1001 Space Earth Nature History Human World Science and Technology Chemistry Materials Force and Energy Heat and Light Electricity and Magnetism Industry Machines Electronics and Computers Cars and Trucks Railways Ships Aircraft Fishing and Agriculture Undersea Exploration	Is it possible to make a perpetual-motion machine? No! A perpetual-motion machine would go on forever without needing energy. But machines have moving parts, which cause friction. Without extra energy to overcome friction, all machines eventually come to a halt. All machines eventually come to a halt!   Previous: Back Book: 1001 Section: Science and Technology Chapter: Machines