Few energy transfer mechanisms

Here are some ways to transfer energy out of a system.

Work

This method¹ is by applying a force to the system and this results to a change in displacement in the point of application of the force. This is expressed by this simple equation:

$W = F \Delta x$

Heat

Heat² is the mechanism of energy transfer that is based on temperature difference of a system compared to its environment.

Mechanical waves

This method is described by traveling of a disturbance through a medium. For example is when the energy leaves from a speaker and the energy propagates through the air and this vibrations were detected by your ears which you perceive as sound.

Electrical transmission

This method which is very familiar in this century is when energy leaves the system in the form of electric currents.

Electromagnetic radiation

Electromagnetic waves such as light, x-rays, microwaves is transferring energy. A good example is the energy from the sun traveling to earth as light.