Energies Definition and 314 Threads

Due to the blogs being removed, I thought it might be worthwhile posting a few in the forums-The Large Hadron Collider has produced collisions at 7 TeV. For collisions at 7 TeV, protons need to be ‘ramped’ to 3.5 TeV, the proton has a mass of 1.6726e−27 kg which, according to mass–energy...

Hi All, I just have a question regarding potential energies. Say I have a block above a spring, and I define the potential energy of gravity and the spring to be zero at the uncompressed point. I then drop the block, trying to find the maximum compression of the spring using conservation of...

Homework Statement An object with kinetic energy K explodes into two pieces, each of which moves with twice the speed of the original object. Compare the internal and center-of-mass energies after the explosion. The Attempt at a Solution Let K1 be the kinetic energy of the main...

Homework Statement Effective potential of atoms in molecule of IBr can be described as ##V(r)=V_0[(\frac{r}{a})^{-8}-10(\frac{r}{a})^{-4}]##, where ##a=1nm## and ##V_0=0.1eV##. Calculate the first three vibration states if the potential close to minimum is harmonic. ##M(I)=127g/mol## and...

Problem: Show that the combined spring energy and gravitational energy for a mass m hanging from a light spring of force constant k can be expressed as 1/2 ky2, where y is the distance above or below the equilibrium position. Figure shows a block connected to spring, where equilibrium is...

Can you guys give me example for conduction, convection, radiation energies ?

The bond enthalpies for these bonds are: C-C 347 kJ/mol C-N 276 kJ/mol C-O 351 kJ/mol Why is carbon-nitrogen bond enthalpy lower? What factor makes that? And also the halogens bond enthalpies: F-F 157 kJ/mol Cl-Cl 243 kJ/mol Br-Br 193 kJ/mol I-I 151 kJ/mol Why has fluorine lower enthalpy? I...

Homework Statement A beam of 13.0 eV electrons is used to bombard gaseous hydrogen in ground state. What photon energies will be emitted?Homework Equations ΔE = -13.6 (\frac{1}{n^{2}_{f}} - \frac{1}{n^{2}_{i}}) However hydrogen is in the ground state therefore n_i= 1: ΔE = -13.6...

I don't really understand the explanation given in Binney's text about: Hamiltonian is given by: H = \frac{\hbar^2}{2} \left( \frac{J_x^2}{I_x} + \frac{J_y^2}{I_y} + \frac{J_z^2}{I_z} \right) Orient axes such that ##I_x = I_y = I##. H = \frac{\hbar^2}{2} \left( \frac{J^2}{I} +...

Hello, This latest homework I have been doing has been very confusing to me and I have spent hours trying to complete it. Here is a problem that I really don't know where to start. If anyone could just point me in the right direction, or let me know if my ideas are correct or not, it would...

I was reading my quantum mechanics text and I have a doubt. I have the energy levels well defined for the finite square well and the author suddenly compares (I believe) those levels with the levels of the nucleon with the following phrase: "is the spacing between levels on the order of MeV for...

http://i.imgur.com/QFRCRZr.jpg (the black numbers are just so i can make references throuhout this thread, they're not part of my notes) (z is the partition function for Boltzmann statistics) so the first four lines is just expanding an expression for the average internal energy of a system...

Homework Statement A particle is confined to a two-dimensional box defined by the following boundary conditions: U(x, y) = 0 for \frac{-L}{2} ≤ x ≤ \frac{L}{2} and \frac{-3L}{2} ≤ y ≤ \frac{3L}{2}, and U(x, y) = ∞ outside these ranges. Determine the energies of the three lowest energy states...

In which situation is Work done (F.d) equal to Kinetic energy, Potential energy and both kinetic & potential energy at the same time?

Hello, I don't understand something in this exercice and i have another question:Homework Statement Use separation of variables in Cartesian coordinates to solve the infinite cubical well (or "particle in a box"): V (x, y, z) = { O,if x, y, z are all between 0 and a...

Homework Statement An unstable particle of mass M = m1 + m2 decays into two particles of masses m1 and m2, releasing an amount of energy Q. Determine the kinetic energies of the two particles in the CM frame. Given that m1/m2 = 4, Q = 1 MeV, and that the unstable particle is moving in...

