What can boil water and make a hot air balloon fly into the sky?

Heat can boil water and make hot air balloons fly into the sky. Thermal energy is a form of energy. When other conditions of the material system remain unchanged, the increase of thermal energy leads to the increase of its temperature. From the molecular dynamics theory, thermal energy is the kinetic energy of molecular thermal motion. Water needs heating to boil, so does hot air balloon flight. Thermal energy, also known as heat and energy, is the energy of life. People's daily labor activities, sports, class study and other activities, as well as maintaining normal body temperature and various physiological activities, all consume energy. Just as a steam engine needs to burn coal, an internal combustion engine needs gasoline and an electric motor needs electricity.