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. S

    Hard/Tricky Problem on Energy Conservation

    Homework Statement If the car is given an initial speed of 4.0 m/s, what is the largest value that the radius R can have if the car is to remain in contact with the circular tract at all times? See the attached file (named: car.pdf) for the drawing. Homework Equations PE=mgh ----> Formula for...
  2. jegues

    Why am I getting a negative? (Energy conservation)

    Why am I getting a negative!? (Energy conservation) Homework Statement 2kg block slides on a rough table with uk = 0.3, just before the block hits the spring V0 = 1.3 m/s. k = 120N/m. How far is the spring compressed? Homework Equations Ki + Us = Kf + Us - Eth The Attempt at a...
  3. jegues

    Energy conservation (potential, kinetic, spring)

    Hello again, The question and free body diagram as well as my attempt at the solution are all in the attached photo. Thanks in advance!
  4. M

    Ski Slope using Energy Conservation

    Homework Statement It's been a great day of new, frictionless snow. Julie starts at the top of the 60 degree slope shown in the figure . At the bottom, a circular arc carries her through a 90 turn, and she then launches off a 3.0--high ramp. How far horizontally is her touchdown point from...
  5. D

    How Do You Calculate Initial Velocity in an Elastic Collision Problem?

    I need help! Homework Statement A 44.0 g ball is fired horizontally with initial speed vi toward a 110 g ball that is hanging motionless from a 1.10 m-long string. The balls undergo a head-on, perfectly elastic collision, after which the 110 ball swings out to a maximum angle = 52.0...
  6. E

    Energy conservation in relativity

    I did a thought experiment for myself today to test whether energy is conserved in Lorentz transformations. I chose to consider three objects lying on a horizontal line. In object 2's rest frame, object 1 has a velocity of 0.600c to the left, and object 3 has a velocity of 0.600c to the...
  7. X

    Momentum & Kinetic Energy Conservation: 1kg Block & 2kg Block Collision

    A 1kg block is at rest on a horizontal frictionless surface touching the end of an unstretched spring of spring constant 200N/m. Tjhe other end of the spring is fixed to a wall. A 2kg block traveling at a speed v(initial)=4m/s collides with the 1kg block, and the two blocks stick together. I...
  8. N

    Energy conservation: Bullet-block collision

    Homework Statement A 2.30 g bullet embeds itself in a 1.6 kg block, which is attached to a spring of force constant 770 N/m. A) If the maximum compression of the spring is 5.40 cm, find the initial speed of the bullet. Homework Equations Step one: convert everything to kg and m Step two: 1/2...
  9. S

    Loop-the-loop potential energy and energy conservation

    Homework Statement a toy race car of mass m is released from rest on the loop-the-loop track. if it is released at a height 2R above the floor, how high is it above the floor when it leaves the track, neglecting friction? (the radius of the loop is R) Homework Equations E=K+U The...
  10. O

    Find coefficient of kinetic friction using energy conservation

    Homework Statement An object of mass 0.2 kg with initial velocity 4.8 m/s slides a horizontal distance of 3.0 m before coming to rest (final velocity is 0 m/s). What is the coefficient of kinetic friction on the surface? Homework Equations K + U - W(other) = 0 ...conservation of energy...
  11. R

    General Energy conservation question

    This isn't really a homework question, so I'm hoping I can just get a straight answer from someone (although it is related to questions). I realize that you can choose U = 0 anywhere you want in a gravity-related problem, ideally choosing a place where it is easiest to manipulate mgy values...
  12. T

    Compton Scattering - Energy Conservation

    Homework Statement Using conservation of relativistic energy and momentum, show that for Compton scattering from a free electron, the energy-angle formula for the electron is T=m_0c^2\frac{2\alpha^2cos^2\phi}{1+2\alpha+\alpha^2sin^2\phi} where T = kinetic energy given to electon...
  13. K

    Particle physics: energy conservation

    Hi, I've managed to get extremely confused; I feel like I'm getting told different things! I hope someone can just clarify this for me. If you have a reaction, say for example: p pion+ --> p p (where p is a proton) is it true that the rest mass afterwards must be less than the rest mass...
  14. X

    Finding velocity use energy conservation help

    A .145kg drop from sixth story building window. If each story is 2.5m tall, use energy conservation to find the rock velocity when it strikes the ground. (ignore air resistance) I have: mass .145kg h 2.5m each story 2.5m * 6 = 15m (total height) gravity 9.8ms^2 V=? I am confuse, what...
  15. N

    Relativistic Momentum and energy conservation

    Hello everyonea. I was studying special relativity and i got stuck on an example. Here it is:'to an observer,two bodies of equal rest mass collide head on with equal but opposite velocities 0.8c and cohere. To a second observer,one body is initially at rest. Find the apparent velocity of the...
  16. P

    Superconductors and Energy Conservation

    A classic problem in freshman electrodynamics is as follows: We have a capacitor (capacitance C1) charged up w/ charge Q, which means the energy in the system is: U_1 = \frac{Q^2}{2C_1}. We then disconnect the battery, and connect a second capacitor (capacitance C2) in parallel w/ the...
  17. N

    Energy conservation for virtual photon

    In introducing the concept of 'virtual photon',Halzen Martin writes (ch#1,P#7) "An ekectron emits a photon (the quantum of electromagnetic field) and as a result,recoils in order to conserve momentum.it is clearly impossible to conserve energy as well,so the emitted photon is definitely not a...
  18. scupydog

    Does Walking on Creaky Floorboards Consume More Energy Than Normal Floorboards?

