Energy conservation Definition and 434 Threads

Energy conservation is the furniture made to reduce the consumption of energy by using less of an energy service. This can be achieved either by using energy more efficiently (using less energy for a constant service) or by reducing the amount of service used (for example, by driving less). Energy conservation is a part of the concept of Eco-sufficiency. Energy conservation measures (ECMs) in buildings reduce the need for energy services and can result in increased environmental quality, national security, personal financial security and higher savings.
It is at the top of the sustainable energy hierarchy.
It also lowers energy costs by preventing future resource depletion.Energy can be conserved by reducing wastage and losses, improving efficiency through technological upgrades and improved operation and maintenance. On a global level energy use can also be reduced by the stabilization of population growth.
Energy can only be transformed from one form to other, such as heat energy to motive power in cars, or kinetic energy of water flow to electricity in hydroelectric power plants. However machines are required to transform energy from one form to other. The wear and friction of the components of these machine while running cause losses of very high amounts of energy and very high related costs. It is possible to minimize these losses by adopting green engineering practices to improve life cycle of the components.Energy conservation day is celebrated on December 14 every year since 1991.

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  1. Y

    Understanding energy conservation in a solenoid

    So let's assume ideal wire, resistance = 0 Ohms. Also assume there is a magnetic ball 1 meter away and is attracted to the solenoid. If you have a loop of wire and run a small current through it, you get a magnetic field. This field attracts the magnetic ball, over a distance of 1 meter. If...
  2. kuruman

    Can We Do Better Than Mechanical Energy Conservation?

    Continue reading...
  3. r12214001

    Using Energy Conservation to solve this problem: Jumping on a spring scale

    I suppose spring compression to be X when jumpping from 1m. Therefore gravational potential mgh=760(1+X) and my cal:760(1+X)=0.5kX² why the solution manual state that 760=0.5kX²+760X
  4. kuruman

    Is Mechanical Energy Conservation Free of Ambiguity?

    [url="https://www.physicsforums.com/insights/is-mechanical-energy-conservation-free-of-ambiguity/"]Continue reading...
  5. mgkii

    EM Wave - basic question on energy conservation in a wave

    I've searched threads and can't find easy explanation - sorry if I'm missing something basic / have a basic understanding error! In the classic picture of an EM wave with the Electric and Magnetic components oscillating at 90 degrees to each other, both components cross the middle axis at the...
  6. A

    Energy conservation for objects hanging from a pulley

    I have some conceptual questions about this task. In order to get the correct result (I checked the textbook answer) in part (a) I had to assume that the speed for each block is the same at all instants. And that if one block moves down x meters, the other one will move up that same amount of...
  7. Physicsboi123

    Energy Conservation of a Vertical Spring

    Using conservation of energy, 0.5kx^2=mgh=mgx 0.5kx=mg 0.5kx=mg, x=0.15, m=9, g= 9.8 So isn't it k= 1176N/m? For this problem, I understand that you can't use conservation of energy, but why? There is gravitational potential energy at the top and spring elastic energy at the bottom, and no...
  8. CaglarKorkmazgoz

    Why Can't Forces Replace Energy Conservation for Spring Stretch?

    Hello, I am new on this forum, so if I make any mistakes please inform me. Thank you. I wonder why I cannot use forces instead of energy conservation in this question. The question is: "How far (x = L) does the spring stretch before the masses stop moving? Express your answer in terms of m, k...
  9. U

    Energy Conservation as an explanation for v=0 for spring mass system

    My Solution: For the displacement graph, the gradient is crucial to predict the behaviour of the displacement of the block through time. At 1: System is released - velocity is zero, considering forces acting on block, kx < mg, as block is observed to move downwards, and object is...
  10. K

    Closest approach from initial velocity and impact parameter

    Here were my assumptions: Energy and angular momentum are both conserved because the only force acting here is a central force. The initial angular momentum of this particle is ##L = mv_0b## and we can treat E as a constant in the homework equation given above. I solved for the KE (1/2 mv^2) in...
  11. H

    Does action at distance in electromagnetism violate energyconservation

    Consider two charges A and B separated at distance D. charge B is attached on spring and can move towards and away from charge A. Now charge A is brought closer to charge B and then it is taken back to its original position. Work done in this process is zero because of conservative forces. If...
  12. Van Ladmon

