In thermodynamics, heat is transferred energy that moves between substances or systems because of their temperature difference. According to the first law of thermodynamic and the law of energy conversion s a form of energy, heat is cannot be created or destroyed only moves from one form to other.
The stone gets heat energy from fire and moves this heat energy or thermal energy to water as it cools off and the water warms up. Heat moves or is transferred spontaneously from the hot stone into the cold water. Eventually, the stone and water have the same temperature and water becomes heated. At the time of heat flowing out of the stone into the water, the heat energy became less ordered, due to spreading out through both the stone and the water. This is a net increase in entropy which is the second law of entropy.
