Myth 1: perpetual motion machine and long-term operation are not equal signs! We can't deny that someone made a machine that can move for a long time and looks like a perpetual motion machine! But we must distinguish between "perpetual motion machines" and machines that can run for a long time.
"perpetual motion machine" refers to a system that can last forever, and those so-called "perpetual motion machines" can only be mechanized within a certain period of time. With the passage of time and the action of gravity and friction, these so-called "perpetual motion machines" will eventually stop moving!
Myth 2: No power is equal to no power! Many people think that the earth is a huge perpetual motion machine, because it has been running around the sun for billions of years. In the process of running, it is still doing work with the whole earth, and the earth does not consume any energy, so the earth is a perpetual motion machine!
This statement is obviously unscientific. For example, we take a rope and a stone is tied to one end of the rope. If we want the stone to move in a circle through the traction of this rope, we must provide a centripetal force to the stone, that is, we must consume energy by hand and then transfer it to the rope.
The same is true of the movement of the earth. As we know, the reason why the earth has been moving around the sun is because the sun provides it with a constant centripetal force, and the source of this energy is the gravity between celestial bodies. That is to say, the earth has a steady stream of energy input, and the sun is the power source, so the earth can't be a perpetual motion machine!
Myth 3: As long as the energy generated by your own movement can maintain your own movement, it is a perpetual motion machine! This statement itself is correct. If the work generated by the machine through motion can be converted into its own power, when this conversion reaches 100%, it can really be regarded as a perpetual motion machine. But this is impossible in real life!