This question came up in a textbook and not everyone agrees on the solution. The question is: "A 63 kg diver is standing on a diving board waiting to commence her dive. The diving board has compressed 8.0 cm. Determine the elastic potential energy of the diver." The solution given by the...

Homework Statement The energy of particles in a flame at a temperature T might be described by a Boltzmann distribution. Temperature can be converted to energy (and thereby velocity) using the gas constant R = 8.3145 J mol-1 K-1. Let us approximate thermal energy in the flame by RT (squiggly...

Homework Statement In class, we discussed metal quantum dots, and we argued that they’re not so useful for device applications since the separation between energy levels for energies near the Fermi energy is much less than a typical optical photon energy of 2 eV. Let’s consider that...

Is there a way to know qualitative information about energy spacing of bound state energy? Infinite square well. V=0 -a/2<x<a/2 V=∞ otherwise Bound state energy E\propto n^2 space beteween succesive energies increases at higher energy (n+1)^2-n^2=2n+1 Harmonic Oscillator V\proptox^2 E\propto...

Homework Statement Blue light corresponds to free space wavelengths of approximately 450 to 495 nm. If we want to use a semiconductor to make a blue LED, what range of energies must the semiconductor's bandgap fall within? Express your answer in units of electron volts(eV). What is an...

Photons need specific energy levels, equal to the difference between two energy levels to excite an electron in an atom. Is this the same case with electrons that collide with atoms?

Homework Statement Calculate the energy for 1S->2P transition in lithium and carbon. We had to calculate the energy and eigenvalue equations (though I verified these are correct) Homework Equations E = mc^2/sqrt(1+(Za/lambda)^2) lambda = n + 1/2 + sqrt((l+1/2)^2- (Za)^2) The...

I'm trying to understand an RF induced chemical vapor deposition process. Without getting into anything complicated I get of got hung up on how to equate energies. So I'm imagining a parallel plate capacitor that has charged particles oscillating between the two plates (or thinking of a...

Hello, I'm trying to solve for the allowed energies with the WKB approximation of the Schrodinger equation, using the Morse potential. So I have (as per equation 35 at http://hitoshi.berkeley.edu/221a/WKB.pdf), \int_a^b \sqrt{2m(E-V(x))}dx=\left(n+\frac{1}{2}\right)\pi\hbar However, how do I...

Hi! In my lab class, we are using a photomultiplier to examine gamma ray emission lines and determine absorption coefficients of different radioactive materials. Homework Statement As we test for absorption (by layering on metals, incrementally increasing the thickness), we consider spectral...

Ordinary photovoltaics work by depleting phosphorus un boron doped silicon in eatch other and creating a permenant electric field, which then separates any pair of hole and electron induced to the conducting band by a incoming photon, creating an aditional elekctric potential difference, which...

Hello I understand how to approach finite potential well. However i am disturbed by equation which describes number of states ##N## for a finite potential well (##d## is a width of a well and ##W_p## is potential): $$ N \approx \dfrac{\sqrt{2m W_p}d}{\hbar \pi} $$ I am sure it has something to...

Question: The top of a chute whose length is 12 meters is 3 meters vertically above its lowest point. A parcel of mass 1.6 Kilogram slides from rest from the top of the chute and reaches the lowest point with a speed of 5 meters per second. Calculate, for the the parcel: (A) The gain in Kinetic...

Problem: In a harmonic oscillator \left\langle V \right\rangle=\left\langle K \right\rangle=\frac{E_{0}}{2} How does this result compare with the classical values of K and V? Solution: For a classical harmonic oscillator V=1/2kx^2 K=1/2mv^2 I don't really know where to begin. Is it safe...

What is the meaning of "orbital energies"? Could someone please explain, because I am confused: or is it the same as energy level of an electron, I mean the energy that one electron contains in a certain shell? Thanks for the help!

1. The ionization energies of Rb and Ag are 4.28 eV and 7.57 eV, respectively. Calculate the ionization energies of an H atom with its electron in the same orbitals as the highest energy electrons in these two atoms. Another way of thinking of this is: what would the ionization energies of RB...

