In message . com,
Robert Laws writes

Autolycus wrote:
"T i m" wrote in message
...

So, failing a 'yes' to the above, is there a simple formula (rule of
thumb) for how much 'stiffer' any particular steel would be for a
percentage increase in diameter please?

Say I go from 3/8 to 1/2" for example, would it be 25% or 33% or
something else stiffer?

Stiffness is proportional to the fourth power of diameter for a round
beam in bending, so 3/8 to 1/2 inch is a factor of 4^4/3^4, or 256/81,
or 3 and a bit, as we engineers say (or pi, or root 10).


Did not the state of Kentucky once legislate that pi=3?.

I think we're venturing into the realm of urban myth here IIRC

--
geoff