Chapter 9 Energy and Energty Resources
Conservation of Energy 9:3
Terms Friction- You should know this! Law of Conservation of Energy- energy can neither be created nor destroyed Closed system-a well defined group of objects that transfer energy between one another
Where Does the Energy Go? Work must be done to overcome friction Energy to do the work comes from the original potential energy When energy is used to overcome friction, some of it is converted into thermal energy Energy is not lost, it converts to another form.
Energy Is Conserved Within a Closed System Rollercoaster Example Consists of track cars and surrounding air Mechanical Thermal (due to friction) Mechanical Sound Kinetic energy at bottom of first hill Thermal energy due to friction Sound energy produced Original amount of potential energy Law of Conservation of Energy
No Conversion Without Thermal Energy Perpetual Motion Machine –A machine that runs forever The drinking bird –Not a perpetual motion machine –Use thermal energy in air to evaporate water from head
Energy Resources 9:4
Terms Energy Resource- a natural resource that can be converted by humans into other forms of energy in order to do useful work Nonrenewable resources- cannot be replaced after they are used or can be replaced only over thousands or millions of years Fossil fuels- energy resources that formed from the buried remains of plants and animals that lived millions of years ago Renewable resources- can be used and replaced in nature over a relatively short period of time
Nonrenewable Resources Fossil Fuels Most important nonrenewable resources Most common –Coal –Petroleum –Natural gas Contains stored energy from the sun Can be converted into electrical energy –See page 234 Nuclear energy-can be thought of as nonrenewable because there is a limited supply of needed elements
Renewable Resources Solar energy and wind energy considered almost limitless Solar Energy Water Energy Wind Energy Geothermal Energy Biomass See Advantages/Disadvantages chart page 237
Elements