Quiz Review April 11, 2011 DRILL: Answer whether the heat transfer is conduction, convection, or radiation A thermos bottle has a shiny interior. What type of heat transfer does it prevent? Heat in the room moves with the warm currents from warmer areas to cooler areas. Brownies bake in a glass pan using these 2 methods. You feel the heat of a wood stove when you stand next to it. Radiation Convection Convection(from oven) and Conduction (through pan) Radiation and Convection

Quiz Review Solutions Movie on Wednesday/Thursday Quiz Tomorrow on Thermal Technology Take out review sheet Movie on Wednesday/Thursday -There will be an assignment, so you must pay attention Bookwork if disruption/throwing objects

Quiz Review Solutions 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.

Quiz Review Quiz Review Solutions List 3 example of Thermal Technologies and identify why they are considered a thermal technology. 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…

Quiz Review Quiz Review Solutions 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.

Quiz Review Solutions Natural Convection Forced Convection 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

Quiz Review Solutions Yellow Red White Blue Orange 3 1 5 4 2 Number the following from 1-5, 1 being coolest and 5 being hottest. Yellow Red White Blue Orange 3 1 5 4 2 Remember ROY G. BIV

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

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

Quiz Review Quiz Review Solutions 1. How much energy is required to raise the temperature of 10 grams of water by 40 degrees Celsius? Step1: Write down information Step 2: Write down equation E = ?? M = 10 gram C = 1 cal/(g*Celsius) DT= 40 degrees Celsius

Quiz Review Quiz Review Solutions 2. A microwave supplies 1,000 calories of energy to 50 grams of water. The heat capacity is 1 cal/(g Celsius). How much did the temperature increase? Step1: Write down information Step 2: Write down equation E = 1,000 calories M = 50 g C = 1 cal/(g*Celsius) DT= ??

Quiz Review Quiz Review Solutions 3. If the starting temperature for problem 2 was 20 Celsius, what was the ending temperature? Ending Temperature = Starting Temperature + Change Ending Temperature = 20 C+ 20 C Ending Temperature = 40 C

-In 10 min., be ready to hand it in. Quiz Review CLASSWORK -In 10 min., be ready to hand it in. With a partner next to you, identify 3 examples of Conduction, Convection, and Radiation (total 9 examples) not discussed in class. Explain how each energy is transferred in each example