Gerhard Fiedler wrote:
> Which is of course a general advantage of doing calculations with the
> proper units throughout (including conversion factors). In many cases,
> you'll see immediately when something is wrong. I'm glad that I was
> introduced to physics in high school this way and have it done like this
> ever since.

Of course - this is the way I do it. However, you can make mistakes with 
units in much the same way you can mess up numbers when doing things on 
paper. For example, you could inadvertently flip a unit around when 
cancelling things out (essentially taking the reciprocal). Google is to 
calculations with units as a calculator is to calculations without 
units. Sometimes there just isn't enough time to do it carefully, too - 
with today's education, sometimes there is way too much 
formula-crunching. Google serves as a nice doublecheck on your formula 
units vs. operations, as well as calculating the answer at the same time.

As for conversion factors, I try to use SI throughout most things to 
avoid them - if you do the full copper thickness calculation by hand, 
you'll see most of the work is due to the use of funky imperial units.


-- 
Hector Martin (hector@marcansoft.com)
Public Key: http://www.marcansoft.com/marcan.asc

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