How does energy transfer by heating occur?

Energy transfer by heating occurs from hotter to colder objects due to the second law of thermodynamics, which states that heat naturally flows in this direction. When two objects with different temperatures come into contact, the thermal energy will move from the object that has higher thermal energy (the hotter object) to the one with lower thermal energy (the colder object) until thermal equilibrium is reached. This process is fundamental in understanding energy interactions in everyday life, such as when a hot cup of coffee cools down or when ice melts at room temperature.

In contrast, energy does not transfer from colder to hotter objects spontaneously; this would require additional energy input to occur, thus violating natural thermodynamic laws. Similarly, energy transfer without a temperature change does not describe the heating process, as heating inherently involves a temperature difference facilitating the transfer. Lastly, while mechanical work can convert energy from one form to another, it is not how energy is transferred by heating, which is purely related to thermal interactions.