get with a partner and go over your solutions to the 3g and 3f test review. pay particular attention...
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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 SolutionsTRANSCRIPT
• Get with a partner and go over your solutions to the 3G and 3F Test Review. Pay particular attention to #9 on the Fluid Technology side.
• You have ~12 minutes.
April 24, 2008
DRILL
Test Review
TEST FRIDAY – Unit 3F and Unit 3G(Fluid and Thermal Technology)
Test Review
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
2. List 3 example of Thermal Technologies and identify why they are considered a thermal technology.
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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…
2. 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.
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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
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5. Number the following from 1-5, 1 being coolest and 5 being hottest.
YellowRedWhiteBlueOrange
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1
2
3
54
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
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HigherLower
Temperature Difference (Difference of Temperature) Lacks
Convection, Conduction, RadiationRadiation
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:
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Convection
Conduction
Heat Pads
Car Engine / Basketball
Electric Stove
Incandescent Light Bulb
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1. What must be constant for Boyle’s Law to be usable? _______________________
2. Using gas to apply force or to transport is a particular type of fluid technology called _____________________.
3. Using a liquid to apply force or to transport is a particular type of fluid technology called _________________.
4. Why is aerodynamics considered fluid technology?
5. What are two things that fluid systems have in common?
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Temperature
Pneumatics
Hydraulics
1) Fluids 2) A pressure difference
Aerodynamics deals with the motion of air and other gaseous fluids and with the forces those fluids have on objects.
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6. Show mathematically why you would rather someone push against you with 10 lbs. of force on a 50 square inches piece of wood than with a 0.0031 square inch pinhead. (Hint: calculate the pressure of each)
1) Write given information:F = 10 lbsA1 = 50 in2
A2 = 0.0031 in2
P1 = ?P2 = ?
2) Write formula and solve:P1 = F1 / A1 P2 = F2 / A2
= (10 lbs) / (50 in2 ) = (10 lbs) / (0.0031 in2 )P1 = 0.2 psi P1 = 3225.8 psi
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I would rather someone use a block of wood since the pressure is MUCH less.
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7. Based on what we covered in the Fluid Technology unit, there are at least two ways to correctly label the axes of each of the graphs below. Do so.
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(Inversely Proportional)
0
10
20
30
40
50
60
0 5 10 15 20 25 30 35 0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0 5 10 15 20 25 30 35
(Proportional)
PorV
V or P
PorV
1/V or 1/P
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8. There are two ways to mathematically express the relationship between volume and pressure. Do so and explain. (Hint: Pressure and volume are inversely proportional.)
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a
a
[Volume is proportional to
1/P][Pressure is
proportional to 1/V]
V 1 / P or
P 1 / V
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9. On a separate sheet of paper write three new, different problems related to fluid technology. Use your previous problem sheet for examples. One problem should require use of the basic P = F / A formula. One problem should be a simple Boyle’s Law problem. One problem should use the diagram below. After writing these three problems, solve them.
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1. With a partner, identify 3 examples of Conduction, Convection, and Radiation (total 9 examples) not discussed in class.
2. Describe your observations of the heat transfer in each example.
3. Describe what is causing the heat transfer in each example.
Test Review