A thermos bottle with boiling water and sometimes a cork can bounce. Where does the energy to push the cork come from?
Boiling water, high temperature (heating expansion). In the thermos bottle, covered with plugs, boiling water is still expanding the air inside the bottle, so plug out(this process is the mechanical energy in which the inner energy is converted into a stopper.)
The air enclosed in it expands with heat, and the pressure in the bottle is higher than the outside. The plug rises when the pressure is enough to push the plug open