    I Conflict of domain and endpoints in Noether's theorem

    In the derivation of energy conservation, there is the transformation ##q(t)\rightarrow q'(t)=q(t+\epsilon)##, whose end points are kind of fuzzy. The original path ##q(t)## is only defined from ##t_1## to ##t_2##. If this transformation rule is imposed, ##q'(t_2-\epsilon)=q(t_2)## to...
  13. D

    Bicycles: Question about Energy Conservation

    I just have a basic physics question about bicycles that has been confusing me. Consider three situations. In the first situation a person, of mass m, is running down a street at constant velocity v1. In this case the person is converting energy stored in their body into translational kinetic...
  14. H

    If a magnet does not feel the Lenz force, will there be a violation of energy?

    Consider the following, a magnet and a charge is attached to a platform, which is constrained to move only up and down direction. Now, if magnet is moved towards charge, due to changing magnetic field, an electric field will be created. This electric field will impart force on charge. since the...
  15. EEristavi

    Energy Conservation in Angular motion / Moment of Inertia

    I write Conservation of Energy: Potential Energy loss(change): U = m g ##\Delta##h = m g (R+r) (1-cos##\alpha##) kinetic Energy gain(change): K = (##\frac {m v^2} 2## + ##\frac {I \omega^2} 2##) + (##\frac {M v_2^2} 2## + ##\frac {I_2 \omega_2^2} 2##) U = K m g (R+r) (1-cos##\alpha##) =...
  16. C

    B Energy conservation in nuclear fission

    Hi all, I struggle to understand how energy is conserved I fission. If the binding energy per nucleon increases, surely the mass defect simply accounts for that difference to conserve energy before and after. How does the mass defect account for the kinetic energy of the fission fragments as well?
  17. Harperchisari

    The energy conservation issue with parallel charged plates with a hole.

    A while back I thought of an issue with parallel charged plates. Imagine this: a set of opposite charged resistive plates with holes in the center. In theory, there is a finite amount of energy required to push a positive charged particle through the hole in the positive plate (in theory it...
  18. navneet9431

    Is it possible to apply energy conservation here?

    Homework Statement Homework Equations Kinetic Energy =1/2*m*v^2 Spring Potential Energy = 1/2*k*x^2 Gravitational Potential Energy = m*g*h The Attempt at a Solution I am thinking to solve this problem using energy conservation but I feel that it is not possible to apply energy conservation...
  19. Cc518

    Object A is stationary while objects B and C are in motion.

    Homework Statement Object A is stationary while objects B and C are in motion. Forces from object A do 10 J of work on object B and –5 J of work on object C. Forces from the environment do 4 J of work on object B and 8 J of work on object C. Objects B and C do not interact. What are ΔKtot and...
  20. O

    Energy conservation and friction

    Hi, I just started learning physics at university and so I'm looking for help on a simple energy conservation problem. On the bottom right-hand of the image I attached below, you should see that it asks whether the initial speed would increase or decrease if the object was of a greater mass...
  21. Euthan

    I Energy stored in space-time or space?

    I was talking to a graduate physics student about the issue of energy conservation in an expanding universe. I paraphrased the argument against energy conservation as follows - Suppose we have a photon in outer space that is very far from earth. The universe is expanding (by this I meant that in...
  22. Krushnaraj Pandya

    Energy conservation in an alpha-scattering experiment

    Homework Statement In scattering experiment, find distance of closest approach if a 6 MeV alpha particle is used 2. The attempt at a solution initially KE of alpha particle is 6 x 10^6 x e joules and 0 PE, finally its PE is kq1q2/d, k=9 x 10^9, q1=4e, q2=Ze=79e (assuming gold), d is distance...
  23. YoungPhysicist

    Do magnets lose strength by pulling them apart?

