Warm up: Write down 10 things you can do conserve energy Grab a Book!!!

Kinetic-Potential-Chemical Rock balance on the edge of a cliff A piece of coal A landslide Roller coaster car A diver on a 10 meter platform A car battery tides

Goals Describe heat transfer by conduction, convection, and radiation Describe conversion of mechanical energy into heat Describe the second law of thermodynamics and how it relates to electricity

Heat transfer : Activity A There are station2’s: hot water and cups. On your paper : Which will keep the water hot longer Metal or Styrofoam and why? Design an experiment to prove your hypothesis Carry out experiment after I see what you wrote down Write down your results There are station 1’s :100W light Bulb On your paper : Describe what happens to the temperature of your hand as you move it towards and away from the bulb. Describe the change in temp of your hand when you hold a piece of paper between your hand and the bulb Compare and explain the temp difference of your hand when u hold it above the light bulb verses near the light bulb

Station 3 is at your table Differences in temp inside over time and why? Design an experiment.

Time in minutes Uninsulated Solar cooker Temp in Celsius Insulated Solar cooker 66 30 76 88 60 82 94

Thursday December 10 Warm Up : What is heat? Grab a book! Energy transferred from a hotter system to a cooler system when they contact

Solar Cooker which one get hotter faster? Time in minutes Uninsulated Solar cooker Temp in Celsius Insulated Solar cooker 66 30 76 88 60 82 94

Part B Kinetic Energy, Potential, Energy and Heat What is Kinetic energy? Energy of motion What is potential energy? Energy of position How does the kinetic energy of the clay change over time? How does the potential energy of the clay change over time? How was the kinetic transformed to potential? How was the kinetic transformed to heat and how? Create you own example of the 3 changes and record

Energy Units Part C Force: 1 Newton= .225lbs=1 J(joule/meter) Work= Force X Distance Power Work/Time

Energy Units Part C 1. A Make a concept map of the table 2.a Do you think you can produce power equal to that of a 100-W bulb? Calculate the power of a steel ball that weighs 5lbs. 3. Work(joules)= force(Newtons)X distance(meters) Work to lift the 5lbs ball 2 meters 4. Power(watts)= work(J)/time(s) Power to by lifting the ball 10 times in one minute

2a:Force 5lb X(1N/0.225lb) = 22.22N 3a Work=FXD Work = 22.22N X 2X2meters =88.88J 4a : Power= W/t (10 X 88.88J)/60s= 14.8 Watts 100watts? 40 X 89J/120s =29.6 watts 40X (22.22N X12meters)/120s=88.8 Watts

2a: 5lb X(1N/0.225lb) =22.22 N Work=FXD 3a : 22.22N X 2m=44.44J Make a concept map of the table 2.a Do you think you can produce power equal to that of a 100-W bulb? Calculate the power of a steel ball that weighs 5lbs. 3. Work(joules)= force(Newtons)X distance(meters) Work to lift the 5lbs ball 2 meters 4. Power(watts)= work(J)/time(s) Power to by lifting the ball 10 times in one minute 2a: 5lb X(1N/0.225lb) =22.22 N Work=FXD 3a : 22.22N X 2m=44.44J Power= W/t 4a : (10 X 44.44J)/60s

Warm-up” What happens as you move your hand closer to a heat lamp Warm-up” What happens as you move your hand closer to a heat lamp?   What happens if you put a piece of paper in between your hand and the heat lamp?     I made a pot of steaming hot chocolate and poured it into a metal cup and a styrofoam cup, which cup will keep my hot chocolate hotter?

In the diagram below at what distance in meters is the highest potential energy?____________ Power____ (a) = mass X acceleration (in Newtons) Force____ (b)= force X distance (in Joules) Work____ (c) = W/t (in Watts)

Calculation Calculate the power when you lift a 5 lb Ball 10 times 5 meters in 100 seconds? (1N= .225 lbs) Force = 5 lb X 1N/.225 lbs =22.22 N Work = Force X Distance; 22.22N X 10(2X5meters)= 2222.22 Joules Power = Work/time; 2222.22 Joules/ 100s = 22.22 watts

Digging Deeper Heat Transfer Atoms and the speed of their electrons As you increase heat you increase the movement(vibrations) of electrons and visa versa when you decrease. But when atoms get to absolute zero @ -2730C that would be the only time they would stop moving In the hot water activity Monday which cup was the conductor and which was the thermal insulator? Conductor= metal cup, insulator = Styrofoam cup, Conduction is one form of heat transfer.

Digging Deeper Heat Transfer Another heat transfer is when hot air/water rises and cooler air/water falls that is called? Convection

Digging Deeper Heat Transfer Xrays, Sun, TV waves, etc is another form of heat radiation is called? Electromagnetic radiation 3 forms of heat transfer is ? 1 Conduction 2 Convection 3 Electromagnetic radiation

Energy 4 forms of energy? Kinetic energy: energy of motion, when the clay went up. Potential energy: energy of position, when the clay got to max height Chemical energy: breaking chemical bonds, burning wood Mechanical energy: energy of work, when the you throw the clay up Work

Friction Friction: rubbing of hands the clay hitting the table? How?

Work and Power Work? The force you put on a object and the distance that object goes Work = Force X Distance, Joules and BTU BTU: Raising the temperature of a pound of water one degree Fahrenheit Power? A Rate! Work done over time Power = Work/time; Watts Joules/s, Horsepower ft-lbs/s

Friction Friction: rubbing of hands the clay hitting the table? How?

Converting Heat into mechanical energy How we make electricity Coal, natural gas, petroleum Break the chemical bonds to create heat Use the heat to boil water in closed container to produce steam. Steam builds to produce pressure that exerts force on a turbine.

Converting Heat into mechanical energy Converting mechanical energy is not 100%, can you think of ways energy is lost. Think about the 2 cups of hot water Heat loss, friction. Car engine: friction, not all the fuel is burned. % Efficiency = Work in/Work out X 100 Electrical power plant turbines 30% efficient, Wind power turbines 30-40%, hydropower turbines 80%

Summary

Goals Describe heat transfer by conduction, convection, and radiation Describe conversion of mechanical energy into heat Describe the second law of thermodynamics and how it relates to electricity