1. Section 3: Conservation of Energy

2. Where Does the Energy Go?
Introduction
Energy is not lost—it changes form
Where Does the Energy Go?
Friction—force that opposes motion
Example: Roller coaster converts energy
Uses some PE as…
Kinetic energy to move down tracks
Thermal energy created by friction

3. Energy is conserved within a closed system
Closed system—well-defined group of objects that transfers energy between on another
Example: Roller coaster system includes: track, cars, air
ME (PE + KE) converted to thermal energy, kinetic energy, and sound energy
Add together KE, thermal energy, sound energy at the end and it equals the same amount as the original amount of PE
Energy is conserved

4. Law of Conservation of Energy
Energy all conserved
Law of conservation of energy—energy can neither be created nor destroyed
Total amount of energy is always the same
Energy changes form but always adds up to the same as the initial PE
Example: Light Bulb System: outlet, wire, bulb
Electrical energy entering the light = total amt. of light + thermal energy
Energy is conserved

5. No Conversion Without Thermal Energy
Within a conversion always converts to thermal energy
Thermal energy due to friction not useful energy
Perpetual Motion? No way!
Perpetual Motion Machine—machine that runs forever without any additional energy
Does not exist only way is to have continual energy source

6. Section 4: Energy Resources
Energy resources—natural resource that can be converted by humans into other forms of energy
Sun—responsible for the most resources
Nonrenewable Resources
Cannot be replaced after they are used
Fossil fuels most important type

7. Fossil Fuels
Energy resources formed from buried remains of plants and animals
Example: coal, petroleum, natural gas
Sun’s energy converted by plants—energy used by animals that eat those plants
Coal—burned to produce steam run electrical energy
Petroleum—used for gas, kerosene, wax, synthetic fibers
Natural gas—used for heating; cleanest burning fuel

8. Electrical Energy from Fossil Fuels
Generate electrical energy by burning fossil fuels
Kinetic energy is converted to electrical energy by electric generator
Nuclear Energy
Nuclear energy generated from radioactive element (uranium)
Nuclear fission—uranium splits into two nuclei—considered nonrenewable resource

9. Renewable Resources Can be used and are replaced by nature Solar Water
Wind
Geothermal
Biomass—organic material that is burned to release energy

10. The two sides to energy resources
Depending on the location, purpose, amount of energy needed—some energy resources are better than others