Lesson 2: Energy Transfers and Transformations – We learned that work is the transfer of energy that occurs when a force makes an object move in the direction of the force and work is only being done while the force is acting on the object. Next we discovered that energy transformations are inefficient because some energy is transformed to a form of energy that is not usable. We learned that a system can be open or closed. An open system is a system that exchanges matter or energy with the environment. A closed system is a system that does not exchange matter or energy with the environment.