From: ram@zedat.fu-berlin.de
"J.B. Wood" writes:
>knowledge of physics) with a simple lowering of the exploration team
>down on a cable, and later winching them back up.
>Given this, you're correct: E_up must be larger than E_down due to the
>planet's gravitational field. The usual terms for this are "gravitational
The OP defined E-Down as "the amount of energy required by
the transporter".
When the team is lowered down a cable, the system cable+team
can /do work/ in the spaceship, for example, run a power
generator. So the energy /required/ to lower the team is
/negative/, E-Down < 0.
To raise the team up again, positive energie has to be
/supplied/ to the system cable+plus team, so E-Up > 0.
In mathematics, positive numbers are deemed to be larger
than negative numbers, so E-Up > E-Down (without the need
to ressort to more subtle physical phenomena).
PS: I will try to write my posts to this group in ASCII-only
from now on.
PPS: The OP wrote that the spaceship "assumes orbit around
an earth-sized" planet. A spaceship in orbit usually has a
huge velocity normal to the surface. When it lowers
anything on a cable, this shares that normal velocity.
However, when there is no atmosphere and the surface is a
perfectly spherical and the surface is made of a
hypothetical material with an extremely small friction,
it might be possible to survive this. But possibly the
large normal velocity would mean that the team will
immediately leave the surface again, or not even ever
arrive there. As soon as the angular velocity of the team
and the space ship differs, the cable will have to ...
Well one could go on and on about this, but maybe at this
point my time budget for this post is exhausted.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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