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ENERGY Energy Energy is the ability to do work. Kinetic Energy The energy of motion. The amount of kinetic energy a moving object has depends on its speed and mass. The faster something is moving, the more kinetic energy it has. Potential Energy The energy that an object has because of its position or shape. This rubber band has potential energy until it is flipped and then it has kinetic energy. Forms of Energy All energy involves either motion or position. Energy comes in several different forms: thermal (heat) energy, chemical energy, electrical energy, sound energy, light (radiant) energy, and nuclear energy. Thermal Energy Thermal energy is the heat energy that is created from moving particles. The faster the particles move, the more kinetic energy they have and the greater the object’s thermal (heat) energy is. Thermal Energy Particles of a substance that are father apart have more energy than particles of the same substance that are closer together. Thermal energy depends on the number of particles in a substance. Chemical Energy Chemical energy is the energy stored in a substance that can be released when the substance reacts during a chemical reaction. Ex. When wood is burned, chemical energy is released. Electrical Energy Electrical energy is the energy of moving electrons. Ex. when you plug in the radio, the electrons begin to move, energy is transferred to different parts of the radio and sound is produced. Sound Energy Sound energy is caused by an objects vibrations. Ex. when a guitar string vibrates, energy is transferred from the moving string to the air particles around it which transmit it from particle to particle producing sound. Sound Energy Light Energy Light energy is cause by the vibrations of electrically charged particles. Not all light can be seen – such as the light energy used to cook food in a microwave oven. Nuclear Energy Nuclear Energy is the energy caused by changes in the nucleus of an atom. An atom is the smallest particle into which an element can be divided and still remain that element. Nuclear Energy Nuclear energy can be created from the splitting of atoms (which store a lot of potential energy) and can be used to create electrical energy at nuclear power plants. Nuclear Energy Law of Conservation of Energy Energy cannot be created or destroyed, it is only changed into another form of energy. Energy Conversion An energy conversion is a change from one form of energy to another. This can also be called an energy transformation. Any form of energy can be changed into any other form. Often, one form of energy is changed into more than one form. Energy Conversion Example: Electrical Electrical Sound and Light Energy Efficiency Compares the amount of energy before a conversion with the amount of useful energy after the conversion. Mechanical Energy Mechanical Energy is the sum of an object’s potential and kinetic energy. Ex. A swinging pendulum’s mechanical energy is all kinetic (KE) at the bottom of its swing and all potential (PE) at the top of its swing. Energy Conversion Kinetic vs. Potential Energy Conversion The water behind the Hoover Dam has energy (Potential) because of its position relative to the planet earth, which is attracting it with a gravitational force. Letting water down to the bottom of the dam converts that energy into energy of motion (Kinetic). When the water reaches the bottom of the dam, it hits turbine blades that drive generators, and its energy of motion is converted into electrical energy. Energy Conversion Energy Resources Energy Resources An energy resource is a natural resource that people can turn into other forms of energy to do useful work. Types of Energy Resources The types of energy resources that we will be studying are: Fossil fuels, nuclear energy, solar energy, water (hydroelectric) energy, wind energy, geothermal energy and biomass energy. Non-Renewable Resources Non-renewable resources cannot be replaced after they are used up or depleted or they can only be replaced after thousands or millions of years. Ex. Fossil Fuels and Nuclear Energy Fossil Fuels Fossil fuels are formed from the buried remains of plants and animals that lived millions of years ago. The animals and plants stored energy from the sun and the energy is given off when fossil fuels are burned. Fossil Fuels Fossil fuels are the most important non-renewable resources. Examples: coal, petroleum / oil, and natural gas Fossil Fuels One way to generate electrical energy from fossil fuels is to burn the fossil fuels. This produces a lot of pollution and can be bad for the environment. Nuclear Energy Nuclear energy is considered a nonrenewable resource because it is created from the element uranium. Once the uranium is used up, no more can be created. Renewable Resources Renewable resources are used and replaced over a relatively short period of time. Example: biomass (trees, corn, waste products) Inexhaustible Resources Renewable resources that are in such large supply that they cannot be used up. Ex. Solar (radiant) energy, wind energy, geothermal energy, and hydroelectric energy. Solar Energy Solar energy is the sun’s rays (solar radiation) that reaches the Earth. Example: Sunlight can be changed into electrical energy through solar cells. Hydroelectric Energy Energy that comes from moving water. Hydroelectric Energy It is one of the oldest sources of energy and was used thousands of years ago to turn a paddle wheel for purposes such as grinding grain. Some people regard hydropower as the ideal fuel for electricity generation because, unlike the nonrenewable fuels used to generate electricity, it is almost free, there are no waste products, and hydropower does not pollute the water or the air. Hydroelectric Energy Because the source of hydropower is water, hydroelectric power plants must be located on a water source. Wind Energy Wind is caused by the uneven heating of the Earth’s surface by the sun. Since the Earth’s surface is made of very different types of land and water, it absorbs the sun’s heat at different rates. Wind Energy In the same way, the large atmospheric winds that circle the earth are created because the land near the earth’s equator is heated more by the sun than the land near the North and South poles. Today, wind energy is mainly used to generate electricity. Wind Energy A wind turbine changes the kinetic energy of the air into electrical energy by turning a generator. Wind is called a inexhaustible energy source because the wind will blow as long as the sun shines. Geothermal Energy Geothermal energy is heat from inside the earth. Example: groundwater moving over hotspots near the Earth’s surface can cause geysers. Geothermal Energy We use the steam and hot water produced inside the earth to heat buildings or to generate electricity. Geothermal energy is an inexhaustible resource because the water is replenished by rainfall and the heat is continuously produced inside the earth. Geothermal Energy Biomass Biomass is organic (living) material made from plants and animals. Biomass contains stored energy from the sun. Example: Dried cow manure can be made into plywood for building supplies and corn can be used to make ethanol which is a liquid fuel added to gasoline. Biomass Plants absorb the sun’s energy in a process called photosynthesis. The chemical energy in plants gets passed on to animals and people to eat them. Biomass is a renewable energy source because we can always grow more trees and crops and waste products will always exist. Ex. Wood, crops, manure and some garbage Energy Usage Energy Resources All energy resources have advantages and disadvantages….. See page 141 in textbook.