    While just standing on creaking floorboard, i was thinking about where the energy came from to create the noise. I assume it came from me moving my mass over the creaky point, therefore do i lose more energy walking on creaky floorboards than just normal floorboards?
  19. W

    Barton's Pendulums - Energy Conservation

    Suppose we have two pendulums of equal natural frequency set up like a Barton's pendulums system (hung on a common string). If we oscillate one of the pendulums, the other will also oscillate due to resonance. Supposing it's an ideal system where there is no friction. If we release the...
  20. F

    Quantum tunneling and energy conservation

    The probability of finding the particle inside the wall is non-zero, What happen if we do find the particle is inside the wall, would that violate energy conservation? since total energy is smaller than the potential energy of the wall
  21. D

    Energy conservation and projectile motion

    Homework Statement A spring is pulled back and launches a ball. The ball flies into the air at a perfectly horizontal angle. How far will the ball go before it hits the ground? Variables for the FINAL equation are: ∆x - distance the spring is pulled back g - acceleration of gravity m - mass of...
  22. H

    Physics problem: energy conservation around loop

    I've been fooling with this problem for quite some time now and I'm not sure where I'm going wrong. Any help would be appreciated. Homework Statement The two problems below are related to a cart of mass M = 500 kg going around a circular loop-the-loop of radius R = 12 m, as shown in the...
  23. I

    Kirchhoff's First Rule - Electrical Charge / Energy Conservation

    Hi, I've read that Kirchhoff's first rule is a statement of electrical charge conservation. However, currents are electrical charge in movement, so isn't it possible to say that it also follows the law of conservation of energy? Thanks.
  24. Y

    Potential Energy and energy conservation in General Relativity

    This is a spin off from another thread ( https://www.physicsforums.com/showthread.php?t=310455&page=2 ) to avoid hijacking the original thread. DrGreg offered this expression for Potential Energy from the textbook "General Relativity" by Woodhouse: PE = m_o c^2*\sqrt{1 - 2GM/(rc^2)}...
  25. C

    Energy Conservation: Determining Forces on Particles

    1. I have to use energy conservation to determine the forces acting on the particles. 2. An isolated system consists of two particles of masses m1 and m2, whose position vectors in an inertial frame are x1 and x2 and velocity vectors are v1 and v2. The interaction of the particles can be...
  26. D

    Energy Conservation in an expanded 1D box

    I am fairly new to QM and am learning many of the basics right now. We were just discussing conservation of operators (energy, momentum, etc) and I recalled a problem proposed in my textbook about a 1D particle in a box of length L. at a time t, the box suddenly expands to t=2L, in which time...
  27. C

    Energy Conservation of an electron

    Homework Statement Determine the total energy of an electron traveling at 0.98 c A) 0.25 MeV B) 0.51 MeV C) 0.76 MeV D) 1.8 MeV E) 2.6 MeV Homework Equations KE = 1/2 mv^2 E=mc^2 (rest energy) The Attempt at a Solution I had found the velocity for an electron by 0.98 * 3.0...
  28. Y

    Superposition of radio waves and energy conservation law?

    Hey all! Now I'm working on wireless communication, not a physician. In many courses in ECE, we learn about principle of superposition of radio waves. But I have a stupid question which has been considered no wonder so far. There are two radio senders(S1,S2) and one receiver(R). Let's...
  29. J

    Energy conservation answer check

    Homework Statement A 1500kg rocket is to be launched with an initial upward velocity of 50m/s. In order to assist its engines, engineers will start it from rest on a ramp that rises 53 degrees from the horizontal. At the bottom, the ramp turns upward and launches the rocket vertically. The...
  30. D

    Is Momentum Conserved with Different Force Directions and Types?

    5) If there are no external forces acting on a system in the x direction, but there is an external force acting on the system in the y direction, then the y component of momentum of the system is constant. True False 6) If work is done on an object by only conservative forces...
  31. A

    Energy Conservation or Momentum?

    Homework Statement A package of mass m is released from rest at a warehouse loading dock and slides down a 3.0-h frictionless chute to a waiting truck. Unfortunately, the truck driver went on a break without having removed the previous package, of mass 2m, from the bottom of the chute. a)...
  32. E

    What is the Initial Speed of a Basketball Thrown to a Hoop?

    Homework Statement The problem A basketball player 2.00m in height throws the ball at a 40degree angle 10.0m from the basketball post and manages to get the ball through the net without it touching the backboard. If the height of the net is 3.05m from the ground, what is the initial speed...
  33. M

    Energy Conservation: Block & Spring

    Homework Statement An object of mass M = 4 kg slides from rest a distance d = 4 m down a frictionless inclined plane where it encounters a spring. It compresses the spring a distance D = 1 m before stopping. The inclined plane makes an angle q = 20° with the horizontal. Homework Equations...
  34. B

    Where Does the Lost Energy Go in Cosmological Redshift?

