What is Energy change: Definition and 91 Discussions

The Department of Energy and Climate Change (DECC) was a British government department created on 3 October 2008, by then Prime Minister Gordon Brown to take over some of the functions related to energy of the Department for Business, Enterprise and Regulatory Reform, and those relating to climate change of the Department for Environment, Food and Rural Affairs.
It was led at time of closure by the Secretary of State for Energy and Climate Change, Amber Rudd MP. Following Theresa May's appointment as Prime Minister in July 2016, the department was disbanded and merged with the Department for Business, Innovation and Skills, to form the Department for Business, Energy and Industrial Strategy under Greg Clark MP.
The Department released a major White Paper in July 2009, setting out its purpose and plans. The majority of DECC's budget was spent on managing the historic nuclear sites in the United Kingdom, in 2012/13 this being 69% of its budget spent through the Nuclear Decommissioning Authority. The costs to the government of nuclear decommissioning are expected to increase when the last of the United Kingdom's Magnox reactors are shut down and no longer produce an income.

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  1. D

    Energy of a water tank with compressed air

    At sealevel, the water in the tank is just mgh so 1000 kg * g * 1m so about 10 kjoules. Now if we pump air until it is 2 atm. The potential energy of a compressed gas is given by the formula: U = -nRTln(V2/V1) But in this case it is not the gas that we care about but the water. I can...
  2. LCSphysicist

    Energy change under point transformation

    How do the energy and generalized momenta change under the following coordinate transformation $$q= f(Q,t)$$The generalized momenta: $$P = \partial L / \partial \dot Q = \partial L / \partial \dot q\times \partial \dot q / \partial \dot Q = p \partial \dot q / \partial \dot Q = p \partial q /...
  3. G

    Change in Internal Energy in Accelerated Gas Chambers

    Summary:: How internal energy changes in a acclerated cabin. There are two tourus shaped insulated closed pipes containing equal amounts of ideal gas under same conditions. B has a adiabatic partion wall. If both are to change angular velocity by w radians per second. How internal energies...
  4. S

    Energy change in a nuclear reaction

    I got 6.5 MeV but I don't understand how to determine whether the energy is released or absorbed. My guess: the energy is absorbed because mass defect of neon is bigger? Thanks
  5. B

    Solve for the total Kinetic Energy change with unknowns

    Firstly I tried defining into an equation to make the whole thing more 'tangible'. ##m_1= Paula's~Weight⋅2 = m_p⋅2## ##m_2= \frac {Dave's~weight}{2} = \frac {m_d}{2}## Before impact ##E_k1= \frac 1 2 (m_p⋅2)(0^2)## ##E_k1= \frac 1 2 (2m_p)## ##E_k1= m_p ## After Impact ##E_k2= \frac 1 2...
  6. S

    Algebraic Improvement needed in Comparing enthelpy and internal energy change

    MODERATOR'S NOTE: I have been having difficulty explaining to this member the error in his algebraic development, in particular being cavalier in his attentiveness to proper algebraic manipulation of signs. I explained his error in post #7 (and the problems that could arise if he continues to...
  7. cooldudeachyut

    Enthelpy & Internal Energy Change relation with Cp & Cv

    Homework Statement Match the following Given : Processes do not include chemical reactions. Assume CP,m and CV,m are independent of temperature for given substance and consider only pressure-volume work in given all processes. Homework Equations ΔU = Q - W ΔH = ΔU +...
  8. G

    Calculating Potential Energy Change for a Mountain Climber

    Homework Statement A 95-kg mountain climber hikes up a mountain to an elevation of 5000 m. What is the change in the climber's potential energy? Homework Equations I might be missing something but here's everything that might be relevant: w=fx p=w/t p=f*v KE=1/2mv^2 PEg=mgh PEe=1/2kx^2 Wnet=E...
  9. S

    B Can energy change physical laws?

