Re: Asteroid Problem

[Bernard Cleyet <anngeorg@PACBELL.NET>]

Right!

Thank you for suggesting further thought:    One needs to find a violation of the "Wiedemann-Franz ratio" for materials i.e. high tensile modulus, low shear.  Geometry will
help also.  The torque to produce twist angle g in a cylinder  is  pi*r^4*M*g/2l    (M is shear modulus, l length, and r the radius); while in a ribbon, a >>b,  r^4 is
replaced by a*b^3, where 2b is the thickness.  Therefore, one may support exceptionally great weight, yet with low torsional rigidity,  by making the suspension thin and
wide, (and long).  This explains why one description I read used 1/4 inch open reel mylar magnetic recording tape.  I've forgotten the reference (it's not Sci. Am.).  Could
it be PSSC?

Panzers, again!

bc


Clarence Bennett wrote:

> If you make the pendulum too heavy, you will need a stronger suspension, and that will change the restoring forces and may mask any improvement in measurement precision.
>
> At 1:58 PM -0400 8/31/01, Bernard Cleyet wrote:
> > This brings up a problem one of my students modeled for me on an analog
> > computer -- i.e. the non linearity expected from the motion of a
> > Cavendish pendulum very near one of the masses.  This is similar to the
> > gradient producing tidal effect.  In this case, anharmic motion
> > results.  A tedious calculation showed the effect is about one order too
> > small to detect with the Leybold apparatus (if I remember).  At some
> > point I hope to detect it by replacing one of the ~ 2 kg balls with a
> > tungsten (or DU --  there's plenty around in Kosovo, Iraq, AND Vieques)
> > cylinder and replacing the glass sides with saran wrap.   Perhaps
> > building a Cavendish with much massier pendulum balls may also help.
> > However, since, counter intuitively, their mass is irrelevant in the
> > measurement of G, this may also be so for this experiment.
> >
> > Any comments?
> >
> > bc
> >
> >
> >
> > Ludwik Kowalski wrote:
> >
> > > Our moon is about 30 earth-diameters away. In this case
> > > components of forces exerted on any little part of our planet
> > > are very small in comparison with perpendicular components
> > > (on my picture where the moon-earth line is horizontal).
> > > Thus lunar tidal forces (gradient of F) are essentially
> > > horizontal (on my picture). But this would not be so for
> > > an asteroid located only one earth-diameter away from
> > > the center of our planet. Would the vertical force
> > > components reduce the tidal effect? I would expect so.
> > >
> > > And I hope we will never have a chance to test this
> > > experimentally for a very massive asteroid. Can this be
> > > tested on a very small scale? For example, in solid tides
> > > mutually induced in two large cannon balls.
> > > Ludwik Kowalski
>
> Clarence Bennett
> Oakland University
> Rochester, Michigan
> 248 370 3418
> http://www.acs.oakland.edu/physics/staff_info/Bennett.htm