From: Lee Corbin (lcorbin@tsoft.com)
Date: Tue Oct 15 2002 - 09:58:38 MDT
Spike writes
> Yes, but think of it as the force needed to
> hoist 1/32 of a slug in a 1 G field.
>
> > I am stubborn, and I am old.
>
> You arent that old Lee.
But I am stubborn! And despite your exhortations,
I have finally succeeded in obtaining a slug-less
derivation.
> NO! Do not convert from a good system to
> a bad one. Think metric!
Oh YES! Always have. I hate ft-lbs and
all that. Especially, ugh, slugs. (Whatever
they are.)
> > and tell me how many foot-pounds (force
> > times distance) equal one joule (i.e. one
> > newton-meter)?
>
> Dont convert. Estimate the height in
> meters, the mass in Kg and work from there.
Listen, I can't help it if Mike Lorrey found
out the WTC data in practically the only way
he could, namely those awful English units.
[Four page rant about English vs. French
rivalry reluctantly deleted.]
> Lee, your sanity is not in danger bud.
> Think metric. spike
I'm trying! Okay, like I say, I finally did
it, and here is the slug-less derivation:
Voila:
1 ft-lb = 1.355818 newtons.
Proof: 1kg weight (not mass) is equal to
2.2046 pounds, as one knows from
daily life.
One also knows that 2.54 cm equals
1 inch. So there are .0254 meters
in one inch, and when we multiply
by 12 we get .3048 meters per foot.
Exactly.
One also has the acceleration of
gravity as 9.80665 meters/sec^2
Therefore, (warning!---view in fixed font!)
9.80665m 1kg .3048m
1ft-lb * -------- * ---------- * ------
sec^2 2.20452 lb ft
equals (i.e. multiplies out to be)
= 1.35588 m^2 * kg / sec^2
because all the units cancel out. But the
last expression is the definition of a newton.
So from now on I hope that it takes less than
hours to convert from ft-lbs (should the dreadful
need arise again) to newtons.
Lee
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