77 calories is equivalent to 1 eggs, because the calorie of an egg is about 7 calories. Heat refers to the thermal interaction between the system and the outside world when the change of system state comes from the destruction of thermal equilibrium conditions, that is, when there is a temperature difference between the system and the outside world. As a result, energy is transferred from a high-temperature object to a low-temperature object, and the energy transferred at this time is called heat. Heat and work are two different forms of energy transfer that accompany the change of system state, and they are measures of different forms of energy transfer. They are all related to the intermediate process of state change, so they are not functions of system state.