Homeworks: Due 11:59pm on Thursdays (starting April 10) as pdf uploads to Canvas, the week after they are posted.
Final Exam: Due 2pm PDT Thursday June 5, 2025 for Seniors and Grad students. Due 2pm PDT Thursday June 12, 2025 for Frosh-Juniors.
Prof: Sterl Phinney [final]
316 Cahill
esp [AT] tapir.caltech.edu
Office hours: TBD
TAs: Annika Dugad [PS 1, 4, 5, 8, final]
[recitations 1, 5]
adugad [AT] caltech.edu
Office hours: W 5-6pm, B157 West Bridge
Yu Li [PS 2, 3, 6, 7, final]
[recitations 3, 7]
yuli2 [AT] caltech.edu
Office hours: W 5-6pm, B157 West Bridge
Kai L. Svenson [parts of PS 1, 3, 5, 7]
[recitations 2, 4, 6, 8]
ksvenson [AT] caltech.edu
Office hours: Weds 5-6pm, B157 West Bridge
Approximate class outline (may change depending on student and instructor enthusiasms...)
Week 1 Estimation, Dimensional analysis, scaling 2 More scaling, Bulk Properties of materials 3 Properties of materials 4 Water waves, Sound waves and acoustics, musical instruments 5 Weather, oceans and atmospheres, climate change. 6 Birds, airplanes, helicopters, spacecraft, lift, drag, boundary layers 7 Non-renewable and renewable energy: physics and transitions. 8-9 student vote from topics below Topics: -Biomechanics and exercise -OoM Economics, industry and finance. -Order of Magnitude math. -Earthquakes and their effects. -atomic and nuclear physics; energy levels cross-sections and reaction rates. -Meteors, meteorites, asteroids. -Covid-19 and other virus spreading -Astrophysical objects: stars, planets, cosmology, the anthropic principle. -Biology: neurons, information processing. Evolution, metabolism, lifetime. -Bombs, guns, torpedos, nuclear reactors, supernovae and other things that go bang. -Challenge me!
Final exams: see due dates above.
Solution sets will be posted on Canvas.
If your extension homework is more than one week late, or if more than one homework is late by x hours, 0.1*ceil(x/24)*(maximum possible score) will be subtracted from your score (i.e. you lose 10% of the maximum possible score per day or fraction thereof). Other extensions will only be granted for extraordinary reasons ---documented health issues, family emergency, etc. You must consult Sterl in person or by e-mail, before the homework is due. Some sort of proof of extenuating circumstances will be necessary. The one free extension in the previous bullet item is designed to satisfy other reasons such as ``I had too much other work'', or ``I was preparing for a conference'', so don't waste it and expect additional extensions for such reasons.
In the event that Senior Ditch Day falls on a Monday, Tuesday or Wednesday, the homework that would have been due that Thursday will instead become due on Friday of that week.
Your grade will be a mostly monotonic function of
g = [0.6(sum of homework scores)/(total possible)
+ 0.1(sum of class participation scores)/(total possible)
+ 0.3(score on final exam)/(total possible)].
Because new topics and new problems are given every year, and the
mix of students varies,
Sterl determines the connection between letter
grade and numerical score by looking at natural
breaks in the final distribution: there are no fixed cutoffs and no
predetermined curve.
However as a very rough guide, here are the grade cutoffs for previous years:
| Year | A+ | A | B | C |
|---|---|---|---|---|
| 2023 | 0.90 | 0.84 | 0.71 | 0.60 |
| 2021 | 0.90 | 0.83 | 0.70 | 0.60 |
| 2019 | 0.90 | 0.80 | 0.70 | 0.55 |
| 2017 | 0.93 | 0.89 | 0.75 | 0.65 |
| 2015 | 0.82 | 0.75 | 0.60 | 0.45 |
| 2009 | 0.90 | 0.80 | 0.67 | 0.50 |
| 2007 | 0.90 | 0.85 | 0.75 | 0.60 |
Collaboration and use of internet tools on the homework is limited. You must first try every homework problem BY YOURSELF for at least 30 minutes without external help (human or internet), other than looking up fundamental equations (e.g. Navier-Stokes, Schroedinger, Planck black-body, etc) in the recommended texts. This is the fun, OoM part. For estimation problems, this in particular means you must work out an answer using only what is in your brain before typing anything into a search engine. If subsequent Googling suggests your estimate was way off, you can then try to understand what went wrong with your estimate (or, not infrequently, with the dubious web "information"). If you do use Google or other internet search methods to look up or check numbers, you must report that you did so, and give the sources you used on your homework. However, it is strongly recommended that you do your best to avoid checking numbers in this way.
Use of generative AI/Large Language models (ChatGPT and its many relatives: `AI')) or online tutoring sources (OT) as an aid to solving the homework problems, and searching for homework problems, or their close relatives online is strictly forbidden, and will be considered a violation of the Caltech Honor Code. See the PMA policy on AI, IR, OT.
Visual exchanges of information are also strictly forbidden -you may not trade equations, graphs, or look at other people's solution sets from this or any prior year, or from child or grand-child Ph 101-like courses at other universities.
You may consult books, published papers, and internet sources to learn or remind yourself of relevant physics. The recommended texts are (surprise) recommended.
If after spending 30 minutes on a problem you are still stuck on it, you may TALK about the homework with the TA or your fellow students, but all exchanges of information must be general in nature and either exchanged verbally, or with modern replacements for talking (i.e. texting and emailing is ok too, as long as details are avoided -see below). For example the following QandA is ok Q: "I got a density of one atom per cubic km. Isn't that awfully low for lead at room temperature and pressure? A: "Yup, sure is. What variables did you include in your Buckingham Pi list? Oh, I think quantum mechanics is relevant here. Why did you leave out hbar? The following one is NOT OK: Q: "I'm stuck on problem 2. Can you help me?" A: "Sure. You take equation 3.12 of this book, insert equations 2.5 and 3.2, integrate and you should get the right answer which is V k squared over pi squared".
After any discussion with others, you must write up your own homework by yourself, without reference to anyone else's.
In real research, no one else knows the answer to the problems you work on (otherwise why would you be doing them?), so the most important thing you can learn from homework is how to think and solve for yourself, and be confident in your answers.