    When two magnets already sticked to each other being pulled apart, energy is applied, so I assume that the energy is stored like some sort of potential energy which will be turned back into kinetic energy when they accelerate towards each other to stick back together. So the magnet itself...
  24. M

    Understanding an electron's emission of electromagnetic waves

    Hi to everybody ! I was thinking about something which confuses me about wave emission. The question is simply the following: Does an electron emit light when it accelerate? or just during its deceleration? or maybe when acceleration and deceleration alternates in some order? I'm not really...
  25. Almighty BOB

    A Energy conservation on Cosmological scales

    I'm curious to know whether anyone with good maths has anything to say about Dr Philip Gibbs' covariant formula for conserved currents of energy, momentum and angular- momentum derived from a general form of Noether’s theorem? I'm not a pro mathematician, but it looks relatively robust to me...
  26. Turukano26

    Calculating the frequency of a free electron

    I feel like I must be missing something obvious, but I can't figure it out. I have the speed of an electron, and to calculate its frequency i used p = h/λ, then subbed in p =mv and λ= v/f. Giving me the equation f = mv2/h. However, I also could use E = 1/2 mv2 and E = hf to give me the equation...
  27. binbagsss

    GR- Energy conservation, effective potential graph sketch

    Homework Statement I would like to ask about parts c) and d) , the graph sketching bits. 2. Homework Equations ##V(r) = ( \frac{J^2}{r^2}+\epsilon)(r-\frac{1}{r}) ## where the value of ## \epsilon ## is set according to whether time-like or null etc. The Attempt at a Solution Q1)for...
  28. Ironman1998

    Can energy conservation be violated?

    I think energy can be created...i agree that energy is not conserved between different reference frames..but i can show you that energy measured in a single frame may wary... Does photon's energy increase when i emit it from a train which is moving at comparable speed and get it reflected back...
  29. Z

    Derivation of the energy principle from Gregory Classical Mechanics textbook

    I'm working through Gregory's Classical Mechanics and came across his derivation of energy conservation for a system of N particles that is unconstrained. We get to assume all the external forces are conservative, so we can write them as the gradient of a potential energy. There's a step he...
  30. C

    Finding angular velocity using conservation of energy

    Homework Statement In the document below I need to try and find the angular velocity I need help on part b Homework Equations F=ma KE_Translational= 0.5mv^2 KE-Rotational= 0.5Iw^2 Assuming g=10m/s^2 The Attempt at a Solution I have the answer key attached with the question but I am not sure...
  31. M

    What is the solution to question 2 on energy conservation problems homework?

    Homework Statement https://www.img.in.th/image/VNYMHY https://www.img.in.th/image/VNYKDv This is my homework,but I have a problems with question no.2 Homework EquationsThe Attempt at a Solution I tried to used energy conservation rule to get that the speed is √2gh ,but I don't know how to know...
  32. M

    Conservation of momentum - with understanding

    I just want to state that i DID solve the problem. I just seek understanding of it. I'd be really grateful if someone could answer two of my questions at the end of this post. The problem I've solved here is just to show what I'm dealing with. 1. Homework Statement Object 1 is moving towards...
  33. Jezza

    I Quark mixing and energy conservation

    We've recently been looking at the hadronic decays of the W boson. In this one example, we looked at possible decays for the W boson being produced near its resonance peak, meaning the centre of mass energy is sufficient to produce u,d,c,s & b quarks. However, because we're below the mass of...
  34. E

    Momentum and energy conservation in a vertical loop

    Homework Statement Two beads with masses of M and m are threaded on a vertical loop with radius of R. M is released without velocity from a height of 1.5R from the bottom of the loop. The collision between the beads is completely elastic. What is the smallest mass M that will make the second...
  35. F

    Energy conservation in circular motion

    Homework Statement An object of mass m = 1 kg moves along a circular frictionless path of radius R = 0.5 m from point A to point B at which it makes an angle θ with the vertical direction as shown in the figure. If the object is release from rest (VA = 0) and θ = 30° , what is the normal force...
  36. H

    Mechanics - Hooke's law and energy conservation

    Homework Statement One end of a light elastic string of stiffness mg/l and natural length l is attached to a point O. A small bead of mass m is fixed to the free end of the string. The bead is held at O and then released so that it will fall vertically. In terms of find the greatest depth to...
  37. S

