Energy in Thermal Processes

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Chapter 11 Energy in Thermal Processes
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• Temperature and heat
• Heat (Q) energy transferred between a system
  and its environment because of a temperature
  difference that exists between them
• SI Unit Joule
• Alternative unit calorie (cal)

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• Absorption of heat
• Specific heat (c) heat capacity per unit mass
• Common states (phases) of matter solid, liquid,
  gas
• Latenet heat (L) the amount of energy per unit
  mass transferred during a phase change (boiling,
  condensation, melting, freezing, etc.)

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Absorption of heat
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Absorption of heat
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Absorption of heat
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Chapter 11 Problem 17
A 100-g aluminum calorimeter contains 250 g of
water. The two substances are in thermal
equilibrium at 10C. Two metallic blocks are
placed in the water. One is a 50-g piece of
copper at 80C. The other sample has a mass of 70
g and is originally at a temperature of 100C.
The entire system stabilizes at a final
temperature of 20C. Determine the specific heat
of the unknown second sample.
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• Heat transfer mechanisms
• Thermal conduction
• Conduction rate
• Thermal resistance
• Conduction through a composite rod

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• Heat transfer mechanisms

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Chapter 11 Problem 36
A box with a total surface area of 1.20 m2 and a
wall thickness of 4.00 cm is made of an
insulating material. A 10.0-W electric heater
inside the box maintains the inside temperature
at 15.0C above the outside temperature. Find the
thermal conductivity k of the insulating
material.
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• Heat transfer mechanisms
• Thermal radiation
• Radiation rate
• Stefan-Boltzmann constant
• Absorption rate

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Chapter 11 Problem 46
At high noon, the Sun delivers 1.00 kW to each
square meter of a blacktop road. If the hot
asphalt loses energy only by radiation, what is
its equilibrium temperature?
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• Heat transfer mechanisms
• Convection

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Heat transfer mechanisms
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Questions?
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Answers to the even-numbered problems Chapter 11
Problem 4 0.152 mm
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Answers to the even-numbered problems Chapter 11
Problem 12 467 pellets
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Answers to the even-numbered problems Chapter 11
Problem 16 1.7 kg
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Answers to the even-numbered problems Chapter 11
Problem 20 49 kJ
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Answers to the even-numbered problems Chapter 11
Problem 40 7.2 10-2 W/(m C)
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Answers to the even-numbered problems Chapter 11
Problem 50 14.1 h