Transcript 18.Thermal

Fall wk 2 – Thus.7.Oct.04
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Welcome, roll, questions
Thermal physics
break
continue Calculus Ch.1
Looking ahead
Energy Systems, EJZ
Discuss Ch.18, Thermal physics
• Key points?
• Insights from team discussion?
• Questions?
- questions of fact: Can we find answer
in the text? What page?
- Outstanding questions of fact
- Outstanding significant questions
Thermal Physics - outline
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Temperature
Heat = energy
Discuss examples
Absorption of heat by solids and liquids
Work done by a gas (more next week)
Practice: conceptests and HW
Temperature
TC = T – 273 °
TF = 9/5 TC + 32°
ConcepTest 16, 18, 19
Heat = energy
Energy = work = force * distance
Force = Mass * Acceleration
Acceleration = rate of change of speed
Speed = distance / time
units of Speed (m/s)
units of Acceleration (_____)
units of Mass (kg)
units of Force (______) = (Newton) = (N)
Units of Energy:
Heat = energy: units
Units of energy or work: Joules = Newton * meter
In fundamental SI units of space (m), time (s), and mass (kg):
SI energy units (J) =
CGS units: space (cm = 10-2 m), time (s), and mass (g = 10-3 kg):
CGS energy units (erg) =
What other units have you encountered for energy?
cal = 4.1868 J, kcal = _______, cal = 4 x 10-3 BTU
BTU = ________ Joules? ConcepTest 38
Absorption of heat by solids and liquids
Thermal equilibrium: if TB = TA and TC = TA then TC = TB
Heat Capacity: Q = C DT
Specific Heat: Q = c m DT
Heats of transformation: Q = L m
boiling or condensing: LV; Freezing or melting: LF
ConcepTests: TE 1,3; C 40-42 ; L 53, 54, 60
Problems
Work done by a gas (CT 3, 64, green)
Work done = pressure * volume = area under curve (clockwise)
Heat added = work done + change in internal energy of gas
Thermal Physics HW
Questions: #3 (Lf), 6 (cycle), 8 (radiation)
Candidate problems:
Ch.18.5: #4 (C,F), 5 (conversion)
Ch.18.8: #24 (diet), 26 (butter), 27 (watts), 28
(garage), 29 (water heater BTU), 32 (cooling), 33
(solar heater), 35 (cooling gas)
Additional: #73 (work), 80 (solar house), 85
(transformations), 94 (radiation)
We will choose (in class) half of these to be due
next week, and half for the following week.
Calculus - outline
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Q about today’s HW
Review 1.1-1.3
Practice with logarithmic functions
1.4 Trig review
• Wiley says they have fixed eGrade – please
see if your registration works
• If eGrade doesn’t work for you yet, hand in
paper homework for now.
Calc 1 HW 2
Homework due next Thus:
Ch.1.4 # 1, 14, 18, 26, 35
Ch.1.5 # 1, 14, 16, 20, 29, 31, 34, 36, 40
Ch.1.6 # 2, 4, 8, 14, 18, 23, 28
Recommendations:
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Work odd problems for practice first, since you have
their solutions
Work due problems on scratch paper first, then input
electronically for detailed feedback
Discuss:
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Shorten assignments, stretch syllabus?
Teamwork on homework
Qualitative reasoning center
Looking ahead
• Seminar in Sem II C2109 tonight
• Please put your team’s best Q on the board before
5:00
• Tomorrow:
– Post your research assignment individually
– One-page essay about your learning this week?
– TA Brian Orr available in QRC Friday 10am - noon
• Next week:
– TA available in homeroom Wed 1-3
– visitors will discuss sustainability and solar panels on
Tuesday and Wednesday
ConcepTests: Temperature & Heat
ConcepTests: Temperature & Heat
Thermal Equilibrium ConcepTests
Specific / heat / capacity ConcepTests
Heat of transformation ConcepTests
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Work done by gas ConcepTests
Preview of power
Power = rate of doing work = energy / time
SI units of Power: Watts = Joules/sec = ____
Horsepower = 1 hp = 550 ft * lb/s = 746 Watt
What is a kilowatt-hour?
A. Power
B. Energy
C. Other