Energy

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GCSE Physics double award notes

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Energy

  1. 1. Energy GCSE Physics
  2. 2. Forms of energy <ul><li>3.5.1 describe energy transfers involving the following forms of energy; chemical, heat, electrical, sound, light, magnetic, nuclear, kinetic and potential (gravitational and strain). </li></ul>
  3. 3. Reference <ul><li>Physics CCEA pg 1 and 2 </li></ul>
  4. 4. 33 % Longer
  5. 6. Some Energy Facts… <ul><li>The U.S. has five percent of the world's population and uses 23 percent of the world's energy. </li></ul><ul><li>In one hour, your heart works hard enough to produce the equivalent energy to raise almost 1 ton of weight 1 yard off :the ground. </li></ul><ul><li>A decrease of only 1% in industrial energy use would save the equivalent of about 55 million barrels of oil per year, worth about $1 billion </li></ul>
  6. 7. Basically Energy… <ul><li>In order to do work we must have a source of energy. </li></ul><ul><li>When you eat a healthy nutri-grain bar you store up energy which can then be used by your muscles to physically do things. For a car to move it requires a force which is provided by mechanical work. </li></ul><ul><li>Whenever work is done energy is needed. </li></ul>
  7. 8. Top Ten Types of Energy <ul><li>Kinetic – energy an object has because it is moving. </li></ul><ul><li>Light – rays given off when an object glows. </li></ul><ul><li>Sound – vibrations caused when an object moves. </li></ul><ul><li>Electrical – produced when a current flows. </li></ul><ul><li>Nuclear – energy released when an atom splits. </li></ul><ul><li>Heat – moving molecules given out by fast vibrations. </li></ul><ul><li>Chemical – stored by food and fuels. </li></ul><ul><li>Elastic potential – energy stored in a stretched or squashed object. </li></ul><ul><li>Gravitational potential – energy an object has because of its position above the ground. </li></ul><ul><li>Magnetic - energy which exists between magnetic materials. </li></ul>
  8. 9. Energy Transfer <ul><li>Energy tends to change form- take for example the food we eat. The chemical energy is then changed into kinetic energy (as well as other types of energy) for our bodies to do useful work! </li></ul>
  9. 10. Energy Transfer Input energy Kinetic Output (useful) energy- electrical/light The Dynamo Output (wasted) energy- heat/sound
  10. 11. The Unit of Energy <ul><li>Energy is measured using the Joule or the kiloJoule (1000 Joules) </li></ul><ul><li>Check out what energy values can do what work… </li></ul>
  11. 13. Conservation of Energy <ul><li>3.1.11 understand that energy is conserved and describe energy changes in terms of the principle of conservation of energy. </li></ul>
  12. 14. Conservation of Energy <ul><li>Reference- Page 2 </li></ul><ul><li>Write out the law of conservation of energy </li></ul><ul><li>Another way of stating this law is that every time energy is transferred the input energy will be equal to the total output energy (sum of the useful energy and wasted energy) </li></ul>
  13. 15. Example <ul><li>Every second a car transfers 200 kJ energy in the petrol to 80 kJ of moving energy. Represent this transfer in a diagram. </li></ul>Input Energy = Output Energy 200kJ = 80kJ + 120kJ Input energy Chemical 200 kJ Output (useful) energy- Kinetic 80 kJ Output (wasted) energy- heat/sound 120 kJ
  14. 16. Try this question- <ul><li>A power station uses 1,000,000 kJ of chemical energy every second, but it only gives out 400,000 kJ of electrical energy each second. What has happened to the input energy? </li></ul><ul><li>Draw an energy transfer diagram to represent the transfer (include quantities and units). </li></ul>
  15. 17. Input energy Chemical 1 000 000 kJ Output (useful) energy- Electrical 400 000 kJ Output (wasted) energy- Heat/Sound 600 000 kJ Transforms to Kinetic The input energy has changed form to kinetic and then to both useful electrical energy and wasted energy. The input energy and output energy totals are equal as energy is conserved.
  16. 18. Energy Resources <ul><li>3.1.3 explain how energy resources such as wind and fossil fuels are ultimately dependent on the Sun’s energy. </li></ul>
  17. 19. Tracing Back… the source of all energy <ul><li>Listening to a song, electrical energy sent to your brain </li></ul>Nerve Cell Electrical Energy Loud Speaker Sound Energy Plug and wires Electrical Energy Power Station Kinetic Energy Fuel Chemical Energy Plants Chemical Energy
  18. 20. … the Primary Source The Sun Nuclear Energy
  19. 21. Energy Resources <ul><li>3.1.2 recall that there is a variety of energy resources , to include, oil, gas, coal, nuclear, biomass, wind, wave, solar, geothermal, tidal and hydroelectric and distinguish between renewable and non-renewable. </li></ul>
