Final answer:
Thermal energy is transferred from hot water in a tank to the surrounding air primarily through convection, which involves the movement of warm water rising and cooler water sinking. Radiation also plays a role in transferring heat as electromagnetic waves.
Step-by-step explanation:
The process by which thermal energy is transferred from the hot water in a copper hot-water tank to the surrounding air is known as heat transfer. This primarily happens through a process called convection, where the heat conducted to the water near the surface of the tank causes the water to expand and decrease in density, making it rise and exchanging the heat with cooler water that sinks, creating a convection current. Some heat is also lost through radiation, the emission of electromagnetic waves, which transfer heat to the surrounding air without needing direct contact.
As the heated water loses energy, the cooler water surrounding it is heated up, creating a continuous flow of energy from the water tank to the air. This is a fundamental principle of thermodynamics, where thermal energy flows from a hot object to a cooler one until temperature equilibrium is reached.