8.298 Selected Topics in Physics

Lies and Damn Lies: The Art of Approximation in Science

Homepage for an IAP physics course at MIT (2006). Course description:

How far can birds (and 747s) fly without eating? Why are raindrops a few millimeters in radius? How high can animals jump? How tall can mountains grow? How cold is the air at the top of Mt Everest? How hot is the interior of the sun? How much energy do gravitational waves carry? How fast do tsunamis travel? Even when these questions have exact answers, they are buried in the solution of complicated, often nonlinear differential equations. But by skillful lying -- the art of approximation -- you can understand these and other phenomena, and can enjoy the physics, chemistry, biology, and engineering of the world around you.


These problems (in PDF) cover Chapters 1 through 6. They are optional and are for you to check your understanding. I won't collect them, and they don't count for a grade.

Here are some solutions to the problems above.



These will come from a textbook on approximation that I am writing. For each chapter, turn in a reading memo at the beginning of class on the day listed. We'll discuss any questions and go through more examples.

Listeners/auditors are strongly urged to read the chapters and even do reading memos. First, there's lots more in each chapter (examples, discussion) than we can possibly do in a lecture, so if you don't read the chapters you'll be lost -- which is not good for you or for the class. Second, by doing a reading memo you'll read attentively and learn more.

Why am I so keen that you read the material before class? The short answer is that it's a much better use of class time for us to discuss physics rather than for me to read you a book aloud. Here is a longer answer (1.6MB PDF article), a classic talk by Robert Morrison on 'The lecture system in teaching science.'

Reading / Class topicTurn in memo / Discuss PagesSizeUpdated
Ch 1: Wetting your feet11 January (Wed)16159 KB2006-01-09 11:23:15 -0500
Ch 2: Scaling11 January (Wed)10132 KB2006-01-09 11:23:19 -0500
Ch 3: Dimensional analysis13 January (Fri)16175 KB2006-01-11 13:49:49 -0500
Ch 4: Fluid drag18 January (Wed)22237 KB2006-01-15 12:36:45 -0500
Ch 5: Mechanical properties20 January (Fri)20251 KB2006-01-19 01:01:51 -0500
Ch 6: Thermal properties23 January (Mon)22249 KB2006-01-22 12:49:46 -0500
Ch 8: Waves25 January (Wed)30318 KB2006-01-24 13:12:00 -0500
Ch 14: Weather pt. 11 February (Wed)8116 KB2006-01-31 20:42:09 -0500

More reading

Useful data.

Several books overlap with the themes of this course. My favorites:

More problems

There are problems to try at the end of each chapter, of varying difficulty. Try those that interest you, and ask any questions about them either in class or in section (Wednesdays 3pm), send me an email, or just stay after lecture to chat. These problems are for self-assessment -- for you to check your understanding -- not for a grade.