The conversion of energy from one form to another is called transformation of energy.

The application of inter-conversion of potential energy and kinetic energy can be described using a bow or an arrow.

When the archer pull the string with the arrow a small part of the muscular energy of the archer is transferred to the bow and is stored as the potential energy (here it is the elastic potential energy) of the bow. When the string is released the potential energy in the bow is transferred to the arrow as the kinetic energy of the arrow. The arrow shoots out with a certain velocity.