|MadSci Network: Physics|
Dear Hilda. This Idea is not feasible due to energy loss every time it changes its form, so we always need to input additional energy into the system. Still there is no such system exist in this world due to above reason and mearly not feasible. Good Luck [Note added by MadSci Admin: There are some previous answers in our archives which discuss the conservation of energy as it applies to the current question. Use the Google side of our search engine (http://www.madsci.org/search.html) to search on "conservation of energy" +losses including the quotation marks.]
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