Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: a surprising escape speed problem



At 08:50 AM 10/26/02,John Mallinckrodt, you wrote:

[Brian Whatcott]

> 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

[Carl Mungan originally asked:]
Okay here's the question: With what speed (relative to the
earth) must you launch a stone so that it just escapes to infinity?

It seems then, that correct answer is that the usual Earth escape
velocity will be sufficient to allow the stone to proceed for ever, there
being no gravity well to climb due the Sun.
...Assuming no capture by other planetary bodies.


Brian Whatcott
Altus OK Eureka!

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