Re: potential energy

Adrian Hurt [email removed] writes:
>
> >		On the other hand, GmM/r is the escape energy of Sol,
> > which is the kinetic energy required to produce a velocity of ~30 km/s.
> > For a ship weighing say, 1 T, that's 4.5e11 J, or 450 000 MJ. Not to
> > be sneezed at.
>
> A ship accelerating at 1-G will achieve that velocity in less than an hour,
> using just its manoeuvre drive.  (To get to 30000 m/s using an acceleration
> of 9.8 m/s^2 will take 3061 seconds, i.e. 51 minutes.)  Maybe not to be
> sneezed at, but that's the sort of figure that all spacecraft play with
> routinely - that's why you don't want to collide with anything!

Perhaps that is one answer -- require all ships entering jumpspace to
have enough kinetic energy (speed) to escape from the local star's
gravity well.  Then, a ship jumping from Sol to empty space would end
up with (almost) no kinetic energy after the jump, then after jumping
to Alpha Centauri it would gain as much kinetic energy as potential
energy that it lost.

Of course, there will have to be extra energy expended for the jump
itself.  Probably that energy would be expended as lost heat energy
or something.

> So the ship expends its 4.5e11 J, and get into jump space.  One week later,
> it emerges from jump space near Alpha Centauri, and gets 4.5e11J back -
> what happens to this energy?  Presumably it gains this energy as it emerges
> from jump space, and the energy ends up back in the ship's jump capacitors.

As I mentioned, the energy could just as easily be transferred into
kinetic energy.  Or it could go into the jump capacitors.  As long
as you aren't getting free energy from the jump, I don't mind how
it is modelled.

Jerry Williams ([email removed])