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 Posted: Thu Aug 31, 2006 1:07 pm
Energy is subject to the law of conservation of energy (which is a mathematical restatement of shift symmetry of time). Thus, energy cannot be made or destroyed, it can only be converted from one form to another, that is, transformed. In practice, during any energy transformation in (macroscopic) system, some energy is converted into incoherent microscopic motion of parts of the system (which is usually called heat or thermal motion), and the entropy of the system increases. Due to mathematical impossibility to invert this process (see statistical mechanics), the efficiency of energy conversion in a macroscopic system is always less than 100%.
The first law of thermodynamics states that the total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system. In other words, energy is neither created nor destroyed, only converted between forms. This law is used in all branches of physics, but frequently violated for short enough periods of time during which energy can not be mathematically defined yet (see quantum electrodynamics and off shell concept). Noether's theorem relates the conservation of energy to the time invariance of physical laws.
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Posted: Thu Aug 31, 2006 1:23 pm
Potential energy is energy that is "captured" in an object, with the potential to be released. There are various different types of potential energy. Many of these – such as gravitational, elastic, or electrical potential energy – arise from the relative positions or configurations of objects. The potential energy may then be defined as the work that must be done against a particular force – in these examples, gravitational, electrical or elastic force – so as to achieve that configuration. Chemical potential energy is slightly different, at least in its macroscopic manifestation: it is the energy that is available for release from chemical reactions (for example, by burning a fuel).
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Posted: Fri Sep 01, 2006 6:18 am
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Posted: Fri Sep 01, 2006 6:18 am
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Posted: Fri Sep 01, 2006 6:19 am
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Posted: Fri Sep 01, 2006 6:23 am
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Posted: Fri Sep 01, 2006 6:24 am
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Posted: Fri Sep 01, 2006 6:30 am
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Posted: Fri Sep 01, 2006 10:23 pm
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Posted: Fri Sep 01, 2006 10:23 pm
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Posted: Fri Sep 01, 2006 10:24 pm
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Posted: Fri Sep 01, 2006 10:25 pm
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Posted: Fri Sep 01, 2006 10:26 pm
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Posted: Sat Sep 02, 2006 7:34 am
Oh! When you're down and looking for some cheering up
then just head right on up to the Candy Mountain Cave!
When you get inside you'll find youreslf a cheery land
such a happy and joyful and perky merry land!
They've got lolly pops and gummy drops and candy things!
Oh so many things that will brighten up your day!
It's impossible to wear a frown in Candy Town!
It's the Mecca of the Candy Cave!
They've got jelly beans and coconuts with little hats,
candy rats, chocolate bats! It's a wonderland of sweets!
Ride the Candy Train to town and hear the candy band!
Candy Bells! It's a treat as they march accross the land!
Cherry ribbons stream across the sky to the ground
turn around, it astounds! It's a dancing candy treat!
In the Candy Cave imagination runs so free!
So now Charlie will you please go into the cave?
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Posted: Sat Sep 02, 2006 11:50 am
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