    Could huge amounts of energy change the universe's nature (fundamental physical constants, laws, dimension)? Could it change it so much that it would enable our universe to be a multiverse of level 1, 2, 3 or 4? https://en.wikipedia.org/wiki/Multiverse
  10. V

    Energy change for a charged particle

    Homework Statement Without introducing any coordinates or basis vectors, show that, when a charged particle interacts with electric and magnetic fields, its energy changes at a rate $$\frac{dE}{dt}=\vec{v}\cdot \vec{E} $$ Homework Equations ##E_{kin} + E_{pot}= En =## const (1)...
  11. hebejere

    Neutron velocity, energy change time/distance

    this is really basic I know but i would like to know if a neutron ,positron or alpha particle of a given energy will lose energy and velocity as it travels through space would atmospheric molecules have a significant effect as well on velocity/energy level. and if they do lose energy what form...
  12. Arman777

    I Emitting Photon and Energy Change

    I know that my title is not very suitable for this question, but I couldn't find right words to describe the situation.I read a book called '101 Quantum Questions ' and there writer states that when electron absorbs energy and goes higher energy level, we don't know when and where it will come...
  13. C

    I How can an atom change from ground to excited state?

    I am currently studying a Foundation Program, which includes chemistry. -I can easily understand the distinguishable characteristics between ground and excited state via writing the electron configuration. -But how can an tom changes from ground to excited state ? And can an atom changes from...
  14. Andy_K

    I Is Time Merely the Progression of Energy Toward Equilibrium?

    Can we say that TIME is essentially the progression of energy from one state to another, in its long cosmic quest to achieve equilibrium? Without the movement of electromagnetic waves and transfer of energy, the entire universe would come to a standstill — an inanimate, “frozen” world. Time...
  15. H

    Kinetic energy change with initial velocity

    It is my understanding that to calculate the change of kinetic energy of an object that speeds up from vi to vf you use this formula: Change of kinetic energy = 1/2 * m * (vf2 - vi2) When the initial velocity is 0 m/s I have no problems, but let's say an object that weighs 2 kg speeds up from...
  16. N

    Energy Change Nuclear Chemistry

    Homework Statement Determine the energy change, delta E, in J when 500 g of 229/90 Th undergoes the following nuclear reaction: 229/90 Th --> 225/88 Ra + 4/2 He The nuclear masses in amu or g/mol are: Th-229: 229.03175; Ra-225: 225.02360; He-4: 4.00260 Homework Equations delta E = deltam(c)^2...
  17. Lil Uzi Vert

    How to Calculate Energy Change for Lifting an Object on Earth and the Moon?

    Homework Statement A person performs 6.1 J of work to lift an object without acceleration to a particular height on Earth. Write an equation describing that energy change and analyze it to determine how different the energy would be required to lift the same object to the same height on the...
  18. A

    When does potential energy change?

    Why doesn't the potential energy of a substance change when the pressure changes? Or in what case will the potential energy of a substance change?
  19. M

    Derivation of rate of energy change from Lorentz force

    I am trying to derive from the Lorentz force equation the time derivative of the total energy. This involves using the equation for the jth electron in an electron beam traveling through an undulator. I have done it in such a way using the work done relation however I have been told that it is...
  20. S

    Energy change of reservoir in reversible weight process

    In what follows I refer to the ideas of "Thermodynamic: Foundations and Applications" by Gyftoploulos and Beretta. The abbreviated form of my question is: In a reversible weight process, Ω1R-Ω2R = E1 - E2 (see eqn. 6.18, p. 99) is transferred out of the composite of a system A and a reservoir R...
  21. D

    Final Frequency and Kinetic energy change?

    Homework Statement Hi I know my picture has 2 problems, but let's just focus on the first problem parts a and b. So for part a it ask for the final frequency after the ant landed, and part b is the kinetic energy difference. Basically the ant=.01kg, diameter of cylinder is .115m, the weight of...
  22. normal_force

    KE1 vs KE2, mechanical energy change

    Homework Statement If two objects of unequal mass and unequal Kinetic energy hit each other, they lose some energy to other forms but keep enough to do Work on each other. A good example is a car and wind, a man and ball could also apply, a ball with KE could stop a running man if KE does work...
  23. R

    Understanding Deceleration: Investigating the Force and Energy Changes on a Ship

    Homework Statement 1.If the ship has a mass of 2.5 x 10^7 kg calculate the magnitude of the force acting on the ship during the deceleration. I was trying to work that out using f=ma but that would Make the force negative , is that possible 2. What is the nature of the force acting on the...
  24. Ariel Jo

