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. O

    Solve following problems by using energy conservation theory

    Solve following problems by using energy conservation theory.. A car driving down a long hill. The engine is switched off, and the speed is constant. The hill has a drop of 1.00 m for each 25.0 m driven way. The car has mass 1020 kg. Calculate the total friction on the car. A cyclist...
  2. C

    Atom/photon energy conservation

    I wonder of someone could help me understand something about emission and absorption of photons by atoms. I thought I understood the basics of this topic but yesterday a thought experiment occurred to me that seemed to violate conservation of energy. Imagine two stationary hydrogen atoms. Atom...
  3. S

    Energy conservation in a vacuum bubble

    I'm a bit confused by vacuum "fluctuations" (I know there is nothing fluctuating since vacuum is lorentz invariant) and their interpretation/representation by Feynman diagrams. In a normal Feynman diagram, you have energy conservation at each vertex, so overall energy conservation is ensured...
  4. S

    Energy conservation in two dimensions

    In an experiment, one of the forces exerted on a proton is F = −αx^2i , where α = 14.4 N/m2. (a) How much work does F do when the proton moves along the straight-line path from the point (0.10 m, 0) to the point (0.10 m, 0.5 m)? (b) Along the straight-line path from the point (0.09 m, 0) to...
  5. A

    Hooke's Law & Energy conservation

    Homework Statement An engineer is designing a spring to be placed at the bottom of an elevator shaft. If the elevator cable should happen to break when the elevator is at a height h above the top of the spring, calculate the value of the spring constant k so that the passengers undergo an...
  6. D

    Rotational energy conservation

    Hi, I am a little confused about the energy conservation of a pin ended free falling rod. When i try to derive energy conservation equation i am not sure including angular and linear velocity at the same time. I try to visualize the problem in the attached picture and put my derivation also...
  7. N

    Problem with energy conservation of mgh and 1/2 kx^2 (spring)

    So I feel really stupid asking this, because this is a very elementary physics problem and I'm well past this level of physics, but I don't understand what's going on here. Say we have a vertical spring with spring constant 100N/m. A 100N mass is placed on top of it. This will cause the spring...
  8. G

    Mechanical engergy, energy conservation

    Homework Statement A 10-kg block is released from point A. The track is frictionless except from the portion between B and C which has a length of 3.0 meters. The block travels down the track, passes through BC and first collides with a small block (m=2kg), then they travel together and later...
  9. C

    What is the Total Energy of a System with Given Values of Mass and Length?

    Homework Statement see link for a picture of the situation, http://i50.tinypic.com/n5g3z5.jpg Homework Equations (1/2)mv^(2) , (1/2)k*l^(2) The Attempt at a Solution Total energy of the system at the given point of time is mv^(2)/2+kl^(2)/2 = 0.6*100/2+100*0.25/2 = 30+12.5 =...
  10. atyy

    Minimal Coupling Needed for Covariant Energy Conservation?

    Thanks. I started a new thread, because I've seen what seemed to me a contradictory claim in Carroll's GR notes (Eq 5.38) - he says diff invariance is enough to get covariant energy conservation. I've never understood whether Carroll's claims and the ones in these papers are really...
  11. A

    Simple harmonic motion energy conservation problem

    Homework Statement A mass m hanging on a spring oscillates vertically. If the equilibrium point of the oscillation is a distance d below the relaxed length of the spring and if the amplitude of the oscillation is A, what is the maximum kinetic energy of the oscillation?[b]2. Homework Equations...
  12. D

    Quick question on Newton's third law & energy conservation

    I have a quick question on Newton's third law. When a 100kg astronaut in space is holding a 100 kg rock and then pushes it away from him with 50 joules of energy (the kinetic energy put into the system) and a second astronaut (observer) is watching, sitting still relatively to the location...
  13. M

    How is Energy Conserved in a Mass-Spring System?

    Homework Statement Consider a mass connected to a spring of sti ness k. (a) Use conservation of energy to write down a first order differential equation obeyed by the mass. (b) Find the time t for the mass to move from the origin at t = 0 out to a position x assuming that at t = 0 it has...
  14. K

    Falling elevator energy conservation

    The cable of an elevator of mass M = 1640 kg snaps when the elevator is at rest at one of the floors of a skyscraper. At this point the elevator is a distance d = 36.4 m above a cushioning spring whose spring constant is k = 13600 N/m. A safety device clamps the elevator against the guide rails...
  15. Q

    How Does Friction Affect Energy Between Points B and C?

    A man who was first standing runs from the point A.His speed is 40 m/s in B and 23 m/s in C,where the distance BC=30 meters..a) What work does the force of friction over the man ( m=60kg)? b) Find the max height reached by the man in the C level.. image here http://i.imgur.com/HVd7UH2.jpg I...
  16. G

    Angular momentum and energy conservation.

