On 28/11/2008, Peter Bowyer <[EMAIL PROTECTED]> wrote:> 2008/11/28 Brian
Butterworth <[EMAIL PROTECTED]>:> > 2008/11/28 Peter Bowyer <[EMAIL
PROTECTED]>>> >> lb-force is (was) an imperial measure of force, so they're
perhaps> >> half-right.> >> > Newtons are> > m·kg·s-2> > Which is
distance x mass / time squared , lbs is just mass, unless "of> > force" is a
magical way of saying distance / time squared?>>> Yes, something like that.>>
I found a somewhat wordy discourse here:>
http://gwydir.demon.co.uk/jo/units/weight.htm>> (search for 'force')
... and Wikipedia is never wrong...
http://en.wikipedia.org/wiki/Pound-force
Force should always have dimensions MLT^-2, but you also need to knowthe
dimensions of the constituent units used in the F=ma calculation(there is
lb-mass and lb-force).
The original article athttp://news.rpi.edu/update.do?artcenterkey=2518 uses
Pounds of Force,and because this is an engineering rather than
gravitationalapplication (and is in the US), pounds-force is likely the
more'correct' unit to use. The Beeb could have used kiloponds as themetric
force unit, but that would require conversion...
Nick
-- Nick Morrott
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