Re: Loss of Mars Climate Orbiter due to units of measurment conflicts

[Ehud Lamm <mslamm@mscc.huji.ac.il>]

On Thu, 14 Oct 1999, Wes Groleau wrote:

|While I am personally in favor of the SI, I must insist that the
|"fundamental constants" are rendered in whatever units the renderer 
|chooses.  I was taught in high school that G = 32.2 ft / sec**2
|

Of course you can use whatever units you choose (well measuring distance
in kilograms is not really what I have in mind). But if you choose
constants based on units that don't agree with your measurements you might
crash a space vehicle....
I my last physics exam, which was a lab exam, I measured all distances in
cm. (we had to measure distance of movement after impact) - since all
movement was on a desk top. The constant was of course MKS, so my graph
looked kind of strange. I was flabbergasted for 55 minutes out of the
total 60, and only had time to add on the exam paper "the units!!! always
check the units!!! I used cm. and MKS"
Apperantly the tester liked it, since I got 90 something (I don't remember
exactly). It was really funny - beacuse I was the last guy out of there,
and beacuse all my claculations were wrong.
Well at least it didn't cost anyone $125 million... :-)

Ehud Lamm mslamm@mscc.huji.ac.il
http://purl.oclc.org/NET/ehudlamm <== My home on the web 
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