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Unformatted text preview: Chapter 1 Numbers
The goal of this manual is to help you learn how to make diﬃcult scientiﬁc estimates of serious import. If successful, the student by the end of the course will be able to answer questions such as the questions listed below in a manner which relies signiﬁcantly less on other people and more on one’s own self. 1. Is it possible for human energy needs to be met by renewable energy sources? 2. If we do continue to use fossil fuels, how plausible would it be for us to scrub the earth’s atmosphere clean of all excess CO2 ? 3. How energy eﬃcient is a farm? 4. There is currently a debate in Washington as to whether we should stay in Afghanistan for another few years. Based on your own personal value system, how eﬃcient a use of resources is this? We will get to the goal of answering questions such as this one by breaking the process into several distinct steps. The ﬁrst step is in the treatment of numbers. 1.1
1.1.1 A ﬁrst look at numbers
Can we answer a how-many question even when we are not sure of an answer? Even when one doesn’t know the exact answer to a how-many question, one often has a sense of what the answer might roughly be. Try the question, How many miles is it from NYC to Chicago? One may not know the actual distance from Chicago to NYC. But one can still come up with a rough number. For a rough number one could proceed as follows. One starts by recognizing that 100 miles is too short a distance. (Lots of commuters in the US drive 100 miles a day. Nobody commutes by car from Chicago to NYC.) One could then 1 ...
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This note was uploaded on 03/01/2011 for the course CHEM 2090 taught by Professor Zax,d during the Winter '07 term at Cornell University (Engineering School).
- Winter '07