What is Energy conservation: Definition and 431 Discussions

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. trytodoit

    Impact of 2 rigid beam without energy loss has multiple slns

    Today, I discussed my friend about two rigid beams impact and assuming no energy loss in the impaction. As in the above figure, the upper beam move down with a uniform velocity ##v_c##, and hit a beam with ##0## velocity. After that the above beam will rotate and move away, which can be...
  2. 0

    Kinda silly, but what's the sign of v?

    I have a block with a certain mass attached to a spring. I pull it and then release. Spring pulls block back. When spring is back to its relaxed position, is the velocity of the block positive or negative? Exercise does provide k, mass and x, but that's not where the error is comming from...
  3. J

    Calculate muon speed after collision

    Homework Statement Two equal energy photons collide head on and annihilate each other, producing a u+, u- pair. The two particles have equal mass, about 207 times the electron mass. A) Calculate the maximum wavelength of the photons for this to occur. B) If the wavelength calculated in A) is...
  4. AlanKirby

    Do all exchange bosons violate energy conservation?

    Hi, so my question is along the lines of the following: Since the strong and EM forces are mediated by massless exchange particles, due to Heisenbergs uncertainty principle these forces are long range. Well, ok. But the weak force is mediated by W and Z bosons which are massive hence they can...
  5. tg85

    Neutral particle oscillation and energy conservation

    I have question that I've been thinking about for some time now, and that I can't get my head around. I an experimentalist without education in quantum field theory, and my quantum mechanics introduction courses were a long time ago, so bear with me please. As far as I understand, neutral kaons...
  6. K

    Conservation of Energy - Max height WITH Air resistance

    Homework Statement A ball (m=0.7kg) is dropped from a height (h=30m). The air resistance force is given by the formula F=kv^2 where k=0.0228 and v is the ball's speed. The ball bounces after a perfectly elastic collision. Calculate the maximum height the ball reaches after the collision...
  7. W

    Constructive interference and energy conservation

    Hi. Let's say two monochromatic laser beams superimpose in a single point in space in such a way that there's constructive interference. Because there's constructive interference there, the total intensity at that point will be larger than the sum of the separate intensities. Will this mean...
  8. H

    A slight confusion regarding dark energy & energy conservation

    I know there has been a lot of threads on the forum about this topic, but my question is slightly different from the others. I have recently read this article by Sean Carroll (http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/); now, I'm completely aware (& convinced)...
  9. Alexandre

    Is this correct second order approximation?

    I have a second order differential equation of the form (theta is a function of time): \theta ''=F\left(\theta ,\theta '\right) Turning them to two first order equations I get: \begin{cases} \theta '\:=\omega \\ \omega '=F\left(\theta ,\omega \right) \end{cases} And here's the algorithm...
  10. T

    Minimum Speed for Balsa Cube Tipping Problem

    A solid balsa cube of side length L = 16.0” and mass M = 8.60 kg is at rest on a horizontal table top. It is constrained to rotate about a fixed and frictionless axis, AB, along one edge of the cube. A bullet of mass m = 50.0 g is fired with speed v at the other side of the cube, at height a =...
  11. A

    Energy conservation in Special Relativity

    Homework Statement A train is traveling in the x direction at a speed of v. On the train, a passenger is playing darts and fires a dart in the y direction with a speed of Uy. The dart hits the target and stops abruptly. What is the difference in the mass of the dart as observed by a person on...
  12. arpon

    Energy conservation and periodic motion

    Homework Statement Four weightless rods of length ##l## each are connected by hinged joints and form a rhomb (Fig. 48). A hinge A is fixed, and a load is suspended to a hinge C. Hinges D and B are connected by a weightless spring of length ##1.5l## in the undeformed state. In equilibrium, the...
  13. L

    Blocks attached with spring is released from rest

    1. Consider the situation shown in figure. Initially the spring is unstretched when the system is released from rest. Assuming no friction in the pulley, find the maximum elongation of the spring. https://drive.google.com/file/d/0B3FvaDRwJ2neQWtBU3JrazVTeEU/view?usp=sharing Homework...
  14. 1

    Angle of photon emission from particle decay (Particle Phys)

    Homework Statement a) Particle A decays at rest into two photons. Calculate, in terms of the rest mass of A, the energy and momentum of each photon. b) In a different reference frame, particle A is initially in motion such that its kinetic energy is equal to its rest energy. Find the momentum...
  15. S

    Conservation of relavistic energy

    Problem statement, equations, and work done: A particle called a Kaon is moving at 0.8c through a detector when it decays into two pions. Kaon particle: mass = 493.7 MeV/c^2 Pion+: mass = 139.6 MeV/c^2 Pion0: mass = 135.0 MeV/c^2 1) Apply conservation of momentum/energy to determine the...
  16. D

