Ground Definition and 945 Threads

Homework Statement An object is thrown with speed 20 m/Sunder the angle pi/3 rad with the horisontal direction. In the highest point, the object is divised into two pieces with same weights. One of them, after the division has the speed 0. How far from the starting point do the pieces fall on...

Homework Statement Estimate the ground state energy (eV) for an exciton in Si. εSi = 12 ε = 1.0359×10−10 Effective masses me* = 0.26me mh* = 0.36me effective mass = 0.15me Values of h 6.626×10−34 J⋅s 4.136×10−15 eV⋅s Values of ħ Units 1.055×10−34 J⋅s 6.582×10−16 eV⋅s Homework Equations E1 =...

A stationary object resting upon the ground experiences two forces, the weight force as well as the normal reaction force of the ground. These forces sum to zero. The ground however experiences the weight force acting downwards upon it. What other force acts upon the ground to prevent it from...

Hi, given an Hydraulic Cylinder with the Formula: F=p*A Why do we use APiston to calculate the Force in Work-Direction? Doesnt it suppose the "Potential Energy" of the compressed air just presses in that Area? Im pretty confused, sorry about the unconcrete question.

Homework Statement A hot air balloon is ascending straight up at a constant speed of 7 m/s. When the balloon is 12 m above the ground, a gun fires a pellet straight up from ground level with an initial speed of 30 m/s. Along the paths of the balloon and the pellet there are two places where...

Hi. If an electrically neutral, conducting rod is brought close to a (say negatively) charged object with one end, charges will separate due to electrostatic induction roughly as follows: Let's now connect the rod to the (far-away) ground with a long cable. Does it make a difference whether...

Homework Statement a. Find the voltages Va, Vb, and Vc. b. Find the currents I1 and I2. Homework Equations Ohm's Law, Current Divider The Attempt at a Solution [/B] My first attempt was to redraw the circuit. I know that these voltages are with respect to ground. Therefore Va to Ground is...

Homework Statement On a long bus ride, you walk from your seat to the back of the bus to use the restroom. The bus is driving at 120 km/h , and you walk at 2.5 m/s from your seat to the restroom. How quickly are you moving relative to the ground? Homework Equations vpg=vpb+vbg The Attempt at a...

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 58.0 m away, making a 3.00° angle with...

Homework Statement A person jumps from the roof of a house 3.9-m high. When he strikes the ground below, he bends his knees so that his torso decelerates over an approximate distance of .70m. If the mass of his torso (excluding legs) is 42 kg, find a. his velocity just before his feet strike...

1. problem: a body of mass started to fall from rest, and from S elevation. what is the equation that calculate the force of what this body will hit the ground? Homework Equations :[/B] F=mg // which is used to calculate the force of the body on the ground when it is already on the ground...

Homework Statement [/B] P=60kN angle alpha = 45 degrees angle beta = 20 degrees The task is to calculate the force on the base A and C, and to draw vectors that represent those forces. Homework EquationsThe Attempt at a Solution I did similar examples at the class, but when I had to do this...

Homework Statement A helicopter is flying in a straight line over a level field at a constant speed of 6.8 m/s and at a constant altitude of 9.4 m. A package is ejected horizontally from the helicopter with an initial velocity of 12.0 m/s relative to the helicopter, and in a direction opposite...

I have a questions about AC and DC components being grounded to the same spot. I have a power supply box that takes in 120V AC and brings that into a transformer that converts it to 24V DC. On the way into the box the ground wire from the 120V AC is brought into a grounding terminal block and...

Homework Statement A ball is shot from the ground into the air. At a height of 8.8 m, the velocity is observed to be v = (7.4)i + (5.7)j in meters per second (i horizontal, j upward). To what maximum height will the ball rise? Homework Equations V^2 = Vi^2 + 2a(Δy) The Attempt at a Solution...

I used to have a bunch of these on - ahem VHS,,, This was one that I think shows - all bets are off on trying to predict ground fault current... Even the firemen, keeping their distance (not enough IMO), are almost fooled as the arc stops around 1:42.. nope.

