Physics on the Back of the Envelope
Instructor
Roman Grigoriev
Office: Howey W304
Phone: 404-385-1130
E-mail: roman.grigoriev at physics.gatech.edu
Office hours: TBD
Place and Times
Textbook
None, but there are several good sources of relevant information:
In addition, you should print out a list of useful physical constants and values that come up often in order-of-magnitude calculation.
Course Description
The aim of this course is to help you transition from taking classes
to doing research by developing your problem-solving skills and
integrating the knowledge from your undergraduate (as well as
graduate) studies. We will focus on approximations (from very coarse
to very accurate) as a tool both to explore unfamiliar problems by
identifying the important physical phenomena and to check the results
of detailed (analytical or numerical) calculations. Order-of-magnitude
estimates, dimensional analysis, scaling arguments, and perturbation
theory will be used to analyze problems in classical and quantum
mechanics, thermodynamics and statistical physics, fluid dynamics,
biophysics, and astrophysics. However, the main emphasis will be on
methods rather than phenomenology.
Pre-requisites
You are expected to be familiar with classical and quantum mechanics and electricity and magnetism at the undergraduate level.
Grading
The class will be highly interactive, with all students expected to actively participate in the discussion. The grades will be based on class participation (10%) as well as homework (60%) and a final project (30%). You can discuss problems
with each other, but the solutions have to be executed and submitted individually. All students are expected to comply with
the academic honor code.
Grading scale:
A = 80-100%,
B = 70-80%,
C = 60-70%,
D = 50-60%,
F = 0-50%
Course Schedule
1. Counting and estimation
2. Scaling
The computed pressure inside both the earth and the moon exceeds the tensile strength of iron (3 MPa) and even high-strength steel (3 GPa). However, unlike the earth, the moon does not have much iron that can liquefy and generate magnetic field through the dynamo effect.
3. Dimensional analysis
4. Differential equations and scales
5. Perturbation theory
6. Matched asymptotic expansions
7. Multiple scale expansions
8. Atomic and molecular properties
9. Biomechanics
- Physical size:
- Skeletons of a
mouse and an
elephant. A paper with a more elaborate analysis of bone scaling.
- Paper on overall size of different types of animals.
- Distribution networks:
- Locomotion:
- Water striders walking (and resting) on water:
[movie],
[movie]
- "Jesus Christ" lizard running on water:
[movie],
[movie],
[movie]
10. Nuclear physics and astrophysics
11. Multi-physics problems
- Freezing boiling water: [movie]
- Shape and size of falling droplets and rising bubbles.
- Paper with detailed analysis of droplet breakup.
Homework Assignments