    This is my first time on physics forums, and I am glad to have the chance to participate. My questions have been asked many times by others, but after lots of research, including among these threads on physics forums, especially “hurk4” on Feb 14-07 and Will Kastens, I can find no definitive...
  35. C

    Energy conservation used to predict speed?

    Homework Statement I don't know if anyone can help me with this without having done the lab, but I thought I'd give it a shot. Ok, so I did a lab in my physics class where we used little rollercoasters to find the PE and KE of a marble at various heights and speeds. Here is the question in my...
  36. H

    Energy conservation for a relativistic doppler shifted pulse

    I am new to the field of relativity. I read the Lorentz transformation between different system of coordinates. I have a question. Let's suppose that we have a Doppler shifted pulse in frequency (time dilation). This pulse has the same amplitude as the pulse seen by a moving observer. That is...
  37. matt_crouch

    Can someone explain mass energy conservation?

    Im confused with mass energy conservation. i get that mass and energy are conserved but i don't understand how mass can become energy and visa versa.. can anyone help explain it to me in another way?
  38. J

    Energy conservation in relativity

    I have a question with regards to the increase in mass of an an accelerated object. I actually posted this question yesterday but couldn't find it, so maybe it didn't get through... Anyway, consider 2 large masses very far away from each other. This system has a certain gravitational...
  39. A

    Solving Angular Momentum & Energy Conservation for Velocity at Point A

    Homework Statement Hey guys. So I got this disk connected to a spring which is connected to a wall. A mass m hits the disk with a velocity v and sticks to it. The question is to find the velocity of m at point A. As you can see I used the conservation of the angular momentum to find...
  40. S

    Inelastic collision and Kinetic Energy Conservation

    1) A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together. What is the speed of the wreckage just after the collision? Relevant equations: m1v1 - m2v2 = (m1+ m2) vfinal My attempt: This is an inelastic collision because the...
  41. B

    How can the distance traveled by a particle experiencing a force be determined?

    Homework Statement A particle P of mass m , which is on the negative x-axis. is moving towards the origin with a constant speed u. When P reaches the origin , it experiences the force F=-Kx^2, where K is a positive constant. How far does P get along the positive x-axis? Homework...
  42. I

    Super quick question on spring and energy conservation

    Super quick question on spring and energy conservation! Homework Statement What does conservation of energy in equation form look like for spring? Homework Equations i know that [delta]K= k-k0 i know that [delta]Ug=mgh-mgh0 idk on [delta]Us= ... The s,g stand for subscripts...
  43. P

    Energy conservation with a projectile -

    Energy conservation with a projectile -- please help! Homework Statement A 2.0 kg projectile is fired with initial velocity components Vox= 30 m/n and Voy = 40 m/s from a point on the Earth's surface. Neglect all effects due to air resistance. A) What is the kinetic energy of the projectile...
  44. F

    Energy conservation in heating by irradiation

    Hi all! I've been thinking of something lately. When an atom absorbs an incoming photon, the atom must gain some momentum in order to conserve linear momentum, right? Sort of like a totally inelastic collision? This momentum corresponds to some amount of kinetic energy and thus a raise in...
  45. K

    Energy Conservation in Oscillatory Motion

    A 2.25-g bullet embeds itself in a 1.50-kg block, which is attached to a spring of force constant 785 N/m. If the maximum compression of the spring is 5.88cm find (a) the initial speed of the bullet and (b) the tie for the bullet-block system to come to rest I used: E = K + U =...
  46. A

    I violate law of energy conservation

    Let's say we have a helium balloon carrying total weight of 1 kg. We set up 2 stations. Pumping station on the ground and deflating station at certain height. We pump the balloon until it start to float up. We catch it at deflating station at height H. Now the energy we gain is potential...
  47. H

    Answer: Energy Conservation: Maximum Compression & Max Velocity

    Homework Statement A 10 kg vox slides 4.0 m down the frictionless ramp shown in the following link. It then collides with the spring whose spring constant is 250 N/m. a. What is the maximum compression of the spring? b. At what compression of the spring does the box have its maximum...
  48. M

    Black Holes & Energy Conservation: Balancing Act of Nature?

    Considering UNIVERSE as a system , then are the black holes the elements that are present in the system so that the energy of the system remains conserved ? Is there any information on how black holes came into existence ( is it a balancing act of nature ) ? Can (energy conservation)...
  49. A

    Energy Conservation and Friction

    Homework Statement A 2.00 kg is released on a 53.1degree incline, 4.0 m from a long spring with force constant 120 N/m that is attached at the bottom of the incline. The coefficients of friction between the package and the incline are static friction constant = 0.40, and kinetic friction...
  50. Loren Booda

    Energy conservation education and funding for the public

    How much does the American public know about or enable energy conservation? It seems to me that by far most effort of this kind is by industry and government. Has the informational drive to change public consumption through behavior been successful, or is the primary means the pocketbook...
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