Energy transformations (1)


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Energy transformations (1)

  1. 1. 1
  2. 2. Changing Forms of Energy Chemical, thermal, radiant, and electrical are some of the forms that energy can have. In the world around you, energy is transforming continually between one form and another. 2
  3. 3. Changing Forms of Energy Forest fires are a dramatic example of an environmental change that can occur naturally as a result of lightning strikes. 3
  4. 4. Tracking Energy Transformations As the mountain biker pedals, his leg muscles transform chemical energy into kinetic energy. Kinetic energy of his leg muscles transforms into kinetic energy of the bicycle as he pedals. 4
  5. 5. Tracking Energy TransformationsSome of this energytransforms into potentialenergy as he moves up thehill.Also, some energy istransformed into thermalenergy.His body is warmerbecause chemical energy isbeing released 5
  6. 6. Tracking Energy Transformations Because of friction, the mechanical parts of the bicycle are warmer, too. Thermal energy is almost always produced by an energy transformation. 6
  7. 7. Tracking Energy Transformations Because of friction, the mechanical parts of the bicycle are warmer, too. The energy transformations that occur Thermal energy is almost when people exercise, when cars run, always produced by an when living things grow and even when stars explode, all energy transformation. produce thermal energy. 7
  8. 8. Law of Conservation of Energy Energy is never created or destroyed. The only thing that changes is the form in which energy appears. Example: When the biker is resting at the summit, all his original energy is still around. Some of the energy is in the form of potential energy, which he will use as he coasts down the hill. Some of this energy was changed to thermal energy by friction in the bike. Chemical energy was also changed to thermal energy in the biker’s muscles, making him feel hot As he rests, this thermal energy moves from his body to the air around him. No energy is missing--- it can all be accounted for. 8
  9. 9. Potential energy is converted into kinetic energy.  Before the yo-yo begins its fall it has stored energy due to its position. At the top it has its maximum potential energy. As it starts to fall the potential energy begins to be changed into kinetic energy. At the bottom its potential energy has been converted into kinetic energy so that it now has its maximum kinetic energy. 9
  10. 10. Potential energy is converted into kinetic energy.A waterfall has both potentialand kinetic energy. The waterat the top of Bridal Veil Fallshas stored potential energy.When the water begins to fall,its potential energy ischanged into kinetic energy. 10
  11. 11. Energy Changes Form A car engine burns gasoline, converting the chemical energy in gasoline into mechanical energy. Solar cells change radiant energy into electrical energy. Energy changes form, but the total amount of energy in the universe stays the same. 11
  12. 12. Energy Changes Form Hybrid cars that use an electric motor and a gasoline engine for power are now available. Hybrid cars make energy transformations more efficient so the car can travel farther on a gallon of gas. 12
  13. 13. Energy Changes FormYou wake up. Its a cool, sunny day, Youthink youll go for a bike ride. But first youeat a good healthy breakfast. You aretaking the chemical energy stored in foodinto your own body. Any time energy isstored, its called potential energy. Itsavailable for later use. Without yourneeding to think about it, the cells in yourbody will break down the chemical bondsin the food and release the energy inthose bonds. Youll use the energy to staywarm, to grow, to keep your internalorgans working, and to move yourmuscles. 13
  14. 14. Energy Changes FormAnd you are moving. You jump upfrom the table, grab a jacket, headout the door. You hop on yourbicycle.The energy of motion is calledkinetic energy. As you pump yourlegs, the bicycle starts to roll. Yourkinetic energy is being transferredto the bicycle. 14
  15. 15. Energy Changes Form Back at home, you turn on a radio It runs on electrical energy which travels along thewires that connect a power plant to your home. The electrical energy used by the radiois converted into sound energy. Sound is another form of kinetic energy--its air in motion. You can move your musclesto make sound too. For example, you can hit a drum, sing or shout, or strum on aguitar. The guitar strings, vocal cords, or drumhead, once set in motion, make the airaround them move. 15
  16. 16. BIOMASS -- ENERGY FROM PLANT AND ANIMAL MATTERBiomass is organic material made from plants and animals. Biomass contains storedenergy from the sun. Plants absorb the suns energy in a process calledphotosynthesis. The chemical energy in plants gets passed on to animals and peoplethat eat them. Biomass is a renewable energy source because we can always growmore trees and crops, and waste will always exist. Some examples of biomass fuelsare wood, crops, manure, and some garbage. 16
  17. 17. Transforming Chemical EnergyThe matter contained in living organisms contains chemical energy. When organisms die, chemical compounds in their biomass break down. Bacteria, fungi, and other organisms help convert these chemical compounds to simpler chemicals that can be used by other living things. 17
  18. 18. Transforming Chemical EnergyThermal energy also is releasedas these changes occur. Example: A compose pile can contain plant matter, such as grass clippings and leaves. As the compost pile decomposes, chemical energy is converted into thermal energy. This can cause the temperature of a compost pile to reach 60° C. 18
  19. 19. Transforming Electrical Energy Every day you use electrical energy. When you flip a switch, or turn on a radio or television, or use a hair drier, you are transforming electrical energy to other forms of energy. 19
  20. 20. Transforming Thermal Energy Chemical energy changes into thermal energy when something burns. Electrical energy changes into thermal energy when a wire that is carrying an electric current gets hot. Thermal energy can be transformed into radiant energy such as when a bar of metal is heated to a high temperature, it glows and gives off light. 20
  21. 21. Generating Electrical EnergyEvery Power plant works on the same principle---energy is used toturn a large generator. A generator is a devise that transforms kineticenergy into electrical energy. In fossil fuel power plants, coal, oil, ornatural gas is burned to boil water. As the hot water boils, the steamrushes through a turbine, which contains a set of narrowly spaced fanblades. The steam pushes on the blades and turns the turbine, whichin turn rotates a shaft in the generator to produce the electrical energy. 21
  22. 22. Power PlantsAlmost 90 percent of the electrical energy generated in theU.S. is produced by nuclear and fossil fuel power plants.Other types of power plants include Hydroelectric and wind.Hydroelectric power plants transform the kinetic energy ofmoving water into electrical energy. Wind power plantstransform the kinetic energy of moving air into electricalenergy. Sources of Electrical Energy in the U.S. 20% Coal Oil 3% Gas 51% 9% Hydro Other Renewable 14% Nuclear 3% 22
  23. 23. Quick Review of Energy  Changing Forms Heat usually is one of the forms of energy produced in energy transformations. The law of conservation of energy states that energy cannot be created or destroyed; it can only change form. The total energy doesn’t change when an energy transformation occurs. As an object rises and falls, kinetic and potential energy are transformed into each other, but the total energy doesn’t change. 23
  24. 24. Generating Electrical Energy A generator converts kinetic energy into electrical energy. Burning fossil fuels produces thermal energy that is used to boil water and produce steam. In a power plant, steam is used to spin a turbine which then spins an electric generator. 24