Please explain Law of Conservation of Energy?
Peter Griffin asked:
I understand that energy is converted from one form to another and that the law of conservation of energy states that energy is not created or destroyed. However, I do not understand how energy is conserved if it seems to eventually dissipate. For example, when a top spins kinetic energy is not lost because it is transformed into thermal energy due to friction. When the top eventually stops and when the ground cools and everything seems to have reverted back to what it was before, how is energy still conserved?
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I understand that energy is converted from one form to another and that the law of conservation of energy states that energy is not created or destroyed. However, I do not understand how energy is conserved if it seems to eventually dissipate. For example, when a top spins kinetic energy is not lost because it is transformed into thermal energy due to friction. When the top eventually stops and when the ground cools and everything seems to have reverted back to what it was before, how is energy still conserved?
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October 30th, 2007 at 1:49 am
For the ground to cool, something else had to absorb the heat.
Ultimately all of the heat we create is radiated back into deep space.
October 31st, 2007 at 7:17 pm
The energy is dissipated into the environment as wasted heat never to be recovered again. This causes the ENTROPY (a measure of the disorder of a system) of the universe to increase. According to the 2nd Law of Thermodynamics, the entropy of the universe will always increase.
Since entropy gives information about the evolution of an isolated system with time, it is said to give us the direction of time’s arrow . If snapshots of a system at two different times shows one state which is more disordered, then it could be implied that this state came later in time. For an isolated system, the natural course of events takes the system to a more disordered (higher entropy) state
November 1st, 2007 at 12:40 pm
From the wording of your question I gather that the source of the confusion is that you assume that all energy is useful, which is not the case. The energy in a spinning top is kinetic energy, which is useful, so is the potential energy of a weight laying on a table. But the energy of molecular motion - heat- is useful only if it is concentrated, meaning, available at high temperature. When the top stops spinning its energy has dissipated to heat energy. Not to useful heat energy that can ignite a match, but to useless heat that has spread out in a heat sink at low temperature. The total amount of energy is the same - it’s conserved- but useful energy has been converted to useless energy. That’s another law, the second law of thermodynamics.
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Will the slug brain who keeps giving the thumbs-down please identify yourself? If you have an opinion, why don’t you express it openly? Better yet, do an honest calculation now and then to prove your point, although I doubt you know anything worth teaching anyone.