    I Velocity addition and conservation of the energy

    Hello everyone, For some time I'm a little bit confused about (at the first view) a very simple question, which is about the conversation of the energy of moving objects (in terms of special relativity). As an example let's talk about firearms. If the mass of the gun M1 is infinitely higher...
  38. G

    B Casimir effect, energy conservation

    I was reading some articles about Casimir effect. It turns out that some virtual particles are created and suddenly disappears amd that these particles can exert a pressure on the plates. It seems that this creation breaks energy conservation law, but it cannot be.I would like to know which...
  39. Jamie_Pi

    Starting height of marble rolling around a loop the loop

    Homework Statement The marble rolls down a track and around a loop-the-loop of radius R. The marble has mass m and radius r. What minimum height h must the track have for the marble to make it around the loop-the-loop without falling off? (Use any variable or symbol stated above along with the...
  40. W

    By energy conservation, show the 4-velocity of dust satisfies this....

    Homework Statement Using conservation of energy, show that the 4-velocity ##u^{\mu}## of dust satisfies: ##u^{\mu}\nabla_{\mu}u^{\nu} = f u^{\nu}## Explicitly identify ##f##, which is some function of ##u^{\mu}##, ##\rho## and their derivatives. And show that this equation becomes...
  41. S

    I CPT Violation and Energy Conservation: Explained!

    Hello! I read that natural processes are invariant under CPT (based on some theorem) and that CP violation was observed experimentally. So this would mean that there are processes that are violated under time reversal. However, based on Noether theorem, this would mean that the energy is not...
  42. E

    SHM Energy Conservation in a Spring

    1. The problem statement, all variables, and given/known data Describe the energy conversions in a spring undergoing simple harmonic motion as it moves from the point of maximum compression to maximum stretch in a frictionless environment. Focus on points at which there will be maximum speed...
  43. A

    I Energy conservation concerns in the weak interaction

    I have a few questions: Can a u quark turn into a d quark (heavier) via the weak interaction? If so, how is the mass/energy shortfall made up? How can the (supermassive) carrier bosons (W, Z) be called into being? Where does the energy come from? Or is the energy bill unpaid because they are...
  44. O

    Energy Conservation: Puck on Wood on Frictionless Surface

    Homework Statement Hey all, another problem. There is a 1 meter wooden panel that is on a frictionless surface. A puck is placed on one end of the panel and is pushed towards the other side. The mass of the panel is 10 times that of the puck. Also, there is a friction coefficient of uk=0.15...
  45. C

    Energy conservation in a magnetron

    I am trying to understand how energy is conserved in a magnetron. If the electrons are following a circular path in the magnetic field and never reach the anode will there be zero current between the anode and the cathode? If so how does the device consume power from the external circuit...
  46. D

    Momentum of W Bosons After Collision in Particle Physics Lab

    Homework Statement In a particle physics lab, an electron e− and a positron e+ collide, annihilate, and produce a W+ boson and a W− boson. Just before the collision, the electron and positron have a total energy of E = 100 GeV each, with velocities pointing along the +x-axis and -x-axis...
  47. Bunny-chan

    Potential gravitational energy coordinate axis

    Homework Statement I know that potential gravitational energy is relative to the reference point that I decide to choose (like in the picture below). But then if, for instance, I set my reference point in the ceiling and my vertically down y-axis to be positive. What would the potential...
  48. D

    Permanent Magnets: Exploring the Source of Energy

    First off, I am new here, so please don't tear me apart too hard if I miss or misinterpret something, I'll cotton on eventually :D As I understand it, when a permanent magnet repels an oppositely charged object, such as another oppositely charged permanent magnet, no energy is technically being...
  49. R

    Minimum Kinetic energy of the hydrogen atom

    Homework Statement A hydrogen atom collides with another hydrogen atom at rest. If the electrons in both atoms are in the ground state, what is the minimum kinetic energy of the hydrogen atom such that the hydrogen atom at rest will have its electron in the first excited state after collision...
  50. D

    Energy conservation for a Newtonian fluid?

    Homework Statement ρ= density, vi = i-th velocity component, gi=i-th component of gravity vector, p=pressure, μ= viscosity, D/Dt = material derivative Homework Equations Continuity equation: div v = 0 The Attempt at a Solution
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