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Q & A: modern energy

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Most recent answer: 10/22/2007
Q:
How was energy found? I mean a long time ago people didnít know that there was energy.
- Mande Le
Brisbane, Queensland, Australia
A:
The word energy has been around a long time, but the modern ideas about it really started in the 1800ís, with the work of Mayer, Joule, Helmholtz, Kelvin, and others. The key to the modern ideas is that energy is conserved. That is, we can look at phenomena and write down a bunch of numbers representing different things we call energy, and that some wonít change even though the terms do. For example when a ball drops, its gravitational energy (which depends on height) converts to kinetic energy (which depends on speed). You can find a lot about the development of the idea of conservation of energy, also called the 'first law of thermodynamics', from a simple web search.
Again, the key point is not that various things get called energy, but that we have some real rules about how those things behave.

Mike W.

(published on 10/22/2007)

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