What is the direction of heat flow?

• A. From warmer to cooler
• B. Equally in all directions
• C. Hot to cold
• D. Cold to hot

Answer: (C)

Heat moves from higher temperature to lower temperature. In practical terms, energy flows from a hotter object to a cooler one until both reach the same temperature. This directional flow holds across all methods of heat transfer—whether solids contact each other (conduction), fluids circulate (convection), or energy travels through space (radiation). Because a hot object has more molecular energy than a cold one, energy naturally leaves the hot body and enters the cooler surroundings. If both objects are at the same temperature, there’s no net heat transfer. So the statement that describes this natural direction—hot to cold—is the correct way to express how heat flows.