Perpetuum mobile - so call the perpetual motion machine which idea of creation concerns minds of people long ago. It is proved that it is impossible to make the perpetual motion machine since it would contradict the all-physical law of energy conservation.
Instruction
1. Imagine the process having the result production of some work, but not changing in no way other bodies. The mechanism realizing such process is called the perpetual motion machine of the first sort. The impossibility of creation of "perpetuum mobile" in this case results from the first law of thermodynamics.
2. The first beginning of thermodynamics is mathematically formulated so: Q = U(2) - U(1) + A(1-2), where Q - the amount of heat received by a system, U(2) - internal energy of a system at the end of process, U(1) - internal energy of a system at the beginning of process, A(1-2) - the external work made by a system.
3. So, the warmth received by a system is spent for commission of external work by it and increment of its internal energy ΔU = by U(2) - U(1).
4. Perpetuum mobile assumes the following conditions: U(1) = U(2) - internal energy of a system does not change throughout all process; Q = 0 - the system does not receive from the outside of any amount of heat.
5. If to substitute these conditions in the first law of thermodynamics, then it will turn out that A(1-2) = 0, i.e. the system does not perform external work. Thus, the impossibility of creation of the perpetual motion machine of the first sort is proved.
6. The perpetual motion machine of the second sort is a hypothetical thermal machine with efficiency 100%. It is supposed that such car can turn all warmth got from the thermal tank into a job.
7. The experimental data demonstrates that it is impossible to construct a perpetuum mobile of the second sort. Generalization of the skilled facts became a postulate of the second beginning of thermodynamics which speaks about impossibility of creation of the perpetual motion machine of the second sort. So far the investigations from this thermodynamic postulate did not find any experimental denial.