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Kinetic energy

  1. Jan 1, 2010 #1
    I feel that I don't comprehend kinetic energy fully. I am trying to figure out under what conditions would kinetic energy not be conserved using prinicples of physics. Can anyone help me understand this better. Please try and put it in laymans terms because this is all new to me. It will not be helpful if I can't understand what you are explaining to me. I really appreciate any help anyone can provide!!!!
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  3. Jan 2, 2010 #2


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    When you have friction, kinetic energy is not conserved. Some colliding objects don't conserve kinetic energy.
  4. Jan 2, 2010 #3


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    Also, have another look at the work-energy theorem. It states that the work done will be equal to the change in kinetic energy. If work is done...kinetic energy will change.
  5. Jan 4, 2010 #4
    How does this sound? I am not sure if this is correct

    kinetic energy can be changed to electrical energy using a generator,
    into heat energy using friction or inelastic collisions
    into electromagnetic radiation by striking certain crystals,
    into potential energy by lifting an object or compressing a gas.
  6. Jan 5, 2010 #5


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    Well these are true, not sure about the electromagnetic one though since I have not studied much about that.
  7. Jan 5, 2010 #6
    KE changes when an external force or torque is applied to a system. W=[tex]\Delta[/tex]KE=Fd for linear motion or =[tex]\tau[/tex][tex]\theta[/tex] for rotational.
  8. Jan 5, 2010 #7
    Could you explain this a little further?
  9. Jan 5, 2010 #8
    when a force acts on a system, KE is gained or lost (within the system at least, because energy is never destroyed). like friction. energy is lost in the forms of heat, sound, etc. and transferred to the surroundings. If you push an object from rest, exerting a force, it will gain velocity and, thus, KE. Torque is the same concept, but for rotational motion. I don't know how much you know about that, though.
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