    Tire stuck in mud - energy conservation

    Rg. Without air resistance, show the maximum height snow can reach is h_max=R+v^2/(2g)+gR^2/(2v^2) Solve using conservation of energy How do I start this problem? I assume all the initial kinetic energy ((mv^2)/2) from the spinning of the tire is translated to the gravitational potential energy...
  17. S

    Revolution of Planets: Rotation & Revolving Around Stars

    How do planets continuously rotate on their axis or revolve around stars ? Do the energy they consume for this continued motion gets expelled as heat ?
  18. mukul

    Adiabatic effusion and violation of energy conservation

    when the gas effuse out of an insulated container, its velocity is given by \sqrt{\frac{2\gamma RT}{(\gamma-1)M}} (irodov's problem 2.42) This leads to the result that every mole of leaking gas has an energy of \frac{\gamma RT}{(\gamma-1)} whereas we know the energy contained in 1 mole of gas...
  19. HaLAA

    How Fast Must the Boat Travel to Clear the Shark Tank Stunt?

    Homework Statement You've taken a summer job at a water park. In one stunt, a water skier is going to glide up the 2.0-m-high frictionless ramp shown, then sail over a 5.0-m-wide tank filled with hungry sharks. You will be driving the boat that pulls her to the ramp. She'll drop the tow rope at...
  20. J

    Maximum kinetic energy of a Pion produced via a kaon decay

    Homework Statement A possible decay mode a of a positive Kaon in the production of three Pions as shown below:. K+ → π+ + π+ + π− Whats is the maximum Kinetic energy that anyone of the pions can have? The kaon is a rest when...
  21. W

    An experiment question: Rotational Motion

    Homework Statement I am doing the rotational motion experiment with a rotary disk that has three spindle sizes. A string goes around the spindle and is connected to a hanger. I calculated my ratio as a percentage of total final KE to decrease in potential energy and it comes out to be around...
  22. G

    Energy Conservation applied to Earth's surface

    Homework Statement With what initial speed must an object be projected vertically upward from the surface of Earshot rise to a maximum height equal to Earth's radius? (neglect air resistance.) Apply energy conservation. Homework Equations ##E_{k_1}+E_{g_1}=E_{k_2}+E_{g_2}##, however since...
  23. P

    Exploring the Larmor Formula and Energy Conservation for Electrons

    Homework Statement In classical electromagnetism, an accelerated charge emits electromagnetic radiation. In non-relativistic limit, where the velocity of the electron is smaller than c, the total power radiated is given by the Larmor formula, to wit P=2/3*e2*a2/c3, where a denotes the...
  24. minimario

    Waterslide and Energy Conservation

    Homework Statement Homework Equations Conservation of energy, F=ma The Attempt at a Solution (a) By the conservation of energy, we use points A and C as the initial and final, ## \frac{1}{2} m v^2 - \frac{1}{2} m 2.5^2= (m)(g)(9.76) \Rightarrow v = 14.1 m/s ## (b) Since ## W_{nc} = \Delta...
  25. G

    Violation of energy conservation law?

    There are two disks of the same size and mass. A 5N force acts through the center of the first and another 5N force acts through the bottom of the other. The forces both point to the right. According to what I have learned, the linear momentum of both objects will be the same, but the second one...
  26. S

    Weightlessness in Space: Understanding the Concept and Its Effects on Astronauts

    Homework Statement If two bodies, each of mass M and radius R, initially r (r>>>R) distant away from each other start approaching each other with negligible speed then what is their speed which they collide?? Homework Equations The Attempt at a Solution initial energy,IE = (-G m^2) / r final...
  27. T

    Is energy conservation violated in this system?

    Energy conservation violation First of all, I would like to say that this model is NOT a perpetual motion. It will stop eventually. What I want to say here is that the output useful work seems to be greater than input energy My system consists of 2 elements. Each element is a cylinder put on...
  28. X

    Pendulum Speed at Different Heights

    Homework Statement The pendulum shown (http://puu.sh/chwMZ/90f4b96fb1.png ) swings freely, turning around at a height of 10 cm above the lowest point in its swing. It has an unknown mass, but air resistance can be ignored. a) Use energy conservation to find its speed at the lowest point of...
  29. M

    Maximizing Height Above Circle Center with Energy Conservation

    Homework Statement Use energy conservation to answer the following question. A mass is attached to one end of a massless string, the other end of which is attached to a fixed support. The mass swings around in a vertical circle as shown. Assuming that the mass has the minimum speed necessary at...
  30. S

    Energy Balance Spring Slider system

    I am currently looking facing a problem concerning a spring slider system. The system consists of a electro engine that pulls on a spring with a constant velocity. The spring is attached to a block that sticks to the surface, but after a certain force is applied (by the spring) starts to slip...
  31. B3NR4Y

