query: Why can't we make a perpetual motion machine by using a magnet to pull up a piece of metal, then letting it fall back down?
positive_passages.docid: 82272
positive_passages.text: Why doesn't this magnetic perpetual motion machine work?
negative_passages.docid: 45613
negative_passages.text: Conservation of energy when slowing an object down
negative_passages.docid: 94234
negative_passages.text: Why isn't a metal pot a faraday cage?
negative_passages.docid: 136401
negative_passages.text: Violation of energy conservation in retarded interaction of magnet and coil
negative_passages.docid: 63700
negative_passages.text: Why doesn't an orbiting body keep accelerating?
negative_passages.docid: 48899
negative_passages.text: Is it possible to create matter?
negative_passages.docid: 59713
negative_passages.text: Why doesn't this perpetual motion machine using the buoyant force work?
negative_passages.docid: 22490
negative_passages.text: Does it take energy to move something in a circle?
negative_passages.docid: 135487
negative_passages.text: Why does the Earth not lose its magnetism?
negative_passages.docid: 35559
negative_passages.text: Vibration to Torque: Magic Motor
negative_passages.docid: 39132
negative_passages.text: Why is there a magnetic field around a magnet if there are no charges moving?
negative_passages.docid: 126558
negative_passages.text: The fate of a bar magnet released in an infinitely long copper tube
negative_passages.docid: 69753
negative_passages.text: Would it be possible for some to bend two elements?
negative_passages.docid: 35154
negative_passages.text: Can the Earth's magnetic field be used to generate electricity?
negative_passages.docid: 921
negative_passages.text: Can magnets rotate infinitely?
negative_passages.docid: 141144
negative_passages.text: Electrical Machines based on Electric Fields
negative_passages.docid: 120778
negative_passages.text: Is it possible to counter-act centrifugal force by moving at the same speed in the anti-spin direction?