External work done will cause a increase in GPE, Elastic PE, Electric PE , KE or Heat. This word external means a force applied to the system. If you carry an object upwards, the force that you apply is the external force and the work you do in carrying the object produce an increase in GPE. If the object falls down then work is done by the g field and work is done by the system hence decrease in GPE. This same concept can be applied to Electric potential energy. It may also be the case that KE loss = increase in PE where there is an exchange of energy without work.
Here is a scenario:
A space rock entering the Earth atmosphere at constant speed as it impact the surface of the Earth. Explain how is these possible taking into account the energy changes?
Consider energy exchanges, As the space rock fall there is decrease in GPE and there is no increase in KE because work is done against air resistance as the rock enters the atmosphere.
