The perpetual motion machine you mentioned obeys the law of conservation of energy and is the second type of perpetual motion machine.
The second type of perpetual motion machine violates the second law of thermodynamics. Simply put, one is that the efficiency cannot reach 100% and the other is the unidirectional nature of the machine. energy transfer.
Let's take the example of your perpetual motion machine. Not all the energy supplied by humans can be converted into electrical energy, and some of it is converted into thermal energy. Thermal energy will be lost and cannot be lost. used.
There are two situations in a perpetual motion machine:
1. A certain substance returns to its initial state after a cycle and does not absorb heat but releases heat or functions. is called the “perpetual motion machine of the first type”. This type of machine does notWe consume no energy, but can carry out outdoor work continuously.
In Europe, one of the most famous early perpetual motion models was proposed by a Frenchman named Hennecaut in the 13th century.
As the picture shows: there is a rotating shaft in the center of the wheel, 12 movable short rods are installed on the edge of the wheel, and an iron ball is installed at one end of each short stem. stem. The system designer estimates that the ball on the right is further from the axis than the ball on the left, so the rotational torque generated by the ball on the right is greater than the rotational torque generated by the ball on the left. In this way, the wheel will rotate endlessly in the direction indicated by the arrow and cause the machine to rotate. This design has been copied by many people in different forms, but it has never achieved continuous rotation.
If you analyze it carefully, it will happen thate even though the torque generated by each ball on the right is large, the number of balls is small and the torque generated by each ball on the left is small, but the number of balls is large. Therefore, the wheel will not continue to rotate and do external work, but will only oscillate a few times and then stop at the position shown in the picture on the right.
Early in the development of thermodynamics, the mutual conversion of heat and mechanical energy was the subject of research. Driven by the industrial revolution, steam engines were widely used in industry and transportation. People are studying how to consume the least amount of fuel and get as much mechanical energy as possible. We even dream of building a machine that does not require energy from the outside world, but which can constantly perform work on the outside world. This is called the first type of perp motion machineetual. In order to solve this problem, people are encouraged to study the relationship between heat and mechanical energy. J.R. Mayer was the first to propose the law of conservation of energy, and this law was confirmed by the physics community after the publication of the experimental work of J.P. Joule.
Joule conducted a large number of experiments between 1840 and 1848 and determined the strict quantitative relationship between heat and different energies. In the past, the unit of heat was cal (calorie) and the unit of work was erg (erg). Joule's experimental result was 1cal=4.184×10^7erg, which is the famous equivalent of thermal work. After that, it was more accurately measured as 4.184×10^7erg, or 4.184J (Joule). The Joule experiment shows that all substances in nature have energy. It can have many different shapes, but with suitable devices it can be converted from one shape to another.re.The total quantity remains unchanged. The establishment of the law of conservation and conversion of energy brought a final judgment on the illusion of creating a perpetual motion machine. Therefore, another expression of the first law of thermodynamics is: “It is impossible to create a perpetual motion machine of the first type. ". We see that the first law of thermodynamics is the law of conservation and conversion of energy in the field of thermal phenomena.
2. A heat engine which absorbs the heat of a single heat source and completely transforms it into useful work without producing other effects is called the second type of perpetual motion machine
After the advent of the first law of thermodynamics, people realized. that energy could not be created from nothing So some people proposed designing a type of device that could absorb thermal energy from l.ocean, atmosphere and even thermal energy. the universe and convert this thermal energy into As the source of driving the rotation and work of a perpetual motion machine, it is the second type of perpetual motion machine.
The first Type II perpetual motion device in history was the zero motor designed by American John Gamge for the United States Navy in 1881. This device used the heat of seawater to spray liquid ammonia and propel it. However, this device cannot operate continuously because vaporized liquid ammonia cannot be re-liquefied without the presence of a low temperature heat source, so the cycle cannot be completed.
In the 1820s, the French engineer Carnot designed an ideal heat engine that operated between two heat sources: the Carnot heat engine. The Carnot thermal engine has theoretically proven that the operating efficiencyement of the heat engine is linked to the relationship. between the two heat sources depending on the temperature difference. The German Clausius and the Englishman Kelvin proposed the second law of thermodynamics after studying the Carnot cycle and the first law of thermodynamics. This law states that it is impossible to absorb heat from a single heat source and completely transform it into useful work without producing other effects. The promulgation of the second law of thermodynamics condemned the second type of perpetual motion machine to death, and one of the ways of expressing this law is: the second type of perpetual motion machine is impossible to realize.