Day 16 in SCI110: Heat and Specific Heat
- Spring 2005 Schedule
- Last time: Quiz 2, and Group Reports
- Reviewed results of motion lab
- Quiz 2 -- physics of motion
- Group projects
- Today: Specific Heat
- Return group projects -- nice job!
- 20 points -- presentation
- 30 points -- paper
- Return (and discuss) Quiz 2
- Mean: 16 (out of 25)
- SD: 4.3
- Trouble with the vectors....
- Still a few misconceptions
- Need to review Newton's laws
- Discuss heat, and specific heat
- Note: abbreviated reading assignment (in general -- I
suggest you do all the reading -- pages 64-81 -- at
some point)
- Note: this is the last topic covered on exam 2
- Chapter 4, p. 70-77, 80.
- What is heat?
- Measuring heat:
- calorie: the amt of energy (or heat) needed to raise the temperature of 1 gram of water 1 degree Celsius.
- British Thermal Unit: the amt of energy (or heat) needed to raise the temperature of 1 pound of water 1 degree Fahrenheit.
- 1 calorie = 4.184 J (Joules - measure of
mechanical energy)
- To heat up an object using heat Q:
- Q is directly proportional to the change in temperature
- Q is directly proportional to the mass of the object
- The constant of proportionality is the
specific heat of the material (see table 4.2, p. 73)
- Heat transfer:
- Conduction: transfer of energy from
molecule to molecule
- Convection: transfer of heat by a
displacement of groups of molecules with higher
kinetic energy
- Radiation: "all objects with
temperatures above absolute zero give
off radiant energy" -- this is energy
in the form of light (or other rays
invisible to the human eye --
e.g. infrared)
- Phase changes and heat energy
- Goal: understand figure 4.18, p. 77
- Laws of thermodynamics
- First Law: energy cannot be created or
destroyed: merely changed from one form
into another.
- Second Law: natural processes proceed
toward a state of increasing disorder
- Specific Heat Experiment (pp. 62-63)
- Explore topics in Science News for Final Projects (proposals due Mar 17, Presentations Apr 28)
- Homework:
- Prepare problems 1-12, p. 83
- Come up with your final presentation topic!
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