Question

isaac wants to make smores. he holds a marshmallow on a metal skewer over a fire. a few seconds later, the marshmallow is cooked and the skewer feels warm. what most likely happened?
the fire heated the surrounding air, which cooked the marshmallow.
the heat generated from the marshmallow flowed in the form of thermal energy to the skewer and fire.
the heat from the skewer cooked the marshmallow.
thermal energy in the form of heat moved from the fire to the skewer and marshmallow.

Explanation:

Heat transfer occurs from a hotter object to a cooler one. In this case, the fire is the source of heat (thermal energy). The metal skewer (a conductor) and the marshmallow (insulator to a lesser extent) receive heat from the fire.

• Option 1: While air can transfer heat (convection), the main heat transfer here is likely conduction through the skewer (metal is a good conductor). But let's check other options.
• Option 2: Heat flows from hotter to colder. The marshmallow is not the source of heat (it gets cooked), so heat does not flow from it to the skewer and fire.
• Option 3: The skewer is not the source of heat. The fire is.
• Option 4: Thermal energy (heat) moves from the fire (hotter) to the skewer (and then to the marshmallow as it is in contact with the skewer). This is in line with the principle of heat transfer from a higher - temperature body to a lower - temperature body.

Answer:

Thermal energy in the form of heat moved from the fire to the skewer and marshmallow.