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Q & A: stored energy

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Most recent answer: 03/18/2013
Q:
If a system gives out more energy than what was applied to it, there is no violation for the laws... There could be a stored potential that caused the additional work being done, from the work being applied to it. And how would anyone know if an object or system has stored potential? Only when the input is less than the output?
- Moe (age 19)
Fort Collins,CO,USA
A:
Pretty much any familiar system has some stored energy, whether or not the particular things you do to it happen to extract some of it. The most common form of stored energy is that the nuclei are not in their lowest energy state (some isotope of iron) but are instead in higher-energy light nuclei (e.g. carbon) or heavy nuclei (e.g. lead). Almost anything you do will not trigger nuclear reactions to release that energy, so we ignore it for most practical purposes.

Typical machines also have some stored chemical potential energy, in that if the machine burned up heat would be released. That's not usually what you want to do.

So if you get more energy out than you put in, you know that there was some reserve inside. If not, there probably also was some sort of reserve energy inside, just not one that you're getting at.

Mike W.

(published on 03/18/2013)

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