1. U3g – L3 Answer the following in your notebook: 1.What is a more scientifically correct way of saying “the ice cubes made my water cold”? 2.Identify the methods of heat transfer expressed in the pictures/diagrams below: April 8, 2011 DRILL Convection RadiationConduction The water transfers it’s energy to the ice. The water loses heat and the ice gains heat.

2. Test Review Heat Transfer Energy needed to change the temperature of a material depends on –The mass of the material –The type of material Conductors take less energy to heat than insulators –How much we increase the temperature

3. E = M * C *  T –E – Energy – measured in calories –M – is the mass of the substance measured in grams –C – is the heat capacity measured in calories/gram(Celsius)  T is change in temperature –Water has a heat capacity of 1 calorie/(g*C) Test Review Heat Transfer

4. Test Review Food 1 food calorie = 1,000 calories 1 pound of fat = 3,500 food calories

5. Test Review Heat Transfer How much energy is required to raise the temperature of 10 gram of water 20 o C. Step 1: Write down information E=?? M = 10 g C = 1 cal/(g *Celsius)  T = 20 C Step 2: Write equation E = M *C *  T Step 3: Substitute and Solve E = 10g*1cal/(g*Celsius)*20 Celsius E = 200 calories

6. U3g – L3 Is it Conduction, Convection, or Radiation? 1.Warm water rises in a lake. Cold water descends. 2.The sun transfers its heat to our planet through space. 3.A thermometer under your tongue shows that you have a high fever. 4.On cloudless nights, heat escapes from our planet and goes into space. Convection Radiation Conduction Radiation

7. U3g – L3 5.You place a spoon into a cup of cocoa and it gets hot over time. 6.A thermos bottle has a shiny interior. What type of heat transfer does it prevent? 7.Heat in the room moves with the warm currents from warmer areas to cooler areas. 8.Brownies bake in a glass pan using these 2 methods. 9.You feel the heat of a wood stove when you stand next to it. Conduction Radiation Convection Convection(from oven) and Conduction (through pan) Radiation and Convection

8. 1.Work with one partner and complete the Thermal Technology Test Review sheet. 2.What you don’t finish in class, you must finish for homework. 3.Quiz will be next Tuesday U3g – L3

9. 3. What is the purpose of using infrared photography if hot objects are often red to our eyes? The more powerful radiation heat is in the form of infrared light, which we cannot see with our natural eyes. Therefore, infrared photography allows us to “see” the heat given off by objects even if the material is not hot enough for there to be a color change. Test Review Test Review Solutions

10. 1.Define the following –Thermal Technology – the technology of producing, storing, controlling, transmitting and getting work from heat energy. –Thermodynamics - the science dealing with internal energy, heat, and work –Photon – a particle of light –Conduction – the transfer of heat through a substance by collision of molecules. –Convection – is the transfer of heat by movement of a fluid. –Radiation – the transfer of energy by electromagnetic waves. Test Review Test Review Solutions

11. 2.List 3 example of Thermal Technologies and identify why they are considered a thermal technology. Test Review Test Review Solutions Example applications: Furnace, Hot water heater, Toaster, Insulation, Heat exchanger, Refrigerator, Hot air balloon, Fan, Engine cooling system, Oven, Blow-dryer, Thermos, Heat shrink, Styrofoam, Radiator, Blanket, Winter jacket, Wool socks…

12. 4.What are the two types of convection? Explain each. Natural Convection –Fluid surrounding a heat source receives heat and rises (due to lower density) –Surrounding cooler fluid moves in to replace it. –Cooler fluid is heated, rises, and cycle continues. Forced Convection –Fans or other means are used to propel a fluid. –An convection current is induced. –Car engine and A/C are examples Test Review Test Review Solutions

13. 5.Number the following from 1-5, 1 being coolest and 5 being hottest. Yellow Red White Blue Orange Test Review Test Review Solutions 1 2 3 5 4

14. 6.(Solid / Liquid / No Medium) is the medium for conduction. 7.(Solid / Liquid / No Medium) is the medium for convection. 8.(Solid / Liquid / No Medium) is the medium for radiation. 9.Thermal energy always travels from a region of __________________ temperature to a region of __________________ temperature. 10.The driving force for heat transfer is ______________________________________________ 11.The more accurate way of saying an object is “cold” is saying that it ____________ heat. 12.The three methods of heat transfer are ____________________________________________. 13.The sun’s heat reaching us through space is an example of the method of _____________________. Test Review Test Review Solutions Higher Lower Temperature Difference (Difference of Temperature) Lacks Convection, Conduction, Radiation Radiation

15. 14.A car engine cooling system is an example of the method of _____________________. 15.Heat from a house in winter travels through the walls by the method of _____________________. 16.Give an example of a technology that combines chemicals to produce heat: ___________________. 17.Give an example of a technology that converts mechanical energy to heat: ___________________. 18.Give an example of a technology that converts electrical energy to heat: ___________________. 19.Give an example of a technology that converts light energy to heat: ___________________. 20.Sketch an example of Conduction, Convection, and Radiation: Test Review Test Review Solutions Convection Conduction Heat Pads Car Engine / Basketball Electric Stove Incandescent Light Bulb