[ausev] A Joule is a watt-second

[Brian Lasseter]

On Mon, Jan 5, 2009 at 12:19 PM, Gil Dawson <Gil at gil.dawson.name> wrote:
>  From http://www.batesville.k12.in.us/Physics/ANet/Science/Measure/
> UnitsDictF2J.html
>
>> JOULE (J)
>>     The SI unit of energy. One joule is the work done by 1 newton
>> acting through a distance of 1 meter. One joule equals (1) 1 watt-
>> second;...
>
> A rather odd coincidence, wouldn't you think?  They must've fudged
> the whole SI system to make this work out.

There is nothing coincidental or fudged in the SI system.  SI derived
units are all defined in terms of SI base units and/or other SI
derived units.  The watt happens to be defined in terms of joules (not
volts or amps).

- meter, kilogram, and second are SI base units.
- The newton is the SI derived unit of force, equal to the amount of
force required to give a mass of 1 kilogram an acceleration of 1 meter
per second squared.
- The joule is the derived unit of energy, equal to a force of 1
newton traveling through a distance of 1 meter.
- The watt is the SI derived unit of power, equal to 1 joule of energy
per second.


http://en.wikipedia.org/wiki/SI_base_unit
http://en.wikipedia.org/wiki/SI_derived_unit


-- 
TTFN,
Brian "Lasso" Lasseter

"No Sane man will dance."   -Cicero (106-43 B.C.)