    Calc ∆Ho & ∆Eo for CH3OH Reaction @ 298K

    Homework Statement For the reaction CH3OH(l) → CH4 (g)+ 1/2 O2 (g)[/B] (a) Calculate ∆Ho298 (b) Calculate ∆Eo298 (c) Write an equation that would allow you to determine ∆H at 500°C and 1atm Homework Equations ∆H=∆E+∆(PV) ∆H=Σ∆Hproducts-Σ∆Hreactants The Attempt at a Solution a)...
  25. A

    Ideal gas process internal energy change

    Homework Statement A sample of an ideal gas goes through the process shown in Figure P20.32. From A to B, the process is adiabatic; from B to C, it is isobaric with 100 kJ of energy entering the system by heat. From C to D, the process is isothermal; from D to A, it is isobaric with 150 kJ of...
  26. S

    Why is the internal energy change of free expansion 0?

    ΔU=q-w and in a free expansion w=0 and Free expansion is an irreversible process in which a gas expands into an insulated evacuated chamber. Does this mean that free expansion is an isolated system? Meaning the walls of the container are adiabatic in which no heat can enter the system and so q=0...
  27. Teemo

    Internal Energy Change: Homework Solutions

    Homework Statement Internal Energy Change Homework Equations N/A The Attempt at a Solution If internal energy change equals enthalpy change, then I am looking for the reaction which has the enthalpy change closest to zero. I know it cannot be A, as the formation of water is highly exothermic...
  28. C

    Thermal Physics: Energy change due to compression

    This is not a homework problem but rather a passage from my textbook that I don't understand. I don't think I quite understand the concept of reversible processes. Here is the passage from my book: "Consider a system in the quantum state s of energy Es. We assume Es to be a function of the...
  29. T

    How does kinetic energy change in circular motion?

    Could someone explain to me how the kinetic energy of a body moving in a circle is like? I got tempted it stays constant as the speed is constant but that turned out to be false. I am interested in places where the body is at top, side and bottom and so on. So I'd like to also know what the KE...
  30. J

    Relationship between Free energy change and Equilibrium constant (K)

    1. I have a question regarding the equation ΔG° = -RT lnK. When solving for the equilibrium constant K, what is the relationship between the vapor pressure of each molecular compound in a reaction? ΔG° = Free energy change R = Universal gas constant T = Temperature K = equilibrium...
  31. T

    Internal Energy Change: Confusion Cleared Up

    Hi Guys! I have a confusion which I hope you can help clear up. The mathematical expression of the first law of thermodynamics can be stated as δu=Q+W where u is the internal energy of the system, Q is the heat added(or taken from) to the system and W is the work done by or on the system. If I...
  32. W

    Calculating energy change (rydberg?)

    Ok, so here's the question: An electron in an atom is excited by heat. In the process electromagnetic radiation of wavelength 1x10^-7 is produced. Calculate the energy change. Do not get this at all in any way. I have to take an atomic physics module but I really really can't do any of it...
  33. N

    Thermodynamics: Enthelpy and energy change of a column of air

    Homework Statement A column of dry air, of cross-sectional area 1m2, has a surface pressure of 1atm. Over the course of several hours during the day it gains 2MJ of energy from radiation and surface heating. There are no horizontal exchanges of energy of mass, and it remains in hydrostatic...
  34. T

    Change in Energy Stored in a Capacitor Due to Removal of Dielectric

    Homework Statement (a) The separation between the plates of a parallel plate capacitor is 2 mm and the potential diff erence between them is 45 V. Find the electric field between the plates. If the permittivity of the dielectric medium between the plates is 20 \epsilon0, fi nd the charge...
  35. gfd43tg

    Standard Gibbs energy change definition

    Hello I am working on deriving the expression relating the equilibrium constant K to the change in Gibbs energy. This part seems to be followed okay, but here I am not following why the change in Gibbs energy of reaction is defined this way. I can see why K is defined in a way because...
  36. B

    Can Charge and EM Energy Change Metal Structure

    Hello Everyone, This is my first post. Background: I am an audio guy and seek to understand how cables contribute to the sound of my stereo. Issue: Do audio cables such as power cords, interconnects, and speaker cables "break in" as they are used? Typically, with high-end cables, users...
  37. M

