Using hot water bags for heating is a kind of heat transfer.
Hot water bag can be used for heating, the temperature of the hand is low, the temperature of the hot water bag is high, the temperature difference exists, and the temperature can be transferred to the hands of low temperature
There are three ways of heat transfer: conduction, convection and radiation. The process of heat transfer is the transfer of energy
There are two ways in which an object can be changed: work and heat transfer
