> Agreed. Many an exam question was corrected by me during an exam by
> checking the units and finding something amis. VERY useful sanity check.

As long as one has the courage of one's units.
eg
The unit of effectiveness of a rocket fuel is (arguably) seconds.
(thrust.seconds per mass of fuel).
The unit of fuel consumption of a vehicle is area (ie length^2 =3D
m^2)(more usually expressed here as l/100km)
or of fuel economy is inverse area =3D 1 / length^2 or m-2 (usually
expressed as eg mgg).

Force can look like eg kg.m-3.m^2.(m/s)^3 until you cancel wildly to
get kg. m^2. s-3.
It;s only when you decide that f=3Dma so kg =3D g.Newton =3D m.s-2.N that y=
ou f=3Dget
kg.m^2.s-3 .N.m.s^-2 =3D agh ... E&O ...where's the back of an envelope ...


         Russell
--=20
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