Transcript: Thermodynamics is the name for the scientific study of the way heat flows. When materials of unequal temperatures come into contact heat will flow from the hotter to the cooler material. Isaac Newton was the first person to show that the rate of flow of thermal energy from a hotter substance to a cooler substance was proportional to the temperature difference between them. We’re all familiar with this. When we drop an ice cube in a glass of warm water heat is transferred from the water to the ice. The ice melts. The water surrounding it cools down. When you poor water from a hot kettle into a tepid bath the bath warms up, so the heat is spread from the boiling water in the kettle to the cooler water in the bath. When you touch a hot car in the summer sun and your finger burns it is because the heat is flowing from the hot car into your fingertip. These are all familiar examples, but we should remember that when we talk about heat flowing it is not like a substance or a liquid. What we are really talking about is the transfer of energy from the microscopic motions of the atoms or molecules moving at different speeds in hotter and cooler substances.