Tutorial SPb: ITMO University, 2016. 32 s. The textbook was developed in accordance with the program of the course "Thermodynamics and Molecular Physics" of the Federal State Educational Standard of Higher Education for Bachelors in the direction of training 16. 03. 01 “Technical Physics” and the program of the course “Fundamentals of Thermodynamics and Molecular Physics” of the Federal State Educational Standard of Higher Education for Bachelors in the Field of Training 14. 03. 01 - "Nuclear Energy and Thermal Physics" . This edition includes lectures on polytropic processes of ideal gases. Isochoric, isobaric, isothermal and adiabatic processes, ideal cycles of internal combustion engines and cycles of air-jet engines are considered.