Final answer:
Thermal energy transfer by way of convection is the movement of a fluid, caused by temperature differences, resulting in the circulation of heat. In the case of heating water in a metal pot over a campfire, the convection is observed as the heated water rises, while cooler water sinks to be warmed.
Step-by-step explanation:
The transfer of thermal energy by way of convection occurs when a fluid (such as water or air) is heated, becomes less dense, and rises, while cooler fluid moves in to take its place, creating a circulating flow. In the scenario where a camper heats water in a metal pot over a campfire for hot chocolate, convection would be represented by the movement of the hot water rising to the top of the pot, while the cooler water sinks to the bottom, creating a continuous circulation and even distribution of heat throughout the water.
Heat transfer by convection is very common in various cooking methods, including the example given where a barista steams cold milk to make hot cocoa. As the milk is heated from below, the bottom layer of milk expands, becomes less dense, and rises to the top, transferring heat through the rest of the milk. Similarly, within the metal pot over the campfire, heat conducted from the fire warms the water at the bottom of the pot, and this warmer water then moves upwards due to its lower density, allowing colder water to sink and be heated in turn.