Hello. I'm now taking accelerator physics class and the lectures said in the thermionic electron gun, anode metal mesh should be grounded in order to prevent electrons which traveled beyond the mesh from coming back due to the electric field lines. Without grounding of the anode, I believe...

Homework Statement Force exerted by the ground on the rocket Mass of the Rocket = 1500kg Duration of landing impact = 0.04 s Velocity at time of impact = 175 m/s Distance traveled = 30km Time taken to complete journey = 6 minutes Acceleration due to gravity = 9.8 m/s^2 Homework Equations...

Hi. Assume we connect both plates of a capacitor to ground and disconnect again, leaving them at ground potential. Then we bring electrons from one plate to the other, until there is a voltage difference ##\Delta U## between the plates. Compared to ground, one plate has the potential...

Does it really mean the Earth or exceedingly large bodies like the ocean are useful sources of charge? What would happen if you built a very large Van De Graaff generator under the ocean? If the capacitance of the Earth is only 710 µF, could we infact measure a rise in potential at distances...

First of all , I'm a completely new to this current - voltage concept , I have problems understanding Grounding and the current flow in circuits . 1) Which path do currents take when there are multiple grounds in a circuit . 2) How and where should a circuit be grounded and why ? 3) Why is...

I suspect it has a very noisy pick up from back ground gravitational radiation, what source is the most likely candidate for this back ground radiation?

Second attempt on land today, second success: A Falcon 9 delivered a Dragon capsule on its way to the ISS, and the first stage returned to the launch site and landed. Track record for the "Full Thrust" version so far: 2 out of 2 landings on ground successful 3 out of 5 landings on sea...

Homework Statement I attatched my question as a picture Homework EquationsThe Attempt at a Solution 1.i found a solution using kirchhoff law, V1=-11V,V2=-9V and it was correct. but i`m not sure that my method was right. i know that kirchhoff law is originated from charge and energy...

There is a cathode to ground resistor on a KT66 power tube on a amp kit. The value is 1 ohm. I ASSUME the only reason for it being there would be to be able to measure the current flow. I ASSUME 1 ohm is not going to change the cathode bias. Is my assumption correct? The KT66 is a beam power...

Hello there, I know this may seem basic physics but I would be interested in how to calculate various things concerning force output on the ground when I, a machine or an object pushes another. A few examples, a machine, let's say a large digger sort of contraption is pushing 100 tons of metal...

I have drawn my circuit in Proteus, and in the simulation it can run, but when i used GL 12 test board to test my circuit, it can't run. And i reallize that i don't know where is the ground in the test board. Can you guy tell me where is the ground ?

Do all electrons orbit in the ground state, when the band gap, is increased, or decreased, as atoms come together to form molecules.? Like in glass, transparent liquids, and plastics. As atoms come together to form glass, like silicon, sodium, and calcium. Do the electrons orbital permanently...

Homework Statement A projectile is fired over level ground with an initial velocity that has a vertical component of 20 m/s and a horizontal component of 30 m/s. Using g = 10 m/s2, the distance from launching to landing points is: Homework Equations Vi(t) +0.5at^2 The Attempt at a Solution I...

I launched a model rocket, and like a dummy, put the nose cone on too tight. From its apogee (aproximately 1000 ft.) it fell to Earth at a terminal velocity of 31 mph. It ran into firmly packed dirt and no rocks. I want to know how many Gs the rocket was under when it hit the ground and if it's...

Homework Statement A block exerts a pressure on the ground. If the block is split vertically into two halves does the total pressure on the ground increase, decrease or remain the same? Homework Equations Pressure = Force/Area The Attempt at a Solution I think that it doubles but I am not...

Several heads on my irrigation system are leaking when my irrigation pump cuts off. The irrigation pump is 30 ft lower in elevation than the bottom of the 1200 gallon water tank that supplies water to the pump. I keep about 4 feet of water in the tank, so the pump is essentially 34 ft below...

