[SciPy-User] Error in constants documentation?

Arthur M. Greene amg@iri.columbia....
Tue Apr 6 15:08:53 CDT 2010


It would seem that there is some confusion, in the 
constants.html, between force and mass...

Strictly speaking, kg is a unit of mass, Newton a unit 
of force. Weight is force, not mass: A gold brick 
floating in interstellar space is weightless but still 
massive.  Pounds and kilograms can be equated, but only 
in some specified gravitational field (like at the 
surface of the earth, where we usually weigh things). 
So mass is the more fundamental quantity, since it does 
not depend on gravity for its value. In Imperial units 
(feet, pounds) the unit of mass is the slug: 
http://en.wikipedia.org/wiki/Slug_(mass). This is 
absent from the constants page.

Regards,

AMG

Warren Weckesser wrote:
> Florian Lindner wrote:
>> Hello,
>>
>> http://docs.scipy.org/doc/scipy-0.7.x/reference/constants.html chapter Force says:
>>
>> dyn 	one dyne in watts
>> lbf 	one pound force in watts
>> kgf 	one kilogram force in watts
>>
>> doesn't the watts actually have to newtons as the unit of force?
>>
>>   
> 
> There is a ticket with the same question here:
>     http://projects.scipy.org/scipy/ticket/1001
> 
> 
> Warren
> 
>> Regards,
>>
>> Florian
>> _______________________________________________
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>>   
> 
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