    Exploring Free Energy Change: ΔG, ΔH, and ΔS

    If ##ΔG_{sys} = ΔH_{sys} - TΔS_{sys}; ΔS_{sys} = \frac {-ΔH_{surr}}{T} ## Then, doesn't this expression just simplify to: ##ΔG_{sys} = ΔH_{sys} + ΔH_{surr}## and isn't ##ΔH_{sys} = -ΔH_{surr}##? So then ##ΔG = 0##...this does not seem correct...could anyone please clarify my mistake and...
  38. pratikaman

    Does Potential Energy Always Decrease with Conservative Force?

    is it true that potential energy of a particle always decreases in the direction of conservative force acting on it.
  39. A

    Why can't energy change abruptly?

    Hi, I want to ask your help about energy. Why can't energy change abruptly? If energy E changes abruptly then power P = dE/dt = ∞. I would like to know why this is impossible? I know that energy has to be conserved and they can only change from one form to the other. But why this process...
  40. S

    What is the significance of Gibbs Free energy change in chemical reactions?

    In reaction there is a Gibbs Free energy change. I'm still not sure what this means as in my secondary school years we just learned of one component of it which is the enthalpy change. That was simple as it just showed how much heat was released or absorbed. But with Gibbs Free energy, i don't...
  41. A

    Does Work Equal Total Work + Internal Energy Change?

    Ok, if it says that change of internal energy is part(for example 1/3) of TOTAL work executed over system(body). Does it mean that is TOTAL work indeed sums of every single work(mechanical work+internal energy change+...) ?
  42. B

    Heat energy change when gas compressed

    Homework Statement One mole of an ideal gas is in a container with a moveable piston. A 100 N force moves the piston down 1 m; the compression is isothermal. Does 100 J of energy leave the gas or enter the gas? Homework Equations W=Fd U=Q-W=Q-P(Vf-Vi) The Attempt at a Solution...
  43. D

    Free energy change during adsorption

    Hi, Suppose I have a dissociative adsorption reaction and want to find the free energy change ΔF, this can be written at constant temperature: \Delta F = \Delta E -T\Delta S Now given the adsorption energy \Delta E_{ads} I would like to extrapolate the Free energy assuming that the adsorbate...
  44. N

    Gibbs Energy Change and Maximum Work

    Homework Statement I am trying to understand the implications of the principle that the maximum non-expansion work, dwadd is equal to the Gibbs energy change for a reversible process. Homework Equations For a reversible process, dwadd = dG. This is provided that the process takes...
  45. R

    Kinetic energy change during phase change

    hi all, its been hours that i could not find a decent answer for a 'simple' Q: during a phase change (say, boiling) the temp' doesn't change, as we all know. we also know that the temp' is a measure of the system kinetic energy (KE). im interested to know how the average KE AND its...
  46. B

    Standard Gibbs' energy change

    My thermodynamics textbook says that chemical potential can take any of the following symbols: μ (condition-dependent), μ∇ (standard), μΘ (standard) (superscript plimsoll line) and μO (standard), with which one of the latter 3 being used depending on the temperature chosen to define standard...
  47. J

    Energy change of apparatus when gaws suddenly expands

    Energy change of apparatus when gas suddenly expands Homework Statement A gas is confined in a cylinder by a piston. The initial pressure of the gas is 7 bar(700kPa), and the volume is 0.10m^3. The piston is held in place by latches in the cylinder wall.The whole apparatus is placed in a...
  48. S

    Potetial energy change during heating

    Homework Statement when heating i learned that only the kinetic energy component of internal energy increases. However, I also learned that potential energy is related to distance between the particles. So when i heat some solid and it expands does it mean the potential energy has changed as...
  49. R

    Does potential energy change mass

    Hello everybody. Imagine a box in which two spheres are separated by some distance. nothing is moving inside. Einsteins E=m*c^2 must be always valid. Since nothing moves the energy of box is E=m°*c^2 where m° is rest mass. Since the spheres exert gravitational force on each other they will be...
  50. C

    Internal energy change in isobaric system

    hi all, i have a confusion about the internal energy change and work done in a isobaric system... suppose i want to find the delQ in isobaric system in terms of P & V...now i may assume the delW part would be pdv=p(V2-V1)...as i m compressing the gas... but what happens to the du? and is the...