instead of understanding directly what the book said...

Take some high voltage power line. Place a conductor between the wire and Earth ground. Current goes to ground. Why? I understand what is voltage, resistor, circuit etc. I do know that the wire is at a higher voltage than the ground. But isn't Earth also a kind of huge resistor? Thus preventing...

Hello Forum, If we connect one of the terminals of an AC voltage source to ground, the earthed terminal will maintain the same electric potential as planet earth. Earth can be assumed to be a huge spherical conductor whose electric potential does not change (much) when connected to a...

Hello all, The root problem is that I can't put all my analogue inputs onto one input card (each card has 4 inputs) on the project I'm working on. We have four sensors, they should all output 4-20mA. Two are source type outputs, supply voltage goes in, sensor current comes out, current is...

Can you please explain the difference between ground state and stationary state? In the stationary state, are the electrons at rest inside the atom?

Homework Statement A ball weighing 10g hit s ahard surface vertically with a speed of 5m/s and rebounds with the same speed.The ball remains in contact with the surface for 0.01 sec. The average force exerteed by the surface on the ball is :a) 100N b)10N c)1N d) 0.1N Homework...

< Mentor Note -- thread moved to HH from the technical chemistry forum, so no HH Template is shown >[/color] I need someone to check my answers and help me with the questions I couldn't answer. What is the max. # of electrons located in the groud state of a) an orbital 2 b) d sublevel 10 c)...

Homework Statement 1. Find the power dissipated by 12 ohm resistor 2. What is the potential at points a,b,c,d? Homework Equations P=I^2R I=V/R The Attempt at a Solution For a) 3v-IR-6v-IR=0 9v=I(18) I=0.5 P=0.5^2 * 12 = 3 watts But not sure if the ground changes anything b) unsure if ground...

Homework Statement A disk of radius R and mass m rotates on a floor with coefficient of friction μ and makes a circle of radius r0 at constant speed v0. What is the friction force between the disk and the floor. What's the inclination angle α to the vertical. It's suggested in the question to...

Hello. The ground plane is sometimes used as current return path. If current is low frequency and amplitude is small then voltage rising due to current flow can be ignorable. However, what is return current is actually very high in both frequency and amplitude? In our lab, gas discharge...

Which energy gamma rays would significantly activate ground and buildings? The most sensitive stable isotopes for photonuclear reactions are Be-9 and D. The reactions are Be-9+hnu->2*alpha+n, threshold 1,67 MeV, followed in air by N-14+n->C-14+p where C-14 is radioactive, and d+hnu->p+n...

Homework Statement Assume a particle is in the ground state of an infinite square well of length L. If the walls of the well increase symmetrically such that the length of the well is now 2L WITHOUT disturbing the state of the system, what is the probability that a measurement would yield the...

Homework Statement In the figure, a baseball is hit at a height h = 1.30 m and then caught at the same height. It travels alongside a wall, moving up past the top of the wall 1.1 s after it is hit and then down past the top of the wall 3.9 s later, at distance D = 42 m farther along the wall...

Homework Statement A ball A is thrown upward to a height H with a velocity of 20m/s, another ball B is thrown down from H with a velocity of 20m/s and a third ball C is just dropped from the same height. Find which ball has the maximum velocity when it hits the ground.Homework Equations...

Here's a physics question that's been giving me trouble. At a height H ,a ball A is thrown upward with a velocity of 20m/s and another B one is thrown down with a velocity of 20m/s and a third ball C is just dropped. Note that it's the same height for all three.I need to find the relation...

Homework Statement An athlete executing a long jump leaves the ground at a 29.5∘ angle and travels 7.69m . A- What was the take off speed? B- If this speed were increased by just 4.0%, how much longer would the jump be? Homework Equations - Unfortunately I'm totally stuck and I'm not sure...

With laser pointers being so ubiquitous, everyone is familiar with the sight of interference patterns on paper, ground glass and other surfaces (not to mention more subtle experiments like this one): Quantum Eraser -- which has been discussed recently in other threads. We take it for granted...

Homework Statement Homework Equations $$ \psi_{100} = \frac {1}{\sqrt{\pi a^{3}}} e^{-r/a} $$ The Attempt at a Solution a) $$\langle r \rangle = \frac {1}{\pi a^{3}} \int_0^{2 \pi} d \phi \int_{0}^\pi d \theta \int_0^{\infty} r^{3} e^{-2r/a} dr$$ This comes out to be ##\frac {3}{2}a##...

Homework Statement I am working through a time independent perturbation problem and I am calculating the first order correction to the energy, and I am stuck operating the perturbation : v = i b (Exp[i g x]-Exp[-i g x]) on the ground state |0>. Homework Equations <0| v |0> = 1st order...

I am looking for the rule of thumb when selecting a wire gage for ground wires on electrical circuits. Currently we use 18 GA for all of circuitry regardless of the amperage of the circuit-from less than 1A to over 30A we use 18 GA. We have never had an issue but I am wondering why 18 GA was...

I wondered about possibility of using ground effect by blended wing body, turboprop planes. Purposes: -to save fuel (for example for flying tankers); -to return partially damaged plane; -to hide under radar and become visible for ships in the last moment; -to allow flight of overloaded plane...

I have a question. If a put a marble at the top of a ramp, will the angle that ramp makes with the horizontal affect the velocity of the marble when it arrives at the bottom of the ramp? I am suspecting no, since the gravitation potential energy does not change as we change the angle of the...

Why we use the symbol ground in electronic circuits? What is the use of grounding

Hello, What shape has the lowest drag coefficient at ground level and at subsonic speeds (0-150kph) with the following dimensions? Width 60cm (at 45%) Height 120cm (at 45%) Length 220cm These dimensions will fit my motorcycle (not too narrow and not too long). I am thinking it would be a...

I work on a ship, and we have a 440V ungrounded distribution system. We have load centers that have transformers bumping that 440V down to 120V for recepticles and other services. This standard ship setup always has ground fault detection on the 440V side (at the switchboards) and at each...

1. Homework Statement A ladder on the rough floor is leaning against a vertical rough wall. The ladder has length l and mass m. The coefficients of friction are μ for both contact surfaces. What is the smallest angle between the ladder and the floor? Homework Equations ∑F=ma ∑τ = F⊥ r fs ≤ μsN...

I know how to go from ground frame to centre of mass frame by subtracting velocity of centre of mass from the bodies.But I am not sure about how to go from centre of mass to ground frame.I think we should add velocity of centre o f mass.Right?