In which direction does heat naturally flow according to the Second Law of Thermodynamics?

The Second Law of Thermodynamics states that heat naturally flows from hot substances to cold substances. This principle reflects the tendency of systems to move towards greater entropy, or disorder. When heat is transferred from a hotter object to a cooler one, the energy disperses, leading to a more uniform temperature distribution. This is evident in everyday experiences; for instance, when a hot cup of coffee is left in a cooler room, the heat from the coffee will dissipate to the surrounding air until thermal equilibrium is reached.

This natural flow occurs because systems naturally evolve towards a state that maximizes their entropy, meaning that energy will disperse and spread out rather than concentrating in one area. This principle underlines many processes in thermodynamics and is fundamental to understanding heat transfer and energy conversion in mechanical and thermal systems.