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A wheel that spins forever; a bird that never quenches its thirst; a clock that never stops ticking, an endless source of free energy. These are but the dreams of inventors striving to make perpetual motion machines, machines that can work forever without any energy input. Are these machines possible without violating the laws of physics? No. Support Physics Girl videos → https://www.patreon.com/physicsgirl ‪http://physicsgirl.org/ ‪http://twitter.com/thephysisgirl ‪http://facebook.com/thephysic