Heat Transfer

So, in the article on Work, we defined work as a transfer of energy caused by a force acting along a displacement. Objects with temperatures have their own internal energies, or temperatures(basically). If you put two objects with different temperatures, they'll interact such that they reach a thermodynamic equilibrium. During this process, heat transfers from the hot object to the cold object. This is known as the Zeroth Law of Thermodynamic Equilibrium.

So, as told above, objects with different temperatures transfer energy between themselves, which means work is being done. But how? There isn't a force acting along a direction of motion. This gives rise to the concept of heat, which is defined as the spontaneous transfer of energy caused by a difference in temperature.

So now that we know about heat and how it comes from the fact that two objects have different temperatures, we can discuss the different ways heat gets transferred, as given by the links to the topics below:

Calorimetry

Conduction

Convection

Thermal Radiation