Hey, I am working on a project where I have to come up with a way to recover energy from heat of a fire. we were thinking several options such as: - Thermoelectric materials and steam turbines which would convert heat to energy - Stirling engine to convert heat to mechanical energy...

X-ray question -- frequencies and energies Homework Statement 1. Why does x-ray with higher frequency possesses higher ionizing power and penetrating power ? 2. Will gamma ray with higher frequency possesses higher ionizing power and penetrating power ? And is "gamma ray has no mass" a reason...

Hi, I am reading in some books that after the \beta-decay of neutrons, the maximum energy of the resulting electron is a bit less than 800 keV. In some cases, however, I see that in e.g. some studies that try to extract the electron energy from \beta-decay of neutrons with some Monte Carlo...

Hey, This question is on determining the energies of a two particle system given the Hamiltonian, I believe it to be simple enough but would like you guys to check it and fill in any gaps in my reasoning So I believe the eigenvalues of J^2 and J^2(z) are given by: \hat{J}^{2}:j(j+1)\: ,\...

When a system of particles condensates, are energy released or aborted? Is energy required to condensate a bunch of particles? In one example, if you were to shrink the volume these particles should occupy by exerting pressure to the container, energy is required. Where do these energies go...

Hello. I have a tiny question that has confused me. Currently I'm reading about potential wells, harmonic oscillators, the free particle in quantum physics. If I just take the particle in a box as an example you have a region where the potential is zero, and you have some walls/boundaries...

Homework Statement During a discussion, we tried to figure out, according to the Bohr model of the atom, what happens when radiation with a higher energy level than that which can ionize hydrogen. Homework Equations Absorption spectrum of hydrogen. Ionization energy of hydrogen - 13.6...

Homework Statement A 5.00-kg block is set into motion up an inclined plane with an initial speed of 8.00 m/s. The block comes to rest after traveling 3.00m along the plane, which is inclined at an angle of 30° to the horizontal. For this motion, find the change in the block's kinetic energy...

Hey guys, I am having trouble understanding/explaining some of the trends in ionization energy with calculated Zeff by slaters rules. For example I was asked why is the 3rd ionization energy for Be greater then the 3rd ionization energy for O My train of thought was to say its pulling an...

I have a quantum problem that I can't seem to figure out: There's an electron in a 1-D rigid box of length 2A but it is known to reside in a central segment of 1A with uniform probability of residing within this segment. There are two possible wavefunctions: one with constant phase...

hello! I come across various "energies", like free Gibbs energy, enthalpy, entropy, etc (okay, to be precise, entropic energy, enthalpic energy, internal enegry, etc) I wonder, why all these energies? the energy of a system stems from the movements of its components and the potential...

I really need help with conceptual understanding of this topic. Heres the question: What happens to Energy of source, delta KE, delta Potential, delta Energy Dissipated, and Work of the systems in the question? Basically it's asking the initial and final of these. The problem is: a car pulls a...

Lets say I have a system ψ with a Hamiltonian matrix H and energy eigenvalues E. Just a general system, with no particular basis given. When I solve the eigenvalue equation for H, and get zero or negative numbers or zero for E, is that physical? If it is not physical, do the negative numbers or...

I need an explantion of the following description of plasmon, "Plasmon energies in the range of 5-30eV for electron systems of metallic densities,consequently they play no role in determining the thermodynamic properties of the electron system." What kind of thermodynamic properties are...

In band theory of solids, when an electron's wave vector lies at the first brillouin zone border, it satisfies the bragg condition and there is some forbidden region for that wave vector. I like to know what happens for such these electrons that they can not have some energies in the forbidden...

Ok, first time posting...hopefully I do this correctly, as I have found myself in a bind on this one. It is a question comparing the mechanical energy of two masses falling in different ways in which you are given the option of greater than, less than, or equal to. Homework Statement The...

The general question that I am interested in, is to obtain the number of bits of information one can infer about the horizon by placing measuing apparatus only in a Region of size D. I Imagine a telescore of diameter D that(or devices of that general nature) The standard Theory says that*...

Quantum field theory predicts a value for the cosmological constant that is 123 orders of magnitude larger than the observed value (if one assumes the Standard Model to be correct up to the Planck scale of 10^19 GeV)! To theoretically predict the value of the cosmological constant, one must, I...