1. Chapter 1 Energy and Power Energy - the ability to do work; anything that can be turned into heat. Several forms: Kinetic KE = 1/2 mv 2 Heat is special form Potential (stored) Can be mechanical (spring), electro-chemical (battery), or electronic (energy stored in excited atoms) Gravity is special case PE = mgh Chemical bonds “Light” Mass (Einstein’s famous E = mc 2 )

2. Work, Energy, Power, and their units (Physics) Work = Force x distance Work and energy have same units Joules in metric Foot-pounds in English (seldom used) 1 Calorie = 1000 calories Power is the time rate of doing work or the time rate of gaining or losing energy Units of Power = Joule/sec = Watt So kWh is a unit of energy Energy Content Table

3. Alternative Energy: Gasoline, batteries, and fuel cells Gasoline is (relatively) cheap, but has problems… Unreliable and price may go higher Efficiency, pollution and greenhouse gas production So what’s wrong with batteries? Heavy and bulky Low energy per gram compared to gasoline Expensive to replace (especially ones with most energy/volume) Hybrids? Still problems with batteries Best with limited use of batteries (they last longer)

4. But the electric cars are coming! The Tesla RoadsterThe Chevy Volt

5. What’s all the hype about hydrogen? Not mined; made from water using hydrolysis Fuel cell creates water and electricity Lower energy/volume than gasoline Even when compressed (1/6 as much) or liquified (1/3 as much) Made from methane, but produces CO 2 BUT, hydrogen fuel cells produce no pollution, not even CO 2, so there may be conditions under which their use is justified. Just don’t expect a hydrogen car any time soon.

6. Have an eye on those tables! Page 1-12 Notice coal and natural gas vs. gasoline Page 1-16 Examples of energy units Page 1-18 Examples of power units These are really good sources of test questions!

7. Solar Power About 1 kW shines on 1 m 2 About 1 GW shines on 1 km 2 Take solar cell efficiency into account… 1 m 2 gives 150-400 W of electricity 1 km 2 gives 150-400 MW of electricity Use hydrogen storage for night energy? Solar cells are expensive and fragile

8. Kinetic Energy Killed the Dinosaurs Recall that KE = 1/2 mv 2 Fragment G: 1 km diameter 2000 kg/m 3 60 km/s 1000 Giga-tons of TNT