Re: The Rise and Fall of Simple Machines.

[brian whatcott <inet@INTELLISYS.NET>]

At 20:43 11/24/99 -0800, Leigh wrote:

> >                   dT = 2E11/(500 7800) (0.01)^2 = 5K
>
> ... This result is greater than I expected,
> but 1% is a huge strain. It corresponds to a tensile stress of two
> gigapascals (in pressure units), far beyond the tensile strength of
> steel (0.4 GPa in Hecht). 0.2 % strain seems to be about as far as
> you can go, which would bring the temperature rise down to 0.2
> degrees C. It is clear that a steel-spring windup car will never
> compete with battery electrics as a low emission vehicle.
>
> Leigh

This was part of the charm of the question for me.
A great virtue of steel is its extended ductility,
so that after the linear range, it keeps on truckin' to 10%
extension in some cases, meanwhile slip sliding in plastic strain.

 Your intuition is not to be disregarded: I think there may also be
a factor of two in the result - which is not material to the discussion.

I saw something unexpected the other day in a magazine called
"NASA Briefs". There was an advert for a clockwork one shot gyro for
 two axis inertial guidance for missiles and the like, which provided
 guidance for a minute or two - shades of "Clockwork Orange".
(Wasn't that a Feynman anecdote? - setting a high speed gyroscope
running in a victim's suitcase, then watching his difficulties as
 they turned corners?)



brian whatcott <inet@intellisys.net>
Altus OK