Adevice that changes thermal energy into mechanical energy

 A device that changes thermal energy into mechanical energy is the automotive engine. It converts thermal energy into mechanical energy or power to produce force and motion.

During combustion, when the gasoline burns, thermal energy is released. The engine converts this thermal energy into mechanical energy . Mechanical energy provides movement. The heat, expansion and pressure during combustion all supply thermal energy within the combustion chamber.

This thermal energy is converted to mechanical energy as the piston is pushed downward in the cylinder with great force.