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Unit Review

Unit Review. Boyce. Questions 1-2. 6 forms of energy Potential energy (PE) Kinetic energy (KE) Chemical Potential Energy (CPE) Mechanical Energy (ME) Electrical Energy (EE) Radiant Energy (RE) Thermal Energy (TE). 5 Sources… I say 3! Sun (Fusion) Core (Fission) Moon (Gravity).

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Unit Review

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  1. Unit Review Boyce

  2. Questions 1-2 • 6 forms of energy • Potential energy (PE) • Kinetic energy (KE) • Chemical Potential Energy (CPE) • Mechanical Energy (ME) • Electrical Energy (EE) • Radiant Energy (RE) • Thermal Energy (TE) • 5 Sources… I say 3! • Sun (Fusion) • Core (Fission) • Moon (Gravity)

  3. Questions 3-4 • All life on Earth needs the Sun • Photosynthesis • Food • Light • Heat • We create “things” like light bulbs and motors to convert energy from a form we can not use into a form that we can: • A light bulb converts EE into light and heat! • A hydroelectric dam converts KE into EE!

  4. Questions 5, 6,7,8 = SKIP, 9, 10 Question #5 • The Law of conservation of Mass • Mass can not be created or destroyed, it can only be changed into different forms • The First Law of Thermodynamics • Energy can not be created or destroyed; energy is transferred between source and its surroundings; energy is accounted for through heat and work! Question 9 • Plants use energy from the sun (light) to make food! This is done through PHOTOSYNTHESIS! Question 10 • In regards to energy, the Earth is an open system, it constantly receives and releases energy. In regards to resources, the earth is a closed system…the amounts of minerals that are on Earth do not increase or decrease, they just move around

  5. Question 11, 12, 13 Question 11,12 • A calorie is the amount of ENERGY required to change the TEMPERATURE of 1 gram of WATER by 1 degree CELSIUS. • A CALORIMETER is used to collect and measure HEAT ENERGY. Question 13 • Heat (calories) = Mass of Water (g) x Temperature Change of Water (oC) x 1 cal/goC • HEAT = 15g x 76˚ x 1 cal/goC • HEAT = 1,140 cal

  6. Question 14, 15 Question 14 • Energy Content (cal/g)= Heat Given off (cal)/Mass of fuel burned (g) • 8,000 cal/2.1 g = 3809.5cal/g Question 15 • This is tricky… • 1.8g of candle wax burns and raises the temperature of 100g of water by 18˚C; what is the heat (cal) per gram of candle wax? Heat=100g x 18 ˚=1800cal Heat/Gram of mass burned =1800cal/1.8g=100cal/g

  7. Questions 16, 17 • What does efficiency describe? • Efficiency describes how well a system changes energy from one form to another. We use systems (machines) to change energy from a form that is not useful to a form that is useful. • Are any energy transitions 100% efficient? • NO! In fact, as the complexity of a system increases, the efficiency of that system decreases.

  8. Efficiency Problems Efficiency = (Energy Out/Energy In) x 100 Eff.=(986/3578) x 100 Eff.=27.6%

  9. History of Fuel… • In the early 1800’s = WOOD • In the late 1800’s = COAL • In the early 1900’s = OIL • Today = OIL • Tomorrow = wind?, solar?, nuclear? hydro?

  10. Energy Use/Value • We use different resources based on… • Availability • Price • Fuel Content • Technology • We measure the value of fuel… • Energy content • Calorie/gram

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