CH301H - Principles of Chemistry I: Honors
Spring 2014, Unique 51880

Extra Credit Assignment 2


Fermi Problems:  Fermi problems are a fantastic way to develop basic problem solving skills, as well as dazzle your friends at cocktail parties.  To solve a Fermi problem, you don't look up your facts or the answer on the Google, you guestimate.  You solve the problem using logic, general knowledge of the world, reasonable approximation of unknowns, back-of-the envelope calculations, and dimensional analysis.  They are named after the physicist Enrico Fermi, who used to start his freshman physics class at the University of Chicago every year with the problem "how many piano tuners are in Chicago?"  This is something that no one really knows (except perhaps the head of the piano tuners local 101), but the point is that you can come to a reasonable estimate by guestimating how many pianos are in Chicago, and then assuming the law of supply-and-demand holds, how many tuners are necessary to service all of those pianos.  (The Wikipedia page on Fermi problems covers this and other cute examples if you are interested.)  The point is not to get exactly the correct answer, but to get a reasonable estimate (say within a factor of 2, 5, or 10), with essentially no work.

We have reached a point in this course where Fermi problems about energy can touch on almost every aspect of life, and become extremely important when making important decisions about where and how to access, store, and expend energy. 

Problem: How much solar energy reaches Earth in 1 year? 


Assignment:
Write out your answer to this question, clearly identifying all of your assumptions and how you are choosing to solve this problem.  Give as much information as you need for us to evaluate the reasonableness of your answer.

Your answer will be due at the beginning of class on Tuesday, 25th March, to receive credit.