    Homework Statement A mass m is laying on a frictionless table and is connected to a mass M with a nonelastic string going through the center of the table. At t=0 the m mass is at a r0 distance from the center of the table, and is moving at a v0 velocity in the tangent direction. Find the...
  17. D

    Energy Conservation And X-ray Diffraction

    I have a question regarding X-ray diffraction and energy conservation. If one considers elastic scattering from a rod-like structure, the observed diffraction pattern will change as the sample is illuminated from different directions. For some directions the pattern will be point-like, and...
  18. N

    Can magnets defy the law of energy conservation?

    I'm pretty sure it cannot, but if I put a common bar magnet close to another magnet, they will move towards each other. I don't have much of a background in physics, but it seems to me that the kinetic energy is coming out of...nowhere. I can repeat this experiment as many times as I like but...
  19. P

    Oscillator Equation - Energy Conservation

    Given the Oscillator equation: \frac{d2s}{dt2} + \omega2s = 0 Show that the energy: E=1/2(\frac{ds}{dt})2 + 1/2\omega2s2 is conserved. Any help at all appreciated! Thankyou
  20. J

    Solving Energy Conservation for Pendulum Movement

    Homework Statement Conservation of energy: looking for equations to solve the following Homework Equations A pendulum with length l = 0.50 m and with a negligible mass. The string is attached to a fixed point A and the pendulum swings in a vertical plane. The pendulum has a speed v = 2.15...
  21. S

    Rotational Motion: Energy Conservation

    Homework Statement the sliding block has a mass of .850kg the counterweight has a mass of .420kg , and the pulley has a mass of .350kg with outer and inner radius .030m, .020m, the coefficient of friction is .250. the pulley turns the axle. the light cord does not stretch and does not slip on...
  22. S

    How Far Will the Block Travel Up the Incline After Spring Release?

    Homework Statement Consider the following situation: A 2.0 kg block is placed against a compressed spring on a frictionless 30° incline. The spring of force constant 19.6 N/cm is compressed 20 cm and then released. How far up the incline will the block go before coming to rest? Homework...
  23. G

    Hydrogen atoms on collision (based on energy conservation)

    "Given a simple and violent chemical reaction { H + H → H2 + 5eV }. however when hydrogen atoms collide in free space they simply bounce apart. the reason is that it is impossible to satisfy the laws of conservation of momentum and conservation of energy in a simple 2 body collision which...
  24. O

    Energy Conservation in RLC circuit

    Homework Statement Assume the current in a series RLC circuit is given by I = ACω(sin(ωt) + \frac{α}{ω}cos(ωt))e^{-αt}. Calculate the energy stored in the circuit at t=0. Then calculate the energy stored in the circuit one-quarter cycle later, at t=\frac{\pi}{2ω}. Verfiy that the...
  25. S

    Energy conservation law violated(seems to be)

    the charge(say positive) in figure induces negative charge on the disc and positive on sphere, the net force on charge is attractive towards the disc and is a function of position, now if someone moves the charge the amount of charge on disc changes accordingly and force changes its magnitude...
  26. atyy

    Is energy conservation necessary?

    Must energy be conserved in a consistent Poincare invariant theory? It's not necessary in Newtonian physics. Are things different in special relativity?
  27. T

    Calculating Velocity for Energy Conservation in Rotating System

    Homework Statement In the image below, there are two balls of mass m attached to a massless rigid metal steam, which can rotate around the point A. Give the necessary velocity to be applied in the lowest ball for the system to reach the horizontal line. Do not consider any system's energy...
  28. D

    Understanding Energy Conservation in Laser Operation

    kindly help me understanding energy conservation in laser
  29. K

    Energy conservation for a point at the Earth's surface

    Hi everyone, This is my first post here and I am really sorry for that question, but I have found the answer nowhere. Consider a mass at the Earth's equator that is static in the Earth's referential during an entire day. Put the Earth at one of its equinoxes to simplify the problem. Then...
  30. S

    W/Z Bosons & energy conservation

    I recall watching a documentary a while ago that explained the production of different force carriers. A bit that stuck in my head was that (if I remember correctly) W and Z bosons were able to violate the law of energy conservation. The energy to create these particles was apparently...
  31. Ookke

    Kinetic energy conservation in matter/energy transform

    ... C1.... C2-> P-> In the above illustration, P is a particle, C1 and C2 are detectors able to measure the energy/mass of a light pulse. C1 is at rest, P and C2 move horizontally to right with the same velocity. Let's say that P is actually a matter-antimatter pair that annihilates to...
  32. Q

    Will the Sphere Reach Point C on Its Path?

    The sphere with the mass 1 kg is released from point A without initial speed and moves without friction just like in the figure. a) Find the mechanic energy in point A Solution : E=mgh because v=0 b) Find the kinetic energy in B Using the law of the conservation of mechanic energy...
  33. Q

    Energy conservation in the classically forbidden region

    Consider a particle approaching a finite potential step or inside a potential well. As we know, the particle has a finite probability to penetrate into the region where E < V. The probability remains finite arbitrarily deep into the classically forbidden region. Suppose we set a detector far...
  34. B

    Work and Energy Conservation, Need

    Homework Statement The spring in the figure has a spring constant of 1000 N/m. It is compressed 13.0 cm, then launches a 200 g block. The horizontal surface is frictionless, but the block's coefficient of kinetic friction on the incline is 0.220. What distance does the block sail through the...
  35. cepheid

    Michelson and Energy Conservation

    I'm wondering about the Michelson interferometer and energy conservation. It seems like if one arm has an optical path difference that results in a pi phase shift relative to the other arm, then there will be complete destructive interference at the output port. Talking to some people, I gather...
  36. C

    Energy conservation in electric field scattering from a discontinuity

    Hi, I'm a EE PhD student working a little bit out of my area, and have just gotten stumped trying to figure out the transient dymanics of a relativistic electron moving past a discontinuity. My little thought problem came up from wakefield interactions of a relativistic electron in a waveguide...
  37. P

    Violation of energy conservation?

