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Energy

Energy. Please take out your notebook, formula sheet and calculator. Energy. Def: the ability to cause change. Kinetic Energy. Def: The energy of motion Equation to calculate Kinetic energy KE = ½ mv 2 The units for energy are Joules (J). KE Videos.

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Energy

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  1. Energy • Please take out your notebook, formula sheet and calculator.

  2. Energy Def: the ability to cause change

  3. Kinetic Energy • Def: The energy of motion • Equation to calculate Kinetic energy • KE = ½ mv2 • The units for energy are Joules (J).

  4. KE Videos KE http://glencoe.mcgraw-hill.com/sites/dl/free/0078600510/161752/00035806.html

  5. Relationships • The more speed an object has, the more KE it will also have • ↑ speed ↑ KE VS 20 m/s 10 m/s

  6. The more mass an object has, the more KE it will also have • ↑ mass ↑ KE VS 1000 kg 100 kg

  7. Math Practice • What is the KE of a baseball moving at a speed of 40m/s if the baseball has a mass of .15kg? • KE = ½ mv2 • KE = ½ (.15kg)(402 m/s) • KE = 120 J

  8. What is the KE of a 1000 kg car moving at a speed of 10 m/s? • KE = ½ mv2 • KE = ½ (1000kg)(10m/s)2 • KE = 50,000 J

  9. PE  http://glencoe.mcgraw-hill.com/sites/dl/free/0078600510/160350/00035807.html

  10. Potential Energy • Def: stored energy. • Chemical potential energy – gas, food • Elastic potential energy – compressed spring, stretched rubber band • Gravitational potential energy – anything that can fall

  11. GPE • GPE can be calculated. • Mass x gravity x height • GPE = mgh • Lets practice some math! • Get out your calculators!

  12. Relationships • The higher an object is, the more GPE it will also have • ↑ height ↑ GPE

  13. Relationships • The more weight an object has, the more GPE it will also have • ↑ weight ↑ GPE

  14. More Practice • Find the GPE of a coffee mug with a mass of .3kg on a 1m high counter top. • GPE = mgh • GPE = (.3kg)(9.8m/s/s)(1m) • GPE = 2.94 J

  15. More Practice • Find the GPE of a 8000 N roller coaster car 45 m off the ground. • GPE = mgh = wt*h • GPE = (8000N)(45m) • GPE = 360,000 J

  16. Video

  17. Conservation of Energy • Energy can be neither created nor destroyed. • It CAN be changed, or converted. • KE to GPE and back is only one example!

  18. Forms of Energy • Chemical – charcoal, gas, batteries • Electromagnetic – electricity, magnetism • Light – x-rays, gamma rays, visible light • Mechanical – moving objects, KE+GPE • Nuclear – fission and fusion • Thermal or Heat – internal motion of molecules

  19. Examples • Rub your hands together. What does this do? • Is there a conversion taking place here? What is it? • Mechanical  Thermal

  20. More Conversions • What conversions happen in a car engine? • Chemical  mechanical  electromagnetic • Chemical  thermal • What about a light bulb? • Electromagnetic  electromagnetic and thermal • Electricity  Light

  21. What conversions happen when you eat?

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