In Unit 4, we began our journey to understanding energy. We discussed the fact that energy is the ability to do work. We defined work as moving an object over a distance against a force. We defined power as the amount of work done over time. We also defined a few of the common energy units: the Joule, calorie, horsepower and Watt. We covered some confusing stuff, but don’t feel bad if you’re having trouble with it. It takes a while for this to sink in. In this Unit 5, we’re going to talk about the two main categories of energy: potential and kinetic. We will talk about transfer of energy and we will also discuss conservation of energy and energy efficiency.