Hey guys, recently I have do some self-study on the ground response parameters on cohesive and cohesionless soil.. I made some deduction but I cannot confirm if it is correct or not, thus needing the help from the PF community. The deduction is as follows; I need explanation for the occurrence...

Homework Statement Consider a quantum particle of mass m in one dimension in an infinite potential well , i.e V(x) = 0 for -a/2 < x < a/2 , and V(x) =∞ for |x| ≥ a/2 . A small perturbation V'(x) =2ε|x|/a , is added. The change in the ground state energy to O(ε) is: Homework Equations The...

OK, so I've gone through probably 90 tutorials on electricity and related topics, and there's a bundle of terms I ran into, used by people ages 12-80 with a dozen different accents and twice as many time zones. (So I'm not sure how many terms are universal and how many are provincial). Live...

Hi, may I request help or quick review to ensure that I present an accurate understanding of this concept. I want to move begin learning about the free fall of one block onto another block, but would like to be sure that I understand the physics of work, force, and energy of one block. Thank...

Homework Statement Is sky wave signal less stable than ground wave signal? Homework Equations None The Attempt at a Solution Ground waves face attenuation because when it glides over the surface of earth, there will be induced fields which can oppose the wave. In case of sky waves, it...

The situation: I have one BMS (Building Management System) controller supplied from TR1 (220Vac to 24Vac transformer) and provides an analog control signal (0-10VDC) with the (-) of that DC being the same as the Neutral of the controller (from TR1) and should control a valve actuator. The...

Homework Statement I have seen Earth and ground used interchangeably. However, there appears to be some distinction with regards to reference point ground and Earth ground. My textbook used an example of a loaded voltage divider and examined how the voltage across certain resistors can be...

Homework Statement "A ball of moist clay falls 15.0 m to the ground. It is in contact with the ground for 20.0 ms before stopping. (a) What is the magnitude of the average acceleration of the ball during the time it is in contact with the ground? (Treat the ball as a particle.) (b) Is the...

Currently working through a chapter on op amp circuits, fundamentals. Came upon this practice problem in the section on inverting op amps imgur link: http://i.imgur.com/2DrQLXk.png imgur link: http://i.imgur.com/7KRKzKC.png A working of this problem is not given. I got the correct answer...

Homework Statement A boy and a girl both swim at 3.0m/s. They jump into a river 1.0km wide, with a current of 2.0m/s[E]. a.) The girl swims so that she ends up directly across from her starting point. What is her velocity relative to the ground? Homework Equations Note: V = velocity with...

I was wondering how to approach building a bridge which must lie across to points of differing points (one end is elevated 5 cm off the ground), meaning the bridge lies at an angle across a 35cm expanse. How would you calculate the forces exerted on each member if the bridge does not lie...

What do you think about Feynman's description (http://feynmanlectures.caltech.edu/III_12.html#Ch12-S3) ? It seems to be inconsistent with hyperphysics (http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/h21.html).

I'm trying to setup a hobbyist electronic bench in the garage. What is the best way to setup ground.

How to compare the ground state energies if diagrams containing x vs V are given. I saw a problem containing diagrams three potentials and they have asked to arrange them in order of their ground state energies. One was a potential well, and the other two had small perturbation in the middle...

I have the solution for this problem but don't understand it. 1. Homework Statement Use Hund's rules to calculate the ground state of erbium with electron configuration [Xe]4f126s2 Homework Equations Hunds Rules: 1. Maximise S (within Pauli) 2. Maximise L (within Pauli) 3. Min J (for...

For hydrogen atom ground state we know φ=π-1/2a-3/2e-r/1 I want to know the complex conjugate of φ* ?

Homework Statement Brick is sliding off a roof, starts at the peak of the roof (7.0 m above ground), slides down roof with kinetic friction value of 0.28, very edge of roof is 4.0 m above ground. Where does the brick land on the ground? Please see image - http://imgur.com/wNdtlWD Homework...

OK, sounds nutty in a limited short title, but... For a planned dome home in an area where average annual air temperature is 72 degrees, and thus steady state ground temperature at 20' deep or so stays within a pretty narrow range near that 72 degrees year round average above, and where house...