    Energy Conservation and Coefficient of Restitution

    Homework Statement A 1300-kg car is backing out of a parking space at 5.0 m/s . The unobservant driver of a 1700-kg pickup truck is coasting through the parking lot at a speed of 3.2 m/s and runs straight into the rear bumper of the car. (a). What is the change in internal energy of the...
  32. andrewkirk

    Energy conservation in a FLRW spacetime

    Consequences of Energy conservation in a FLRW spacetime This entry uses the local energy conservation law to derive an equation that can be used, together with the Einstein field equation, to derive Friedman's equations for the dynamics of a homogeneous, isotropic universe. The energy...
  33. M

    Signal Processing energy conservation

    Homework Statement Two receivers, d=5 [meters] apart, are recording an air wave signal. The air wave travels in v=330 [m/sec] and coming from one side of the receivers. The air wave contains all the frequencies between 10 [Hz] and 200 [Hz]. a) If we sum up the recorded signal from the...
  34. B

    Is Energy Conserved When Changing Frames of Reference in Space?

    Of course I am sure this is not a paradox but rather a problem in my understanding of the situation. But this question is bogging me, and I haven't found a satisfying explanation yet. Suppose you are floating in space, in an inertial frame. An object much more massive than you is moving with...
  35. V

    Energy conservation of a rod in free space

    Hey everyone, A meager pea brain (me) is in need of some help from you fine physics gentlemen. This is a concept I've spend a lot of time pondering on (more than I would like to admit). Imagine a rod of uniform density in free space. If you apply impulse onto the center of mass then it...
  36. D

    Energy conservation, and conservative forces?

    What is the relationship of conservative & non-conservative forces to the conservation of energy? What differs with the two? Energy in each case...?
  37. P

    Question on Energy conservation - Car pushing on air column

    Question on Energy conservation -- Car pushing on air column Homework Statement An automobile moving through the air causes the air velocity to decrease and fill a larger flow channel. An automobile has an effective flow channel area of 3 m^2. THe car is traveling at 90 k/h on a day when the...
  38. P

    Can Magnets in Equilibrium Defy Energy Conservation Laws?

    If three circular or ring type magnets are placed such tnat centeral magnet is having its center at origin and other two are placed at its aperture repeling each other but they are just at enough distance such that the whole system is in equillibrium, placed on surface having friction. If i...
  39. P

    Questions about course of Energy conservation

    Thank you for helping me 1- One end of a rubber band is tied down and you pull on the other end to trace a complicated closed trajectory.If you were to measyre the elastic force F at every point and took its scalar product with the local displacement F→*r→,and then summed all f these . What...
  40. F

    Energy conservation paradox for constrained mass

    Consider the following setup (see illustration above): a mass m is connected to a circular section of a rail by means of a rod (with negligible mass) of length r, where r is the radius of the rail. The connection point P of the rod can move frictionless along the rail but is mounted such that...
  41. M

    Gravitational Force & Energy Conservation

    When Earth pulls a mass with gravitational force why does the energy of the earth-mass system decrease? Isn't work just transfer of energy meaning constant overall energy?
  42. M

    Basic question about energy conservation

    Hello I just read this http://io9.com/scientists-just-created-some-of-the-most-powerful-muscl-1526957560 where they explain a new type of revolutionary artificial muscle. The principle of operation is very simple: when a material gets hotter, it contracts and generates a force. I already...
  43. D

    Energy conservation - maximun height and equilibrium height

    Homework Statement A ball of mass M = 0.320kg is connected by a light but rigid rod of length L = 0.770m to a pivot and held in place with the rod being vertical. A wind exerts a constant force F to the right on the ball. The ball is released from rest, and the wind makes it swing up to a...
  44. H

    Energy conservation of a light spring

    Homework Statement A light spring is fixed to the bottom of a vertical tube.A ball is released from rest at a height h above the upper end of the spring as shown.After rebounding several times the ball eventually comes to rest and stay on top of the spring.Assume all contact surfaces are...
  45. S

    Energy conservation in identical destructive interference.

    Here's a thought experiment : Two identical spherical waves exactly 180 degrees out of phase destructively interfere throughout all of space. Is the energy contained in them just lost ?
  46. T

    Maximizing Energy Conservation in Particle Motion on a Helix Wire

    Homework Statement A particle P is free to slide on a smooth wire which has the form of a helix, with a position vector given by: r((t)) = a cosθ(t)i + a sinθ(t)j + bθ(t)k The particle is released from rest at the point (a, 0, 2∏b). Using energy conservation for conservative...
  47. C

    Energy Conservation Spring Pulling Mass Up Incline Plane

    Homework Statement http://imgur.com/xIckJqW A block of mass m rests on a plane inclined at an angle θ with the horizontal. A spring with force constant k is attached to the block. The coefficient of static friction between the block and plane is μs. The spring is pulled upward along the...
  48. 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...
  49. 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...
  50. 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...
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