In which scenario is forced convection most commonly observed?

Forced convection is most commonly observed when there is an external force used to enhance the movement of fluid or air, which helps in transferring heat. In the scenario where a fan is used to distribute heat in a room, the fan creates a forced flow of air. This movement increases the rate of heat transfer from the heating source to the air and subsequently to the surfaces and objects in the room, demonstrating the principle of forced convection effectively.

In contrast, the scenario of cooking food in a pot without stirring relies on natural convection, where heat causes the fluid to move without any mechanical assistance. The actions of inflating a balloon involve compressing air but do not involve heat transfer mechanisms like convection. Lastly, heating a solid object in the sun involves primarily radiation and conduction rather than convection. Therefore, using a fan to distribute heat clearly illustrates forced convection as it actively promotes fluid movement to enhance heat transfer.