Energy 8th Grade
Energy REVIEW • What is energy? • Energy – the ability to do work • Potential – stored energy • Kinetic – energy of motion • Energy can change from one form to another.
Conversions of Energy p.130 • How can energy change? • Energy can change (convert) from one form to another • Sun to humans
Gas to car • Sun to gas • Coal to steam • Wind to toaster
Types of energy • ______________ • Energy that has the ability to do work • Example: Driveshaft on a car, Draw Bow String • ______________ • Energy stored in the bonds between atoms and molecules • Examples: Food, Gasoline • _______________ • Energy carried by moving electrons in an electrical conductor • Example: Electricity
Types of energy • _____________ • Energy from Electromagnetic Waves • Example: the Sun • ________________ • Energy related to temperature (due to moving atoms and molecules) • Example: Creation of Steam from water • _________________ • Energy released when atoms are split (fission) or added (fusion) • Example: Nuclear reactor (fission) Stars (fusion)
Types of energy • Mechanical • Energy that has the ability to do work • Example: Driveshaft on a car, Draw Bow String • Chemical • Energy stored in the bonds between atoms and molecules • Examples: Food, Gasoline • Electrical • Energy carried by moving electrons in an electrical conductor • Example: Electricity
Types of energy • Radiant Energy • Energy from Electromagnetic Waves • Example: the Sun • Thermal Energy • Energy related to temperature (due to moving atoms and molecules) • Example: Creation of Steam from water • Nuclear Energy • Energy released when atoms are split (fission) or added (fusion) • Example: Nuclear reactor (fission) Stars (fusion)
Discussions: • Describe one of your energy uses to a table partner. • Where does that energy start in the energy cycle • What might be the pathway for that energy to get to you.
Design a wind turbine • Criteria: • Work with your table • Use materials available • Make it spin • All parts must be taken apart before the end of class • Please do not break or damage the materials • Complete reflection
Reflection – pg 131 (below notes) • Write down what DID and DID NOT work when building your windmill. (we will reference this later) • How would you explain this to a 3rd grader?
Quick review: work and power • Force = mass x gravity • Work = Force x Distance • Power = Work time
Goal for today • Rebuild your windmill and lift as many washers as you can 0.5m • Calculate the Work and Power required to lift your maximum amount of washers
Page 131: Day 2 reflection • Work and power calculations. • What part of Design was the most difficult? • How might you go about your design differently the next time?
Pg 133-134 • Blade investigation
Energy Use Notes: Pg 135 • How much energy do you use? • Energy – the amount of work done by an appliance • Power – the RATE at which energy is used • Electrical power is measured in Watts
Energy use notes continues • 1 Watt = the power needed to raise 100g, 1meter in 1 second • 1 kilowatt (kW) = 1,000 watts • Phantom/ vampire load – energy that appliances use even when they are turned off
pg 135 (below notes) • Write 3 things you genuinely learned from the reading • When done, start to copy down the data table on page 136
Below data table • Answer questions 1-7 from the Kill-A-Watt lab sheet.
Conclusion questions - • What was the largest power user? • Were you surprised by any of the appliances? • Will this change at all how you might use electricity?
Ohm’s Law pg 137 • What is Ohm’s law and how do you use it? • Current • The FLOW of electrons in a wire • Measured in amperes (A) • Voltage • The PRESSURE available to move electrons • Measured in volts (V)
Ohm’s Law • Resistance • The opposition to the flow of electricity • Caused by friction • Measured in ohms ( Ω ) • Ohm’s Law • Voltage = (current) (resistance) • V= I x R • V = A xΩ
Ohms law practice • Complete the practice questions below the circuit picture on page 138. PLEASE do all questions. Thank you! • When done, explain the relationship between I, V, and R in this picture. (below your practice questions)
Fusion vs. Fission Fusion • Combining of smaller elements • Occurs in Nature • Produces many radioactive waves • Fuel is Hydrogen Fission • Breaking of larger elements • Does not occur naturally • Little radioactive waves produced • Fuel is Uranium
Fission notes pg 139 • How is energy produced through nuclear fission? • Splitting of an atom’s nucleus into two smaller nuclei • Uranium-235 hit with a neutron • U-235 splits into two smaller nuclei and two neutrons • Those neutrons hit more U-235 setting off a chain reaction • As nuclei split, energy is released as heat
Wrap-up: • Discuss with a partner then write in your notes: • What are two differences between fission and fusion? • Do the benefits of energy generation from nuclear fission outweigh the risks? Why or Why not? • If you were the POTUS what would your energy plan be concerning nuclear energy?
Solar Energy Notes pg. How does passive solar energy work? • The sun radiates infrared waves or thermal energy to Earth • This thermal energy heats Earth
Passive Solar Example Notes • When we use the sun to heat things directly, we are using passive solar power • This is a solar oven
Daytime Winter Passive Solar Power • Passive Solar Power can also heat homes
Active Solar Energy How does solar energy create electricity? • The sun also provides light energy in the form of visible light waves
Active solar energy • Solar cells on solar panels convert this light energy into electricity
Active solar energy • Sunlight hits silicon on the solar panels and makes electrons move • The moving electrons create electricity
Sight Selection • You have been commissioned to build a Solar Powered House in a specific area about 3 kilometers in square area • You can use either Active or Passive Solar Power or both • You must answer the following 3 questions about your placement: • Why did you choose that sight for your home and which direction does it face? • What type of Solar Power you are using? • What more information would be useful?
Wrap-up • Share your design with a person who is at a different table: • Answer the following: • Why did you pick your sight selection? • Did your partner convince you that there is a better sight?