    Hello, I have a question, which is kinda stupid probably, but I cannot solve it for myself. Hence the fancy title. Imagine you have a point mass m near a more massive object M. Let's say there is some other force supporting the point mass, so it can stand still at r = \vec{r_0}. Point mass...
  38. M

    Energy conservation in collisions

    I was curious, why is energy conserved in elastic collision but not in perfectly inelastic collision? It said this in my textbook without giving any reason why.
  39. Jalo

    What is the minimum value of b for a particle to stay on a circular rail?

    Homework Statement A particle of mass m starts his motion from rest in the top of a inclined plane. It slides down the plane and enters a circular rail of radius R. (a) What's the minimum value of b for the particle not to Uma partícula de massa m parte do repouso no topo de um plano...
  40. M

    Energy Conservation in Quark Confinement

    Hi guys, I was reading about quark confinement and came up with a doubt i can't find the answer to: You have to use energy to try to 'pull away' one of the quarks in a meson, right? And when you give enough energy, a new quark/anti-quark pair is created and that's why you never find only one...
  41. H

    Energy Conservation versus Quantum and Relativistic Effects

    A mathematical statement of energy conservation can be given using the continuity equation in terms of the total energy \frac{\partial}{\partial t}\iiint_V\epsilon dV+\iint_S \epsilon \mathbf{V\cdot dS}=0 where t is time, V is a velocity vector, V is the volume of the system, dS is a point...
  42. S

    What is the Speed and Angle of a Comet Crossing Earth's Orbit?

    Hey, here is the problem: The minimum distance of a comet from the Sun is observed to be half the radius of the Earth’s orbit (assumed circular) and its speed at that point is twice the orbital speed v(earth) of the Earth. The Earth’s and comet’s orbits are coplanar. Find the comet’s speed...
  43. N

    Energy conservation vs momentum conservation in SHM

    Homework Statement a mass M , attached to a horizontal spring executes SHM(simple harmonic motion) with amplitude A1 . when the mass M passes through its mean position then a smaller mass m is placed over it and both of them move together with amplitude A2 . the ratio A1/A2 is ...
  44. H

    Solving Momentum & Energy Conservation: Find Daughter Particle Velocities

    Homework Statement A particle of rest mass m moving with speed c/2 decays into two particles of rest mass 2m/5 each.The daughter particles move in the same line as the direction of motion of the original particle.Then what are the velocities of daughter particle? Homework Equations...
  45. A

    Energy Conservation Design Lab Idea

    Hello! Im working on a design lab but need a little help on making it simple enough to use materials you would find in a standard physics classroom. Purpose: To develop a testable question that examines the relationship between 2 variables governed by the law of conversation of Energy...
  46. L

    Rotational motion, energy conservation problem

    rotational motion, energy conservation problem URGENT please help Homework Statement A uniform rod of mass M=2 kg and length L = 2m is pivoted from its end. It has a point mass m=1 kg on its tip. It stars from rest at an angle of 30 degrees above horizontal. It falls under the influence of...
  47. J

    Does the conservation of energy apply to springs releasing objects vertically?

    This is just a concept question. Say you have a spring arranged vertically with an object on the end of it. The spring is compressed.. At some point you, the system is released from compression. When calculating the velocity at which the object loses contact, I understand that you use the...
  48. S

    Airfoil Induced Drag Energy Conservation

    Consider the production of lift only as the reaction force from displacing a mass of air downwards. No matter the mathematical abstraction (Bernoulli, circulation theory) this Newtonian explanation must hold true. So now imagine a rectangular wing in a wind tunnel where the wing spans the...
  49. M

    Energy conservation( system of masses)

    Problem and Data three masses conected m1= 800g, m2 =1100g m3=1200g. m2 rest on a table of coefficient μ=0.345. m1 and m3 hang vertically over frictionless/massless pulleys. The system is released from rest. Whats the velocity of m3 after falling 60.0cm P.S "i know this system can be...
  50. M

    Beam splitter energy conservation

    Hi, If we describe a beam splitter as follows: e^{ikx} -> \sqrt{T}e^{ikx} + \sqrt{R}e^{i\theta}e^{iky} e^{iky} -> \sqrt{T}e^{iky} + \sqrt{R}e^{i\theta'}e^{ikx} then \theta+\theta'=\pi is a condition to ensure conservation of energy according to my text. I tried working this out by taking...
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