definition of energy science
Now we can give our first scientific definition of energy: The energy of an object, or of a system, is how much work the object or system can do on some other object or system. In other words, energy measures the capability of an object or system to do work on another system or object.
Rather, energy refers to a condition or state of a thing. As we will discuss in more depth later, a book sitting on a table, for example, possesses energy (potential energy) because of its condition of being able to fall if nudged off the table.