Energy

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  • Usually, some energy is "lost" or transferred into friction (heat and movement loss), so efficiency is never 100%. Still the overall amount of energy remains the same.
  • round gravity to 10 in most cases
  • round gravity (9.8m/s 2 ) to 10 in most cases
  • If the law of conservation of energy is true, where does the energy come from at the start of the uphill climb? (chemical/mechanical energy of the bicyclist) Where does the energy go at the end of the roller coaster? (heat of friction)
  • Discuss advantages/disadvantages of each
  • Discuss advantages/disadvantages of each
  • per capita = per person According to the CIA World Factbook estimate for 2010 the world consumes about 87 million barrels of oil each day.
  • Energy

    1. 1. Energy - The Fuel of Life
    2. 2. What is Energy? <ul><li>Energy is the ability to do work or cause change </li></ul><ul><ul><li>measured in units of Joules (J) </li></ul></ul><ul><li>Examples: </li></ul><ul><ul><li>sun melts ice cream </li></ul></ul><ul><ul><li>car engine burns gas </li></ul></ul><ul><ul><li>electricity powers a blender </li></ul></ul><ul><ul><li>batteries run a flashlight </li></ul></ul><ul><ul><li>food enables us to run </li></ul></ul><ul><ul><li>a carpenter swings a hammer </li></ul></ul><ul><ul><li>trains pull boxcars </li></ul></ul><ul><ul><li>a tornado rips off a roof </li></ul></ul><ul><ul><li>wood stoves warm houses </li></ul></ul>
    3. 3. Forms of Energy <ul><ul><li>Thermal Energy (heat) </li></ul></ul><ul><ul><ul><li>faster moving atoms collide more often and cause higher temperatures </li></ul></ul></ul><ul><ul><ul><li>i.e. water boils on the stove </li></ul></ul></ul><ul><ul><li>Chemical Energy (stored in atomic bonds) </li></ul></ul><ul><ul><ul><li>heat/light/sound is released during chemical reactions </li></ul></ul></ul><ul><ul><ul><li>i.e. your body gains energy after eating </li></ul></ul></ul><ul><ul><li>Electrical Energy (movement of electrons) </li></ul></ul><ul><ul><ul><li>the flow of electrons is converted into heat, light, sound or movement </li></ul></ul></ul><ul><ul><ul><li>i.e. hair dryer, radio, light bulb, MAX train </li></ul></ul></ul>
    4. 4. Forms of Energy <ul><ul><li>Radiant Energy (waves) </li></ul></ul><ul><ul><ul><li>electromagnetic waves carry energy that our bodies interpret as heat, light or sound </li></ul></ul></ul><ul><ul><ul><li>i.e. sunlight, radio transmissions, microwave ovens, x-ray machines </li></ul></ul></ul><ul><ul><li>Nuclear Energy (stored in atomic nuclei) </li></ul></ul><ul><ul><ul><li>nuclear fission & fusion occurs when protons & neutrons are split apart or forced together, releasing huge amounts of energy </li></ul></ul></ul><ul><ul><ul><li>i.e. nuclear reactors, the sun & stars, radioactive elements, geothermal heat </li></ul></ul></ul>
    5. 5. Law of Conservation of Energy <ul><li>Energy cannot be created or destroyed (1 st Law of Thermodynamics) </li></ul><ul><ul><li>it can only be converted from one form to another </li></ul></ul><ul><ul><li>the total energy in a system must remain constant </li></ul></ul>
    6. 6. Kinetic Energy <ul><li>Kinetic Energy = the energy of movement </li></ul><ul><ul><li>Depends on 2 things: </li></ul></ul><ul><ul><ul><li>an object's mass (m) </li></ul></ul></ul><ul><ul><ul><li>an object's velocity (v) </li></ul></ul></ul>KE = ½ m v 2 KE = 400 J 200 kg car travels 2 m/s KE = 40,000 J 200 kg car travels 20 m/s
    7. 7. KE = 40,000 J 200 kg car travels 20 m/s KE = 80,000 J 400 kg car travels 20 m/s Kinetic Energy = ½ m v 2
    8. 8. Potential Energy <ul><li>Potential Energy = stored energy due to movement against a force </li></ul><ul><ul><li>Depends on 3 things </li></ul></ul><ul><ul><ul><li>mass of the object (m) </li></ul></ul></ul><ul><ul><ul><li>magnitude of the force (i.e. acceleration due to gravity (g), which is 9.80665 m/s 2 on Earth) </li></ul></ul></ul><ul><ul><ul><li>the object's height (h) </li></ul></ul></ul>GPE = mgh
    9. 9. <ul><li>GPE = 100kg x 10m/s 2 x 50m </li></ul><ul><li>GPE = 10kg x 10m/s 2 x 50m </li></ul><ul><li>GPE = 100kg x 10m/s 2 x 50m </li></ul><ul><li>GPE = 100kg x 10m/s 2 x 1m </li></ul>Gravitational Potential Energy = mgh height = 50 m height = 1 m Big rock = 100 kg Little rock = 10 kg 50,000 J 5,000 J 50,000 J 1,000 J
    10. 11. Energy Conversions <ul><li>Energy is converted from KE to PE back to KE in this bicycle example </li></ul>
    11. 12. Energy Resources <ul><li>Renewable </li></ul><ul><li>Won't run out - can be replaced/replenished </li></ul><ul><ul><li>Solar & Geothermal </li></ul></ul><ul><ul><li>Wind & Hydroelectric </li></ul></ul><ul><ul><li>Biomass </li></ul></ul><ul><ul><li>Wave </li></ul></ul><ul><li>Non-Renewable </li></ul><ul><li>Limited supply - once it's used up, it's gone for good </li></ul><ul><ul><li>Fossil Fuels </li></ul></ul><ul><ul><ul><li>Petroleum </li></ul></ul></ul><ul><ul><ul><li>Natural Gas </li></ul></ul></ul><ul><ul><ul><li>Coal </li></ul></ul></ul><ul><ul><li>Nuclear </li></ul></ul>
    12. 13. Renewable Energy <ul><ul><li>Biomass </li></ul></ul><ul><ul><li>Solar </li></ul></ul><ul><ul><li>Geothermal </li></ul></ul><ul><ul><li>Wind </li></ul></ul><ul><ul><li>Hydroelectric </li></ul></ul><ul><ul><li>Wave </li></ul></ul>
    13. 14. Nonrenewable Energy <ul><ul><li>Coal Plant </li></ul></ul>Petroleum Wells <ul><ul><li>Natural Gas Pipeline </li></ul></ul>Nuclear Reactors <ul><ul><li>Fossil Fuels are formed by decomposition, heat & pressure acting on buried dead organisms over long periods of time </li></ul></ul><ul><ul><ul><li>Petroleum (crude oil) </li></ul></ul></ul><ul><ul><ul><li>Natural Gas, propane, kerosene </li></ul></ul></ul><ul><ul><ul><li>Coal, asphalt, tar </li></ul></ul></ul><ul><ul><ul><li>Paraffin wax, methane gas </li></ul></ul></ul><ul><ul><ul><li>Motor oil, grease, petroleum jelly </li></ul></ul></ul>
    14. 15. World Energy Consumption
    15. 16. Per Capita Oil Consumption

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