1. Lecture Eighteen Physics 100 Fall 2012  Conservation of Energy

2.  No Lab Tomorrow.  Lab WILL BE HELD Wednesday, Thursday and Tuesday of next week.  Second writing assignment due on 12/12/12  Exam 3 discussion

3.  An electric motor is a device that converts electrical energy into mechanical energy.  Electric motors use magnetic force to cause motion.

6. Get “mechanical” energy (motion) out Put “electrical” energy (electricity) in.

7. Put “mechanical” energy in to cause rotation Get “electrical” energy (electricity) out

8. Watt x hour or a kilowatt-hour is a unit of energy which can be converted into a Joule.

9. Because V=iR

10.  Kinetic energy (or mechanical energy) is energy associated with motion.  KE=½ mv 2 where m is the mass of an object and v is velocity or speed

11. Put “mechanical” energy in to cause rotation Get “electrical” energy (electricity) out

12.  Energy is not created or destroyed.  Rather, energy changes form (electrical to mechanical for example).  Or, is transferred from one object to another.

13.  Where did the energy come from to start with?

15.  Kinetic (mechanical)  Electrical  Heat  Light from the sun and other objects  Sound  Potential (stored): Chemical bonds including meat and plants, gravitational potential energy, springs, petroleum