Re: a surprising escape speed problem

[Bernard Cleyet <anngeorg@PACBELL.NET>]

"On the other hand I think it *is* true that replacing the Sun with a string does not
appreciably change the required launch speed for escape from the Earth."

I thought the point was:  Is there a difference, appreciable or not?  (Too lazy to
reread the orig. post carefully.)

With the string the only forces are the rotating frame force and g due to the earth.
The point was the string didn't "act" on the stone?

With the Sun, the g of the sun replaces the string AND also acts on the stone.  The
result may not be appreciable, but is different, and, as already posted, the escape
speed depends on the direction of launch.

Am I missing something here?

bc who wonders what "appreciable" is.

John Mallinckrodt wrote:

> At 8:39 AM -0500 10/26/02, Brian Whatcott wrote:
>
> > I am probably missing the whole point of this puzzle which I thought was to
> > posit the replacement of the Sun's gravitational attraction with a string.
> >
> > I visualize a string distributed to act on every Earth particle, and
> > realise that
> >   this is a gravity force by another name. So the question turns out to be:
> > what is the effect on space launches if Earth's diurnal rotation is stopped?
> >   I take it that one loses the advantage of equatorial launches.
> >   And that's about it.
> >
> > Isn't it?
>
> No, it isn't at least for the following reason:  With the Sun in the
> picture, a launch speed that allows the object to escape from the
> Earth is far too small to allow it to "escape to infinity."  On the
> other hand I think it *is* true that replacing the Sun with a string
> does not appreciably change the required launch speed for escape from
> the Earth.
>
> --
> John Mallinckrodt        mailto:ajm@csupomona.edu
> Cal Poly Pomona          http://www.csupomona.edu/~ajm
>
> This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.