  20. 22. Types of Energy Resources <ul><li>http://www.educapoles.org/loader.swf?path=docs/projects/flash_animations/energy_7_different_kinds_of_energy_061205.swf&lg=en </li></ul>
  21. 23. Energy Resources <ul><li>3.1.4 describe the environmental implications of the use of energy resources, limited to generation of electricity by fossil fuels, nuclear fuels, hydroelectric power, wind farms, waves and tides. Appreciate the effect on the environment of the use of these energy resources, limited to the contribution of burning fossil fuels to greenhouse effect (brief outline only), land/sea use and nuclear waste . </li></ul><ul><li>3.1.5 evaluate the advantages and disadvantages of using various energy resources to generate electricity. This should take into consideration: reliability , how quickly the different types of power station can respond to changes in demand , the costs of building, operating and de-commissioning power stations and any additional information, including quantitative information, with which they are provided. </li></ul>
  22. 24. How is electricity generated? <ul><li>An electromagnet generator (a complex version of a dynamo) </li></ul><ul><li>A turbine </li></ul>
  23. 25. Energy transfer in a Power Station <ul><li>http://www.eon-uk.com/EnergyExperience/497.htm </li></ul>
  24. 26. Energy Resource Questions <ul><li>In class </li></ul><ul><li>Complete questions 5, 6, 8, 9, 14 and 15 on page 7 and 8 </li></ul><ul><li>For Homework </li></ul><ul><li>Complete questions 1- 3 on page 29 </li></ul>
  25. 27. Geothermal Energy The rocks not too far below the surface are quite hot, 500°C about 1 km down.
  26. 28. Geothermal <ul><li>In some areas there are 'hotspots' where the temperature below the surface is very high. This is usually near where the earth's tectonic plates meet. </li></ul>
  27. 29. Geothermal Energy <ul><li>Water can be heated by these hot rocks which lie beneath the Earth’s surface. </li></ul><ul><li>The steam from the hot water can be used to turn a turbine and generate electricity! </li></ul>
  28. 30. Geothermal Energy - Deep drilling is very difficult - Drilling can also be expensive Disadvantages - Renewable energy resource - Huge quantities of energy available Advantages
  29. 31. Biomass harvesting switchgrass
  30. 32. Biomass <ul><li>Biomass is a renewable energy source from wood, manure, garbage and agricultural waste. </li></ul><ul><li>When biomass is burned, energy is released as heat that can be transformed into electricity or fuel. </li></ul><ul><li>Manure can also be turned into electricity using the methane gas the solid manure gives off when put into a digester. </li></ul>http://www.energyquest.ca.gov/story/chapter10_flash/index.html
  31. 33. Biomass <ul><li>Collecting the waste in sufficient quantities can be difficult. </li></ul><ul><li>We burn the fuel, so it makes greenhouse gases. </li></ul><ul><li>Some waste materials are not available all year round. </li></ul>Disadvantages <ul><li>It makes sense to use waste materials where we can. </li></ul><ul><li>The fuel tends to be cheap. </li></ul><ul><li>Less demand on the Earth's resources. </li></ul>Advantages
  32. 34. Crossword Puzzle <ul><li>http://www.energyquest.ca.gov/games/crossword_puzzles/renewable_energy.html </li></ul>
  33. 35. Efficiency <ul><li>3.1.14 recall that efficiency is a measure of how much energy is transferred in an intended way and recall and use the relationships between efficiency, input energy and output energy. </li></ul>
  34. 36. Efficiency <ul><li>Reference Page 12 </li></ul><ul><li>- Read page 12 for extra notes on Efficiency </li></ul>
  35. 37. Efficiency is a measure of how good a device is at changing energy from one form to another. All devices waste energy, so the efficiency of a device is never 100%. There is a formula that allows you to calculate the efficiency of a device or of a process. Energy efficient light bulbs are more efficient than normal light bulbs because they w____ less energy, and more of the e______ energy that they are supplied with is converted into l___ energy and not h___. aste lectrical ight eat
  36. 38. The efficiency formula We can express efficiency mathematically using the equation: <ul><li>Efficiency = Useful energy out </li></ul><ul><ul><ul><ul><ul><li> Total energy in </li></ul></ul></ul></ul></ul>The efficiency formula is unusual because it has no units . It is a number between 0 and 1 or a percentage %. Useful energy measured in Joules (J) Total energy measured in Joules (J)
  37. 39. Efficiency for a bulb <ul><li>If you have a filament bulb and it is supplied with 100J of electrical energy which it converts to 45J of light energy. </li></ul><ul><li>How much energy is wasted? </li></ul><ul><li>In what form is the energy wasted? </li></ul><ul><li>What is the efficiency of the bulb? </li></ul>Efficiency = Useful Total = 45J/100J = 0.45 or 45% 55J heat

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