### Unit 7: Work, Power, and Energy

 In this unit, we learned how to calculate work, power, potential energy, kinetic energy and thermal energy. Work and energy are scalar values, because they have only magnitude, not direction.  There are many different kinds of potential energy, but the one we focused on was gravitational potential energy. Gravitational energy is always measured relative to some reference point. We also learned that "energy cannot be created or destroyed, only changed from one form into another," this means that we cannot lose or gain energy, it only changes into something else. In the picture, the bicyclist on the left is pedaling up the hill. He has kinetic energy because he is moving (you have to have velocity in order to have kinetic energy). Same for the bicyclist going down the hill. He has kinetic energy because he has velocity. The bicyclist on the top has potential energy, because he has heighth. He has potential energy, meaning he has the "potential" to go down the hill and turn it into kinetic energy, get it?